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Aim The aim is to evaluate which of the existing scoring systems of histological response to neoadjuvant chemotherapy best stratifies the clinical outcome of patients with localized Ewing sarcoma of bone. Methods 474 patients with diagnosis of localized Ewing sarcoma of bone were included. The median follow-up was 13.5 years. Results The overall survival and the disease-free survival (DFS) were 70.8% and 63.9% at 5 years. The percentage of histological response to neoadjuvant chemotherapy ranged between 5% and 100% (mean 83%). The agreement between Bologna System and the different percentual cut-offs of histological response to neoadjuvant chemotherapy was high, with kappa statistics of 0.83 for a cut-off of ≥90%; 0.86 for a cut-off of ≥95%; 0.79 for a cut-off of ≥96% and 0.61 for a cut-off of 100%. Statistically higher DFS rates for good responders compared to poor responders were found when using each given system. Model performance indicators showed that Bologna system had a lower AIC score and a higher c-statistics to predict DFS. When the patients classified as good responders using the different percentual cut-offs of histological response to neoadjuvant chemotherapy, were instead re-classified using the Bologna system, statistical differences were noted in DFS within each specific group. Conclusions All scoring tools to evaluate histological response to neoadjuvant chemotherapy offer good predictive value for DFS in localized Ewing’s sarcoma of bone. The Bologna system better stratifies those patients with histological response to neoadjuvant chemotherapy between 90 and 99%, representing a more reliable scoring tool in this subset.

Incidental lymphomas (ILs) are rare and challenging lesions with poorly characterized clinical-epidemiological and histological features. The present study addressed the open issues concerning these tumors, by assessing the clinical-pathological features of 28 consecutive ILs, diagnosed over a 10-year period at a tertiary center for surgical pathology. ILs were more frequently documented in elderly males (mean age at surgery 70.8 years; M/F ratio 3.3), with sharp prevalence of gastrointestinal and urinary tract involvement (22/28 [78.6%] cases). Low-grade B-cell lymphomas outnumbered all other entities, and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) was the most common subtype (18/28 [64.3%] cases). Compared to other ILs, CLL/SLL occurred at older age and was the sole lymphoid neoplasm affecting the urinary tract. In conclusion, ILs are rare lesions, mostly affecting the gastrointestinal and urinary tract of elderly males. The diagnosis of IL is based on a high degree of suspicion and on careful morphological/phenotypic characterization.

Background Neuroendocrine differentiation has been extensively associated with worse prognosis and to mechanisms of therapy resistance in several epithelial cancers. A high prevalence of neuroendocrine differentiation was recently described in V600EBRAF-mutated (BRAFmt) metastatic colorectal cancers (mCRCs) but no data are available about its prognostic impact in this setting. Methods We assessed synaptophysin immunohistochemical expression in a multi-institutional series of 159 BRAFmt mCRCs with matched clinical and pathological information. Tumours were dichotomized as synaptophysin high and low. Overall survival (OS) and progression-free survival (PFS) were evaluated by Kaplan–Meier and log-rank tests. Results Thirty-five tumours (22.0%) showed any level of positivity for synaptophysin, and 18 (11.3%) were characterized by positivity in at least 20% of tumour cells. Four cases resulted 100% synaptophysin positive. The histotype of synaptophysin-positive tumours (i.e. ≥20%) was not otherwise specified in 11 cases (61.1%) and mucinous adenocarcinoma in 4 cases (22.2%). Four cases were DNA mismatch repair deficient (22.2%) and 7 (38.9%) were characterized by a high number of tumour-infiltrating lymphocytes. At multivariate analysis, high synaptophysin expression was a negative independent prognostic factor for both PFS (HR = 2.00, 95% confidence interval [CI] 1.21–3.33, p = 0.006) and OS (HR = 2.27, 95% CI 1.35–3.85, p = 0.001). Conclusions Among BRAFmt mCRCs, synaptophysin-positive tumours are characterized by worse PFS and OS. Further studies should investigate the molecular mechanisms involved in the acquisition of the neuroendocrine phenotype to identify novel-targeted treatment strategies.

Summary Objective To report the exceptional occurrence of ossifying fibromyxoid tumour (OFMT) as a primary bone lesion. OFMT is a rare soft tissue tumour of uncertain differentiation and variable malignant potential, that occurs in adults with a slight male predominance. It is typically located in the subcutis or in the skeletal muscles of the extremities, followed by trunk or head and neck. Methods Two cases of OFMT proven to arise from bone are presented. The first is a 65-year old female with a history of rib “osteosarcoma”, presenting with an inferior lobe left lung mass. The second is a man with a lytic lesion of the 5th cervical vertebra that recurred shortly after resection. Following H&E and immunohistochemical examination, tumour samples were analysed by NGS and by break-apart FISH to detect rearrangement of the PHF1 and TFE3 genes. Results PHF1 gene-rearrangement was identified by FISH on both the primary and the metastatic lesion of first patient. NGS identified a PHF1(intron1) and EPC1 (exon 10) fusion transcript later confirmed by positive PHF1 rearrangement on FISH in the second case. Conclusions The demonstration of PHF1 gene rearrangements represents a fundamental ancillary diagnostic test when presented with challenging examples of OFMT.

Background The objective of this study was to report on a retrospective series of patients with epithelioid hemangioendothelioma (EHE) who received treatment with sirolimus within the Italian Rare Cancer Network. Methods From January 2005, 38 adult patients with advanced EHE received continuous-dosing sirolimus, 5 mg daily, until they developed either toxicity or disease progression. Disease progression in the 6 months before the start of treatment was required. Each pathologic diagnosis was reviewed. The daily dose of sirolimus was adjusted based on plasma levels. Response was retrospectively assessed by local investigators using Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST). Survival was estimated using the Kaplan-Meier method. Results All 38 patients (WW Domain Containing Transcription Regulator 1 [WWTR1]-positive, n = 37; transcription factor E3 [TFE3]-positive, n = 1) had disease progression before starting sirolimus (at baseline, 13 of 38 patients had the presence of serosal effusions and systemic symptoms). Thirty-seven patients were evaluable for response (there was 1 early interruption). The best RECIST responses were a partial response in 4 patients (10.8%), stable disease in 28 patients (75.7%), and disease progression in 5 patients (13.5%). At a 41.5-month median follow-up (interquartile range [IQR], 23.9-56.8 months), the median PFS was 13 months (95% CI, 3.7 months to not estimated [NE]), and the median OS was 18.8 months (95% CI, 10.6 months to NE). In patients who had serosal effusions at baseline, the median PFS was 4.8 months (IQR, 3.5-11.7 months), and the median OS was 10.6 months (IQR, 5.1-13.0 months), compared with 47.8 months (IQR, 11.4 months to NE) and 47.8 months (IQR, 15.7 months to NE), respectively, in patients without serosal effusions. Overall, sirolimus was fairly well tolerated, with 10 patients reporting irregular menstruation/ovary disfunction. Conclusions The current results confirm that sirolimus is active in EHE, leading to prolonged stabilization in most patients who present without serosal effusions. Serosal effusions are confirmed as an unfavorable prognostic sign associated with short survival, and sirolimus displays limited activity in this subgroup.

Objectives/hypothesis The accurate diagnostic assessment of clinically relevant human papillomavirus (HPV) infections in patients with head and neck squamous cell carcinoma represents an urgent unmet medical need. The aim of this study was to determine feasibility, accuracy, and clinical significance of HPV16/18 E6 oncoprotein detection on cytological specimens from oropharyngeal squamous cell carcinoma (OPSCC) and neck lymph node metastasis of SCC from unknown primary tumor (CUP) via a protein immunochromatographic assay. Study design Cross-sectional study. Methods Cytological specimens from primary tumor and neck metastases were collected from 34 patients with OPSCC or CUP and applied to a lateral flow format test that detects HPV16 and HPV18 E6 oncoproteins. E6 oncoprotein positivity or negativity in these specimens was compared to the specimens' "HPV-driven" reference status, defined by presence of HPV-DNA in combination with p16INK4a overexpression and/or HPV E6 seropositivity. Results Eighteen of 29 OPSCC (62%) and three of five CUP (60%) were HPV-driven according to our reference method. The E6 oncoprotein lateral flow test had a sensitivity of 94% (95% CI: 70%-100%) and a specificity of 100% (95% CI: 66%-100%) on primary tumor, and a sensitivity of 88% (95% CI: 64%-99%) and a specificity of 100% (95% CI: 74%-100%) on neck metastases. Test agreement between the E6 lateral flow test and the clinical reference method, HPV-DNA plus p16INK4a was excellent, both for primary lesion and neck metastases. Conclusions We found the detection of HPV16/18 E6 oncoproteins to be a feasible, highly reliable, and low-invasive method to assess "HPV-driven" status in OPSCC and CUP. Level of evidence II Laryngoscope, 131:1042-1048, 2021.

Medulloblastoma is an embryonal neuroepithelial tumor that affects mainly childhood and more rarely adults. Medulloblastoma occurring as multiple nodules at diagnosis is a rare and tricky presentation. Here, we describe the case of a previously healthy 47-year-old woman with multiple posterior fossa cerebellar tumors. Histological, immunohistochemical, and molecular analyses were performed to best characterize the two excised lesions. The histopathological analysis revealed different variants of medulloblastoma in the excised nodules, one being extensive nodularity, rare in adults, and the other desmoplastic/nodular with areas of anaplasia. Immunostains and molecular analysis classified both nodules as SHH medulloblastoma. Adult medulloblastoma is extremely rare. Important differences exist between adult medulloblastoma and medulloblastoma arising in children and infants. Such differences are in location, distribution of histological variants and of molecular subgroups, survival rates, and therapeutic options. An extensive morphological and molecular characterization of such rare tumors is necessary to choice the best-tailored therapy.

Background This study aimed to review the activity of cytotoxic chemotherapy in patients with inflammatory myofibroblastic tumors (IMTs) treated at nine European sarcoma reference centers. Materials and Methods Patients of any age, with histologically proven IMT, treated with anthracycline-based methotrexate plus/minus vinorelbine/vinblastine (MTX-V) or other chemotherapeutic regimens between 1996 and 2018 were retrospectively reviewed. Diagnosis was confirmed at the local level by an expert pathologist. Response was retrospectively assessed by local investigators by RECIST v1.1. Progression-free survival (PFS), relapse-free survival (RFS), and overall survival (OS) were computed by Kaplan-Meier method. Results Thirty-eight patients were included. Twenty-five patients (8 localized, 17 advanced disease) received an anthracycline-based regimen; 21 were evaluable for response. Overall response rate (ORR) was 10/21 (47.6%). At a 70.8-month median follow-up (FU), median RFS and median OS were not reached (NR) in patients with localized disease; median PFS and median OS were 6.3 (interquartile range [IQR]: 1.9–13.4) and 21.2 (IQR: 7.7–40.7) months in patients with advanced disease. Thirteen patients received MTX-V (4 localized, 9 advanced disease), all evaluable for response. ORR was 7/13 (53.8%). At a 56.6-month median FU, median RFS and median OS were 42.5 (IQR: 12.9–61.2) months and NR (no death events) in patients with localized disease, and NR (IQR: 24.9 to NR) and 83.4 months (IQR: 83.4 to NR) in patients with advanced disease. In the “other-regimens group,” responses were seen in 3/4 patients treated with oral cyclophosphamide and 1/2 with docetaxel/gemcitabine. Conclusion Anthracycline-based and MTX-V regimens are very effective in IMT, with a similar ORR in both groups. MTX-V achieved a prolonged disease control. Responses were also seen with oral cyclophosphamide and docetaxel/gemcitabine, but few patients were treated with these schedules. Implications for Practice Inflammatory myofibroblastic tumor (IMT) is an ultrarare sarcoma with known sensitivity to anaplastic lymphoma kinase (ALK) inhibitors in ALK-fused cases, although ALK inhibitors are not licensed in the disease. The current knowledge on the activity of cytotoxic chemotherapy is limited. This multi-institutional retrospective study on pediatric and adult patients with IMT shows that cytotoxic chemotherapy, and in particular anthracycline-based and methotrexate plus/minus vinorelbine/vinblastine regimens, represents a treatment option and can be considered in IMT patients irrespectively from ALK status. This study provides a benchmark for future studies on new medical therapies.

Lipoblastoma-like tumor is a very rare mesenchymal tumor believed to be restricted to female patients and only recently reported in the spermatic cord of a male patient. We describe herein an additional case of lipoblastoma-like tumor occurring in the spermatic cord, describing its histopathological, immunohistochemical, and molecular features.

Introduction This case-series is aimed to describe the natural history of epithelioid sarcoma (ES) and to provide insights into the differential clinical behaviour of its two variants (“classic-type” and “proximal-type”). The value of a subtype-adapted grading system based on pathological features is explored. Methods Data from consecutive, primary, localised, INI1-deleted ES operated at three Italian sarcoma reference centres (1995–2015) were included. Centralised pathological review was performed. Classic-type ES was broken down into “high-grade” and “low-grade”, according to number of mitoses, evidence of necrosis and nuclear atypia. Five- and 10-year overall survival (OS) and crude cumulative incidence (CCI) of local recurrence (LR) and distant metastasis (DM) were estimated. Results Fifty-two patients were included. 5- and 10-year OS estimates were 70% and 47% in the whole series, 57% and 37% in patients with proximal-type ES, 77% and 54% in patients with classic-type ES (P = 0.02). In classic-type ES, 5- and 10-year OS was higher for low-grade (95% and 72%, respectively) than high-grade tumours (P = 0.002). 5- and 10-year CCI estimates for LR were 21% and 33% in the whole series. 5- and 10-year CCI estimates for DM were 35% and 39% in the whole series, both 28% in classic-type ES, 47% and 59% in proximal-type ES (P = 0.03). Conclusions Suffering from a proximal- or a classic-type is the stronger predictor of outcome in patients with localised ES, with proximal-type ES patients having lower survival due to a higher tendency toward metastatic spreading. However, the “high-grade” classic-type ES was associated with outcomes close to proximal-type ES.

Purpose The aim of our study was to evaluate the prevalence of different HPV genera—alpha, beta and gamma—in Juvenile onset Recurrent Respiratory Papillomatosis (JoRRP) and examine the association of type and genus-specific viral features with the clinical outcome of disease. Methods This retrospective observational study included consecutive patients with JoRRP who were treated in a referral centre between October 2000 and October 2020. All patients underwent cold excision and laser vaporisation of papillomatous lesions. Samples were analysed for the presence of 120 viral genotypes (22 alpha-HPV, 46 beta-HPV, 52 gamma-HPV) using a highly sensitive multiplex genotyping assay. Results Twenty patients with JoRRP, aged 0.3–11 years, were included, with a median follow-up of 13.5 years. All samples were HPV DNA positive: 20 (100%) for alpha-HPV DNA; 7 (35%) for beta—HPV DNA; 0 for gamma-HPV DNA. Three groups were defined according to the number of infections: seven cases (35%) with HPV mono-infection; ten cases (50%) with HPV double-infection; three cases (15%) with ≥ 3 HPV infections. At diagnosis, patients with ≥ 3 HPV infections reported higher median Derkay’s score than those with mono-infection (21 vs 14, P = 0.018). Number of HPV infections was also associated with clinical outcomes, with an average of 0.5 surgical procedures/year in patients with mono-infection, 1.2 for double-infection, 2.6 for ≥ 3 infections (P = 0.006). Conclusion Despite the small sample size, these preliminary data support an association between the number of different alpha and beta HPV co-infections and the clinical severity of the disease.

[Background] The value of neoadjuvant chemotherapy in soft tissue sarcoma (STS) is not completely understood. This study investigated the benefit of neoadjuvant chemotherapy according to prognostic stratification based on the Sarculator nomogram for STS., [Methods] This study analyzed data from ISG-STS 1001, a randomized study that tested 3 cycles of neoadjuvant anthracycline plus ifosfamide (AI) or histology-tailored (HT) chemotherapy in adult patients with STS. The 10-year predicted overall survival (pr-OS) was estimated with the Sarculator and was stratified into higher (10-year pr-OS < 60%) and lower risk subgroups (10-year pr-OS ≥ 60%)., [Results] The median pr-OS was 0.63 (interquartile range [IQR], 0.51-0.72) for the entire study population, 0.62 (IQR, 0.51-0.70) for the AI arm, and 0.64 (IQR, 0.51-0.73) for the HT arm. Three- and 5-year overall survival (OS) were 0.86 (95% confidence interval [CI], 0.82-0.93) and 0.81 (95% CI, 0.71-0.86) in lower risk patients and 0.69 (95% CI, 0.70-0.85) and 0.59 (95% CI, 0.51-0.72) in the higher risk patients (log-rank test, P = .004). In higher risk patients, the 3- and 5-year Sarculator-predicted and study-observed OS rates were 0.68 and 0.58, respectively, and 0.85 and 0.66, respectively, in the AI arm (P = .04); the corresponding figures in the HT arm were 0.69 and 0.60, respectively, and 0.69 and 0.55, respectively (P > .99). In lower risk patients, the 3- and 5-year Sarculator-predicted and study-observed OS rates were 0.85 and 0.80, respectively, and 0.89 and 0.82, respectively, in the AI arm (P = .507); the corresponding figures in the HT arm were 0.87 and 0.81, respectively, and 0.86 and 0.74, respectively (P = .105)., [Conclusions] High-risk patients treated with AI performed better than predicted, and this adds to the evidence for the efficacy of neoadjuvant AI in STS., This was a nonfunded analysis. In the ISG-STS 1001 trial, PharmaMar provided trabectedin for the HG-MRLPS cohort. That trial was partially funded through a European Union grant (EUROSARC FP7 278472).

[Purpose] The effect of high-dose imatinib (800 mg/day) on survival in the adjuvant treatment of patients with resected KIT exon 9–mutated gastrointestinal stromal tumors (GIST) is not established. Here, the association of dose and other clinicopathologic variables with survival was evaluated in a large multi-institutional European cohort., [Experimental Design] Data from 185 patients were retrospectively collected in 23 European GIST reference centers. Propensity score matching (PSM) and inverse-probability of treatment weighting (IPTW) were used to account for confounders. Univariate and multivariate unweighted and weighted Cox proportional hazard regression models were estimated for relapse-free survival (RFS), modified-RFS (mRFS) and imatinib failure-free survival (IFFS). Univariate Cox models were estimated for overall survival., [Results] Of the 185 patients, 131 (70.8%) received a starting dose of 400 mg/d and the remaining 54 (29.2%) a dose of 800 mg/d. Baseline characteristics were partially unbalanced, suggesting a potential selection bias. PSM and IPTW analyses showed no advantage of imatinib 800 mg/d. In the weighted multivariate Cox models, high-dose imatinib was not associated with the survival outcomes [RFS: hazard ratio (HR), 1.24; 95% confidence interval (CI), 0.79–1.94; mRFS: HR, 1.69; 95% CI, 0.92–3.10; IFFS: HR, 1.35; 95% CI, 0.79–2.28]. The variables consistently associated with worse survival outcomes were high mitotic index and nongastric tumor location., [Conclusions] In this retrospective series of patients with KIT exon 9–mutated GIST treated with adjuvant imatinib, a daily dose of 800 mg versus 400 mg did not show better results in terms of survival outcomes. Prospective evaluation of the more appropriate adjuvant treatment in this setting is warranted.

MRP-1 is implicated in multidrug resistance and was described as prognostic in high-risk patients with soft-tissue sarcoma (STS) in a previous study. The current research aimed to validate MRP-1 prognostic/predictive value in localized sarcomas treated with anthracyclines plus ifosfamide within the ISG-1001 phase III study. In addition, the inhibitory activity on MRP-1 was investigated in preclinical studies to identify new combinations able to increase the efficacy of standard chemotherapy in STS. MRP-1 expression was assessed by IHC in tissue microarrays from patients with STS and tested for correlation with disease-free survival (DFS) and overall survival (OS). In vitro studies tested the efficacy of MRP-1 inhibitors (nilotinib, ripretinib, selumetinib, and avapritinib) in sarcoma cell lines. The effect of combinations of the most active MRP-1 inhibitors and chemotherapy was measured on the basis of apoptosis. MRP-1 was evaluable in 231 of 264 cases who entered the study. MRP-1 expression (strong intensity) was independently associated with worse DFS [HR, 1.78; 95% confidence interval (CI), 1.11–2.83; P = 0.016], in the multivariate analysis, with a trend for a worse OS (HR, 1.78; 95% CI, 0.97–3.25; P = 0.062). In vitro studies showed that the addition of MRP-1 inhibitors (nilotinib or avapritinib) to doxorubicin plus palifosfamide, significantly increased cell death in SK-UT-1 and CP0024 cell lines. MRP-1 is an adverse predictive factor in localized high-risk patients with STS treated with neoadjuvant anthracyclines plus ifosfamide followed by surgery. In vitro findings support the clinical assessment of the combination of chemotherapy and MRP-1 inhibitors as a promising strategy to overcome the drug ceiling effect for chemotherapy., The study was partially funded through a European Union grant (EUROSARC FP7 278472). The authors would like to thank Patricio Ledesma Figueroa for Data Management. J. Martin-Broto, D.S. Moura and N. Hindi would like to thank the International Accelerator Award funded by Cancer Research UK [C56167/A29363], Associazione Italiana per la Ricerca sul Cancro [AIRC - 24297] and Fundacion Científica – Asociacion Espanola Contra el Cancer [Foundation AECC - GEACC19007MA]. D.S. Moura was supported by a Sara Borrell grant (CD20/00155) funded by the Instituto de Salud Carlos III. C. Romagosa was supported by a grant from the “Programa d'impuls del talent i de l'ocupabilitat del PERIS 2016–2020.” J-Y. Blay would like to express gratitude for the support from NetSARC (INCA and DGOS) EURACAN (EC 739521) and LYRICAN (INCA-DGOS-INSERM 12563). The ISH1001 study was supported by Eurosarc (FP7–278742).

ObjectiveTo date, no useful prognostic biomarker exists for patients with oral squamous cell carcinoma (OCSCC), a tumour with uncertain biological behaviour and subsequent unpredictable clinical course. We aim to investigate the prognostic significance of two recurrent somatic mutations (-124 C>T and -146 C>T) within the promoter of telomerase reverse transcriptase (TERT) gene and the impact of TERT single nucleotide polymorphism (SNP) rs2853669 in patients surgically treated for OCSCC.MethodsThe genetic frequencies of rs2853669, -124 C>T and -146 C>T as well as the telomere length were investigated in 144 tumours and 57 normal adjacent mucosal (AM) specimens from OCSCC patients.ResultsForty-five tumours harboured TERT promoter mutations (31.3%), with -124 C>T and -146 C>T accounting for 64.4% and 35.6% of the alterations respectively. Patients with -124 C>T TERT promoter mutated tumours had the shortest telomeres in the AM (p=0.016) and showed higher risk of local recurrence (hazard ratio [HR]:2.75, p=0.0143), death (HR:2.71, p=0.0079) and disease progression (HR:2.71, p=0.0024) with the effect being potentiated by the co-occurrence of T/T genotype of rs2853669.Conclusion-124 C>T TERT promoter mutation as well as the T/T genotype of the rs2853669 SNP are attractive independent prognostic biomarkers in patients surgically treated for OCSCC, with the coexistence of these genetic variants showing a synergistic impact on the aggressiveness of the disease.

The tight junction protein claudin-18 (CLDN18), is often expressed in various cancer types including gastric (GC) and gastroesophageal adenocarcinomas (GECs). In the last years, the isoform CLDN18.2 emerged as a potential drug target in metastatic GCs, leading to the development of monoclonal antibodies against this protein. CLDN18.2 is the dominant isoform of CLDN18 in normal gastric and gastric cancer tissues. In this work, we evaluated the immunohistochemical (IHC) profile of CLDN18 and its correlation with clinical and histopathological features including p53, E-cadherin, MSH2, MSH6, MLH1, PMS2, HER2, EBER and PD-L1 combined positive score, in a large real-world and mono-institutional series of advanced GCs (n = 280) and GECs (n = 70). The association of IHC results with survival outcomes was also investigated. High membranous CLDN18 expression (2+ and 3+ intensity ≥75%) was found in 117/350 (33.4%) samples analyzed. CLDN18 expression correlated with age &lt, 70 (p = 0.0035), positive EBV status (p = 0.002), high stage (III, IV) at diagnosis (p = 0.003), peritoneal involvement (p &lt, 0.001) and lower incidence of liver metastases (p = 0.013). CLDN18 did not correlate with overall survival. The predictive value of response of CLDN18 to targeted agents is under investigation in several clinical trials and further studies will be needed to select patients who could benefit from these therapies.

Histiocytic proliferations are heterogeneous lesions with distinct pathogenic and clinical-pathological features. While many of these conditions are nonspecific immune responses to variable causes, a minority of them is associated with specific etiological factors and unique clinical-pathological pictures. By presenting a rare case of Whipple adenopathy, we address the peculiar histological features of this condition and the differential diagnosis of nodal histiocytosis in general.

Chordoma is an exceedingly rare subtype of bone sarcoma. This review aims to provide a comprehensive insight into chordoma epidemiology, and an update on the recent advances in disease, biology and medical therapies.The incidence of chordoma is approximately 0.08/100 000 and the 5-year overall age-adjusted relative survival is 72% in the United States and 61% in Europe. Over the last years, significant steps forwards have been done in the comprehension of chordoma complexity, with insights gained into the biology and morphology of this disease. New entities have been described and potentially druggable molecular targets identified. This is becoming all the more relevant today, as new potentially active agents are under development.Chordoma is a complex disease because of its rarity, biological heterogeneity and peculiar clinical behaviour. Despite the progress done, the outcome in this disease remains unsatisfactory and the identification of active systemic treatments remains an urgent, unmet medical need.

Background: Interferon gamma (IFNγ) and tumor necrosis factor-related weak inducer of apoptosis (TWEAK) molecules seem to have a potential effect on angiogenic factors such as vascular endothelial growth factor (VEGF). The aim of this study was to assess a possible interplay between IFNγ and TWEAK cytokines and VEGF machinery in the different steps of colorectal carcinogenesis. Methods: A total of 92 subjects with colonic adenoma or cancer who underwent screening colonoscopy or surgery were prospectively enrolled. Polypoid lesion tissue samples were collected and frozen. Real-time reverse transcription polymerase chain reaction for IFNγ, TWEAK, and VEGF-A mRNA expression was performed. Immunoassays for VEGF-A, VEGF-C, VEGFR-1, VEGFR-2, and VEGFR-3 were also performed. Nonparametric statistics, receiver operating characteristic curve analysis, and logistic multiple regression analysis were used. Results: IFNγ and TWEAK mRNA expression was higher in patients with T2 or more advanced colorectal cancer than in those with adenomas or T1 cancer (p < 0.001 and p = 0.01, respectively). IFNγ and TWEAK mRNA expression levels directly correlated with VEGF-A mRNA expression levels (rho = 0.44, p < 0.001 and rho = 0.29, p = 0.004, respectively). On the contrary, IFNγ and TWEAK mRNA expression levels inversely correlated with VEGF-C protein levels (rho = –0.29, p = 0.04 and rho = –0.31, p = 0.03, respectively). Similarly, IFNγ and TWEAK mRNA expression levels inversely correlated with VEGFR2 protein levels (rho = –0.38, p = 0.033 and rho = –0.40, p = 0.025, respectively). Conclusion: This study showed that in colorectal polypoid lesions, IFNγ and TWEAK expressions are directly correlated to VEGF-A expression but inversely correlated with VEGFR2 levels, suggesting a possible feedback mechanism in the regulation of VEGF-A expression.

Purpose The aim of our study is to evaluate the prevalence of different HPV genera – alpha, beta and gamma – in Juvenile onset Recurrent Respiratory Papillomatosis (JoRRP) and examine the association of type and genus-specific viral features with the clinical outcome of disease. Methods This retrospective observational study includes consecutive patients with JoRRP who were treated in a referral centre between October 2000 and October 2020. All patients underwent cold excision and laser vaporization of papillomatous lesions. Samples were analysed for the presence of 120 viral genotypes (22 alpha-HPV, 46 beta-HPV, 52 gamma-HPV) using a highly sensitive multiplex genotyping assay. Results Twenty patients with JoRRP, aged 0.3–11 years old, were included, with a median follow-up of 13.5 years. All samples were HPV DNA positive: 20 (100%) for alpha-HPV DNA; 7 (35%) for beta – HPV DNA; 0 for gamma-HPV DNA. Three groups were defined according to the number of infections: seven cases (35%) with HPV mono-infection; ten cases (50%) with HPV double-infection; three cases (15%) with ≥ 3 HPV infections. At diagnosis, patients with ≥ 3 HPV infections reported higher median Derkay’s score than those with mono-infection (21 vs 14, P = 0.018). Number of HPV infections was also associated with clinical outcomes, with an average of 0.5 surgical procedures/year in patients with mono-infection, 1.2 for double-infection, 2.6 for ≥ 3 infections (P = 0.006). Conclusion Despite the small sample size, these preliminary data support an association between the number of different alpha and beta HPV co-infections and the clinical severity of the disease.

Simple Summary Solitary fibrous tumors arising from the bone are an extremely rare event and only few cases have been previously described in the literature. It is characterized by a prominent, branched vascularization, with a thin and dilated vascular texture defined as “staghorn” and by the presence of the NAB2-STAT6 gene rearrangement, present in about 90% of cases and considered a pathognomonic feature. In the present study, we described our series of 24 cases of primary solitary fibrous tumor of the bone to find any clinical and molecular prognostic factors and to compare them with those currently used for soft tissue solitary fibrous tumor and to evaluate the risk stratification system proposed by Demicco, in order to understand whether this system was able to correctly predict the risk of local and distant metastatic relapse even in the case of solitary fibrous tumor of the bone. Abstract Primary solitary fibrous tumor (SFT) of the bone is extremely rare, with only few cases reported in the literature. We retrieved all cases of primary SFT of the bone treated at our institution and we assessed the morphology and the immunohistochemical and molecular features to investigate the clinical outcome of primary SFT of the bone and any clinical relevance of clinical and histological criteria of aggressiveness currently adopted for the soft tissues counterpart. Morphologically, 15 cases evidenced high cellularity, cytologic atypia, and foci of necrosis and were associated with more than 4 mitotic figures/10 HPF. Immunohistochemical analysis showed an expression of CD34 and of STAT6 immunopositivity in 95% and in 100% of cases, respectively. The presence of NAB2-STAT6 chimeric transcripts was found in 10 out of 12 cases in which RT-PCR analysis was feasible, whereas TERT promoter mutations analysis was feasible in 16 cases and only a C-to-T substitution in a heterozygous state was found in one DNA sample for the C228T genetic variant. P53 variants were assessed in 12 cases: 11 (91.6%) cases showed a variation, while in one case, no alteration was found. Disease-specific survival was 64% at 5 years and 49% at 10 years. Statistical analysis showed no correlation between survival and all the clinicopathological and molecular parameters evaluated. In conclusion, at difference to SFT of soft tissues, aggressive behavior of primary SFT of the bone seems to be independent from mitotic count or any other clinicopathological and molecular features.

The unsatisfactory cure rate of relapsing ALK-positive Anaplastic Large-Cell Lymphoma (ALCL) of childhood calls for the identification of new prognostic markers. Here, the small RNA landscape of pediatric ALK-positive ALCL was defined by RNA sequencing. Overall, 121 miRNAs were significantly dysregulated in ALCL compared to non-neoplastic lymph nodes. The most up-regulated miRNA was miR-21-5p, whereas miR-19a-3p and miR-214-5p were reduced in ALCL. Characterization of miRNA expression in cases that relapsed after first line therapy disclosed a significant association between miR-214-5p down-regulation and aggressive non-common histology. Our results suggest that miR-214-5p level may help to refine the prognostic stratification of pediatric ALK-positive ALCL.

Background Melanoma of unknown primary (MUP), accounts for up to 3% of all melanomas and consists of a histologically confirmed melanoma metastasis to either lymph nodes, (sub)cutaneous tissue, or visceral sites without any evidence of a primary cutaneous, ocular, or mucosal melanoma. This study aimed to investigate the characteristics, treatment strategies, and prognostic factors of MUP patients, in order to shed some light on the clinical behavior of this malignancy. Methods All the consecutive patients with a diagnosis of MUP referring to our institutions between 1985 and 2018 were considered in this retrospective cohort study. The records of 173 patients with a suspected diagnosis of MUP were retrospectively evaluated for inclusion in the study. Patient selection was performed according to the Das Gupta criteria, and a total of 127 MUP patients were finally included in the study, representing 2.7% of the patients diagnosed with melanoma skin cancer at our institutions during the same study period. A second cohort of all consecutive 417 MKP patients with AJCC stages IIIB-IV, referring tions in the period considered (1985-2018), was included in the study to compare survival between MUP and MKP patients. All the diagnoses were based on histopathologic, cytologic and immunohistochemical examination of the metastases. All tumors were re-staged according to the 2018 American Joint Committee on Cancer (AJCC) 8th Edition. Results Median follow-up was 32 months (IQR: 15-84). 3-year progression-free survival (PFS) was 54%, while 3-year overall survival (OS) was 62%. Worse OS and PFS were associated with older age (P = 0.0001 for OS; P = 0.008 for PFS), stage IV (P < 0.0001 for OS; P = 0.0001 for PFS) and higher Charlson Comorbidity Index (P < 0.0001 for OS and P = 0.01 for PFS). Patients with lymph node disease showed longer PFS (P = 0.001) and OS (P = 0.0008) than those with (sub)cutis disease. Complete lymph node dissection (CLND) was the most common surgical treatment; a worse OS in these patients was associated with the number of positive lymph nodes (P = 0.01), without significant association with the number of retrieved lymph nodes (P = 0.79). Survival rates were lower in patients undergoing chemotherapy (CT) and target therapy (TT), and higher in those receiving immunotherapy (IT). 417 patients with AJCC stages IIIB-IV of Melanoma Known Primary (MKP) were included for the survival comparison with MUP. 3-year PFS rates were 54 and 58% in MUP and MKP, respectively (P = 0.30); 3-year OS rates were 62 and 70% in MUP and MKP, respectively (P = 0.40). Conclusions The most common clinical scenario of our series was a male patient around 59 years with lymph node disease. We report that CLND associated with IT was the best treatment in terms of survival outcome. In the current era of IT and TT for melanoma, new studies have to clarify the impact of novel drugs on MUP.

The knowledge of the molecular landscape of ileal neuroendocrine tumors (NETs) is affected by the lack of systematic studies investigating intra-tumoral heterogeneity. In this study, intra-tumoral heterogeneity was investigated in 27 primary ileal G1-NETs and their matched nodal and liver metastases in order to assess the tumor grading, the expression status of two somatostatin receptor isoforms (i.e. SSTR2A and SSTR5) and mTOR signaling dysregulation (ph-mTOR, ph-p70S6K, ph-4EBP1, PTEN and miR-21). Among the 27 G1 primary tumors, 4 shifted to G2 in the matched liver metastasis. Although mTOR activation was pretty consistent between primary and secondary malignancies, mTOR effectors (ph-p70S6K and ph-4EBP1) were overexpressed in matched liver metastases, whereas PTEN expression profile changed in only two cases. MiR-21 was significantly up-regulated in the metastatic setting. Although SSTRs expression was present in most of the primary tumors and matched metastasis, we found SSTR5 expression to be significantly increased in liver metastases. Notably, SSTRs expression was heterogeneous within the same lesions in most of the lesions. Overall, despite primary and metastatic ileal NETs show a similar molecular landscape, tumor grading and mTOR signaling pathway may diverge in the metastatic setting, thus affecting prognosis and treatment.

Background Among sarcomas, which are rare cancers, many types are exceedingly rare; however, a definition of ultra-rare cancers has not been established. The problem of ultra-rare sarcomas is particularly relevant because they represent unique diseases, and their rarity poses major challenges for diagnosis, understanding disease biology, generating clinical evidence to support new drug development, and achieving formal authorization for novel therapies. Methods The Connective Tissue Oncology Society promoted a consensus effort in November 2019 to establish how to define ultra-rare sarcomas through expert consensus and epidemiologic data and to work out a comprehensive list of these diseases. The list of ultra-rare sarcomas was based on the 2020 World Health Organization classification, The incidence rates were estimated using the Information Network on Rare Cancers (RARECARENet) database and NETSARC (the French Sarcoma Network's clinical-pathologic registry). Incidence rates were further validated in collaboration with the Asian cancer registries of Japan, Korea, and Taiwan. Results It was agreed that the best criterion for a definition of ultra-rare sarcomas would be incidence. Ultra-rare sarcomas were defined as those with an incidence of approximately ≤1 per 1,000,000, to include those entities whose rarity renders them extremely difficult to conduct well powered, prospective clinical studies. On the basis of this threshold, a list of ultra-rare sarcomas was defined, which comprised 56 soft tissue sarcoma types and 21 bone sarcoma types. Conclusions Altogether, the incidence of ultra-rare sarcomas accounts for roughly 20% of all soft tissue and bone sarcomas. This confirms that the challenges inherent in ultra-rare sarcomas affect large numbers of patients.

Background. We previously showed that grading can prognosticate the outcome of retroperitoneal liposarcoma (LPS). In the present study, we aimed to explore the impact of pathological stratification using grading on the clinical outcomes of patients with advanced well-differentiated LPS (WDLPS) and dedifferentiated LPS (DDLPS) treated with trabectedin. Patients: We included patients with advanced WDLPS and DDLPS treated with trabectedin at the Fondazione IRCCS Istituto Nazionale dei Tumori between April 2003 and November 2019. Tumors were categorized in WDLPS, low-grade DDLPS, and high-grade DDLPS according to the 2020 WHO classification. Patients were divided in two cohorts: Low-grade (WDLPS/low-grade DDLPS) and high-grade (high-grade DDLPS). Results: A total of 49 patients were included: 17 (35%) in the low-grade cohort and 32 (65%) in the high-grade cohort. Response rate was 47% in the low-grade cohort versus 9.4% in the high-grade cohort (logistic regression p = 0.006). Median progression-free survival (PFS) was 13.7 months in the low-grade cohort and 3.2 months in the high-grade cohort. Grading was confirmed as an independent predictor of PFS in the Cox proportional-hazards regression multivariable model (adjusted hazard ratio low-grade vs. high-grade: 0.45, 95% confidence interval: 0.22–0.94, adjusted p = 0.035). Conclusions: In this retrospective case series, sensitivity to trabectedin was higher in WDLPS/low-grade DDLPS than in high-grade DDLPS. If confirmed in larger series, grading could represent an effective tool to personalize the treatment with trabectedin in patients with advanced LPS.

Purpose Non-neuroendocrine neoplasms of the appendix are a phenotypically heterogeneous group of lesions; a comprehensive molecular characterization of these tumors is still lacking. Methods A total of 52 samples taken from 49 patients was evaluated: 18 sessile serrated lesions (SSL; 3 with dysplasia), 2 high-grade tubular adenomas, 1 tubulo-villous adenoma,1 hyperplastic polyp, 18 low-grade appendiceal mucinous neoplasms (LAMN), 3 high-grade appendiceal mucinous neoplasms (HAMN) and 9 mucinous adenocarcinomas. Hotspot mutational profiling of the RNF43, SMAD4, KRAS, NRAS, BRAF and PIK3CA genes was performed. Expression of p53, MLH1, PMS2, MSH2, and MSH6 was evaluated by immunohistochemistry. Results KRAS was the most frequently mutated gene (53.9% of cases), followed by RNF43 (15.4%), and BRAF (13.5%). In particular: KRAS was mutated in 44.4% of adenocarcinomas, 66.7% of HAMNs, 61.1% of LAMNs, 53.3% of SSL without dysplasia and in 66.7% of SSL with dysplasia; RNF43 was mutated in 33.3% of adenocarcinomas, 66.7% of HAMNs, 11.1% of LAMNs and in 6.7% of SSL without dysplasia; BRAF was mutated in 11.1% of adenocarcinomas, 26.7% of SSL without dysplasia and in 5.6% of LAMNs. Only a case of high-grade tubular adenoma showed mismatch repair deficiency, while immunohistochemical expression of p53 was altered in 21.1% of cases. Conclusions The histological phenotypic similarities between appendicular mucinous lesions and serrated colon lesions do not reflect a similar genetic landscape. Mismatch repair deficiency is a rare event during appendiceal mucinous carcinogenesis.

PURPOSE More than 50% of patients with stage IV colorectal cancer (metastatic colorectal cancer [mCRC]) relapse postresection. The efficacy of postoperative systemic treatment is limited in this setting. Thus, these patients would greatly benefit from the use of a reliable prognostic biomarker, such as circulating tumor DNA (ctDNA) to identify minimal or molecular residual disease (MRD). PATIENTS AND METHODS We analyzed a cohort of 112 patients with mCRC who had undergone metastatic resection with curative intent as part of the PREDATOR clinical trial. The study evaluated the prognostic value of ctDNA, correlating MRD status postsurgery with clinical outcomes by using a personalized and tumor-informed ctDNA assay (bespoke multiple PCR, next-generation sequencing assay). Postresection, systemic therapy was given to 39.2% of the patients at the discretion of the treating physician. RESULTS Postsurgical, MRD positivity was observed in 54.4% (61 of 112) of patients, of which 96.7% (59 of 61) progressed at the time of data cutoff (hazard ratio [HR]: 5.8; 95% CI, 3.5 to 9.7; P < .001). MRD-positive status was also associated with an inferior overall survival: HR: 16.0; 95% CI, 3.9 to 68.0; P < .001. At the time of analyses, 96% (49 of 51) of patients were alive in the MRD-negative arm compared with 52.4% (32 of 61) in the MRD-positive arm. Patients who did not receive systemic therapy and were MRD-negative in the combined ctDNA analysis at two time points had an overall survival of 100%. In the multivariate analysis, ctDNA-based MRD status was the most significant prognostic factor associated with disease-free survival (HR: 5.78; 95% CI, 3.34 to 10.0; P < .001). CONCLUSION This study confirms that in mCRC undergoing resection of metastases, postoperative MRD analysis is a strong prognostic biomarker. It holds promises for being implemented in clinical decision making, informing clinical trial design, and further translational research.

Distinction of hydatidiform moles (HM) from non-molar (NM) specimens and subclassification of HM as complete hydatidiform mole (CHM) versus partial hydatidiform mole (PHM) are important for clinical practice and investigational studies. The issue of diagnostic reproducibility is still unsolved, the lack of diagnostic accuracy based on morphology is substantial with an important interobserver variability, even between experienced gynecologic pathologists. Many ancillary techniques have been investigated in the last years to refine HM diagnosis. p57 (a paternally imprinted, maternally expressed gene) immunohistochemistry, based on the unique genetics of CHM (purely androgenetic), PHM (diandric triploid), and NM specimens (biparental, with allelic balance) can identify CHMs, which lack p57 expression because of a lack of maternal DNA. However, although its role in HM diagnosis is pivotal, it does not allow the distinction of PHM from NM specimens, both of which express p57 due to the presence of maternal DNA. Molecular genotyping, which compares villous and decidual DNA patterns to determine the parental source and ratios of polymorphic alleles, distinguishes purely androgenetic CHM from diandric triploid PHM, and both of these from NM specimens. Beyond the claim of establishing a "diagnostic truth", exceptions and peculiar genetic scenarios in the origin of rare CHM and PHM should be kept in mind when approaching any ancillary technique. An algorithmic approach, even in settings with limited resources, can help the pathologists in the diagnostic dilemma of diagnosis of first trimester abortions.

Epstein-Barr virus (EBV) infection characterizes a portion of gastric adenocarcinomas. However, since there is lack of evidence of EBV presence in pre-neoplastic lesions of gastric mucosa, the etiologic role of EBV in gastric carcinogenesis is still debated. We report an unusual case of an EBV-associated foveolar gastric dysplasia associated with a focus of EBV-positive low-grade tubular adenocarcinoma, arisen in the context of a lymphocytic-like (EBV-positive) gastritis. The present case offers the unique opportunity to determine whether EBV is an early or late event in gastric cancer development and to evaluate its prevalence in patients with gastric dysplasia. To properly address this question, we investigated EBER expression in a large mono-institutional series of gastric and gastro-esophageal cancers (n = 594) and associated precursor lesions (n = 84). All the selected gastric dysplastic lesions (n = 43) resulted EBV negative. In most cases, EBV is present only in gastric and gastroesophageal junction adenocarcinomas, but not in their precursor lesions. However, the reported case indicates that non-conventional EBV-associated dysplasia may represent a novel histopathological entity in the gastric dysplasia scenario and that EBV could play an early direct role in gastric carcinogenesis.

Background Preclinical and clinical data indicate that p53 expression might modulate the activity of the epidermal growth factor receptor (EGFR), influencing response/resistance to anti-EGFR monoclonal antibodies. However, the association between p53 status and clinical outcome has not been clarified yet. Objective In our study, we evaluated the role of p53 expression in patients with RAS/BRAF wild-type metastatic colorectal cancer (mCRC) receiving irinotecan/cetuximab in an exploratory and a validation cohort. Patients and Methods p53 expression was analysed in patients with RAS/BRAF wild-type mCRC receiving second-line or third-line irinotecan/cetuximab. Survival distribution was assessed by the Kaplan–Meier method, while the log-rank test was used for survival comparison. Results Among 120 patients with RAS/BRAF wild-type mCRC included in our analysis, 52 (59%) and 19 (59%) patients showed p53 overexpression in the exploratory and validation cohort, respectively. In the exploratory cohort, low p53 expression was correlated with better median progression-free survival (hazard ratio 0.39; p < 0.0001), median overall survival (hazard ratio: 0.23; p < 0.0001) and response rate (p < 0.0001). These results were confirmed by data of the validation cohort where we observed better median progression-free survival (hazard ratio: 0.48; p = 0.0399), median overall survival (hazard ratio: 0.26; p = 0.0027) and response rate (p =0.0007) in patients with p53 normal expression mCRC. Conclusions In our study, p53 overexpression was associated with anti-EGFR treatment resistance in patients with RAS/BRAF WT mCRC, as confirmed in a validation cohort. Larger studies are needed to validate the role of p53 and investigate EGFR cross-talk in these patients.

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Malignant gastrointestinal neuroectodermal tumor (M-GNET) and clear cell sarcoma (CCS) of soft tissue represent closely related, extremely rare, malignant mesenchymal neoplasm of uncertain differentiation. Both entities are characterized genetically by the same molecular alterations represented by the presence of EWSR1-ATF1 and, more rarely, EWSR1-CREB1 fusion genes. The latter translocation seems to be more represented in M-GNET that, despite significant morphologic overlap with CCS, tends to lack overt features of melanocytic differentiation. Most M-GNET occur in the lower gastrointestinal tract, whereas occurrence in the upper tract has been reported only exceptionally. The differential diagnosis represents a major challenge, and accurate diagnosis impact significantly on therapeutic planning. We herein report the clinicopathologic features of a molecularly confirmed M-GNET that arose at the base of the tongue and review the pertinent literature.

Few studies have focused on COVID-19 patients' hepatic histopathological features. Many of the described morphological landscapes are non-specific and possibly due to other comorbidities or to Sars-CoV-2-related therapies. We describe the hepatic histopathological findings of 3 liver biopsies obtained from living COVID-19 patients in which active SARS-CoV-2 infection was molecularly confirmed and biopsied because of significant alterations of liver function tests and 25 livers analyzed during COVID-19-related autopsies. Main histopathological findings were (i) the absence of significant biliary tree or vascular damages, (ii) mild/absent lymphocytic hepatitis; (iii) activation of (pigmented) Kupffer cells, (iv) hepatocellular regenerative changes, (v) the presence of steatosis, (vi) sinusoidal ectasia, micro-thrombosis and acinar atrophy in autopsy specimens No viral particle actively infecting the hepatic or endothelial cells was detected at in situ hybridization. The morphological features observed within the hepatic parenchyma are not specific and should be considered as the result of an indirect insult resulting from the viral infection or the adopted therapeutic protocols.

This case report describes the history of a 41 year-old woman with a solid pseudopapillary neoplasm (SPN) of the pancreas and a metachronous abdominal desmoid tumor (DT) that occurred two years after the SPN surgical resection. At next-generation sequencing of 174 cancer-related genes, both neoplasms harbored a CTNNB1 somatic mutation which was different in each tumor. Moreover, two BRCA2 pathogenic mutations were found in both tumors, confirmed as germline by the sequencing of normal tissue. The BRCA2 mutations were c.631G>A, resulting in the amino-acid change p.V211I, and c.7008-2A>T, causing a splice acceptor site loss. However, as the two neoplasms showed neither loss of heterozygosity nor somatic mutation in the second BRCA2 allele, they cannot be considered as BRCA-dependent tumors. Nevertheless, this study highlights the important opportunities opened by extensive tumor molecular profiling. In this particular case, it permitted the detection of BRCA2-germline mutations, essential for addressing the necessary BRCA-related genetic counseling, surveillance, and screening for the patient and her family.

Summary Mesenchymal tumours represent a heterogenous group of neoplasms encopassing benign, intermediate malignancy, and malignant entities. Sarcomas account for approximately 1% of human malignancies. In consideration of their rarity as well as of intrinsic complexity, diagnostic accuracy represents a major challenge. Traditionally, mesenchymal tumours are regarded as lesions the occurrence of which is mostly limited to somatic soft tissues. However, the occurrence of soft tissue tumours at visceral sites represent a well recognized event, and the GI-tract ranks among the most frequently involved visceral location. There exist entities such as gastrointestinal stromal tumours (GIST) and malignant gastointestinal neuroectodermal tumors that exhibit exquisite tropism for the GI-tract. This review will focus also on other relevant clinico-pathologic entities in which occurrence at visceral location is not at all negligible.

Pediatric primary lung carcinomas are extremely rare. Apart from known associations with congenital adenomatoid malformations, cases of primary lung adenocarcinomas after prolonged treatments of pediatric malignancy have been reported. We describe the morphological and molecular features of three cases of lung adenocarcinoma developed in adolescents aged 8 to 17 years during progression of their bone osteosarcoma or Ewing sarcomas. The morphological features overlapped those of adult lung adenocarcinoma including in situ, minimally invasive, and invasive forms. EGFR gene mutations were found in all three cases by targeted next-generation sequencing. The two patients with Ewing sarcoma had no progression of their lung cancer and no further progression of the metastatic bone tumor after additional chemo- and radio-therapy. Conversely, the osteosarcoma patient refused further treatments after thoracic surgery for metastatic osteosarcoma and locally advanced adenocarcinoma and died 2 years later of widespread distant metastases. Our results indicate that primary lung cancer might originate in pediatric patients during prolonged adjuvant therapies for primary bone neoplasm, and this possibility should be considered in the presence of suspected lung disease progression to correctly monitor the primary tumor evolution and define the appropriate therapeutic strategy at each time point. If appropriately treated, second primary lung cancer may not affect the patients' prognosis. The pathogenetic mechanisms of these rare lung adenocarcinomas are not clear, but the presence of EGFR mutations in all three cases indicates an oncogene addiction of the lung tumor, rather than a direct cancerogenic effect of the sarcoma-related treatment.

A complete understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) physiopathology and related histopathologic lesions is necessary to improve treatment and outcome of coronavirus disease 2019 (COVID-19) patients. Many studies have focused on autopsy findings in COVID-19-related deaths to try and define any possible specific pattern. Histopathologic alterations are principally found within lungs and blood vessels, and these abnormalities also seem to have the highest clinical impact. Nevertheless, many of the morphological data collected so far are non-specific, fickle, and possibly associated with other co-existing factors. The aim of this minireview is to describe the main histopathological features related to COVID-19 and the mechanism known as “cytokine storm”.

Aims: To present our experience on spinal sclerosing epithelioid fibrosarcoma (SEF) and review the existing literature pertaining to SEF of the spine. Methods and results: Six cases of spinal SEF were reviewed, and a literature search of all primary SEFs of the spine was performed. All tumours occurred in adults (median age, 41years) and were located all along the spine, the lumbar vertebrae being the most commonly involved. All patients presented with pain that they had experienced for months. The mean tumour size at diagnosis was 52mm. Five tumours showed a spectrum of microscopic features consistent with pure SEF, and one showed a hybrid morphology with areas of low-grade fibromyxoid sarcoma. All were diffusely and strongly positive for mucin 4. Two cases were initially misdiagnosed as epithelioid haemangioendothelioma and aggressive chondroblastoma. Fluorescence in-situ hybridisation showed rearrangements of either FUS or EWSR1 in four cases. Reverse transcription polymerase chain reaction showed the presence of FUS–CREB3L1 and EWSR1–CREB3L1 fusion transcripts in two cases and one case, respectively. Of five patients with follow-up data available, two developed one or more local recurrences and three patients had metastatic disease. Distant metastases were mainly to other osseous locations, followed by lungs and lymph nodes. At last follow-up, three patients had died of disease and one was alive with multiple metastases. Conclusions: SEF is an aggressive sarcoma that can involve the spine. It is important to recognise the spine as the primary location of SEF, in order to avoid misdiagnosis as more common primary spinal neoplasms, which can impact on therapeutic approaches.

Despite the significant achievements in the diagnosis and treatment of metastatic breast cancer (MBC), this condition remains substantially an incurable disease. In recent years, several clinical studies have aimed to identify novel molecular targets, therapeutic strategies, and predictive biomarkers to improve the outcome of women with MBC. Overall, ~40% of hormone receptor (HR)+/HER2− MBC cases harbor alterations affecting the (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. This pathway is a major target in oncogenesis, as it regulates growth, proliferation, cell survival, and angiogenesis. Lately, the pharmacologic targeting of PIK3CA in HR+/HER2− MBC has shown significant benefits after the occurrence of endocrine therapy resistance. The orally available α-selective PIK3CA inhibitor, alpelisib, has been approved in this setting. To perform an optimal patients' selection for this drug, it is crucial to adopt a tailored methodology. Clinically relevant PIK3CA alterations may be detected in several biospecimens (e.g. tissue samples and liquid biopsy) using different techniques (e.g. real-time PCR and next-generation sequencing). In this study, we provide an overview of the role of PIK3CA in breast cancer and of the characterization of its mutational status for appropriate clinical management.

Aims: To evaluate the diagnostic accuracy of SSX and SSX::SS18 antibodies in decalcified surgical specimens and outcome of synovial sarcomas (SS) of bone. Methods and results: Twenty-five cases were classified as bone SS (prevalence 0.32% among malignant primary bone sarcoma). Median age was 34 years (range = 9–79). Twenty-four of 25 patients presented with non-metastatic tumours, one with lung metastases. The majority of tumours involved the long bones of extremities with metaphyseal origin. Mean size of the tumour was 7.1 cm. Twenty cases (80%) were monophasic and five (20%) were biphasic. SS18::SSX fusion-specific antibody had 92% sensitivity and 99% specificity for primary bone SS, whereas SSX C-terminus antibody had 100% sensitivity and 94% specificity. Fluorescence in-situ hybridisation (FISH) analysis was feasible in nine (36%) cases and detected SS18 rearrangement in all nine cases. All patients underwent surgical removal of their primary tumour, with adequate margins in 18 (72%) patients. Chemotherapy with metothrexate, cisplatin, doxorubicin and ifosfamide was used in the seven patients. Two patients with inadequate surgical margins received radiotherapy. With a median follow-up of 80 months (range = 6–428), 5- and 10-year overall survival (OS) was 66.6% and 47.9%, respectively, and 5 and 10 years’ disease-free survival (DFS) was 36.8% [95% confidence interval (CI) = 18.0–55.7%] and 32.2% (95% CI = 14.6–51.2%), respectively. A significant improvement in 10 years’ DFS in patients undergoing chemotherapy compared with patients who did not was observed (P = 0.039). Conclusions: Our series highlights the utility of SS18::SSX fusion-specific and SSX C-terminus antibodies to support the diagnosis of SS. Adjustment chemotherapy was associated with improved prognosis in this series.

Introduction: Spermatic cord sarcomas represent a rare genitourinary malignancy with a challenging diagnostic and therapeutic pathway. Different histotypes have been described and prognostic factors remain poorly defined due to the paucity of data presented in literature. Methods: Retrospective chart review of 22 adult patients treated for spermatic cord sarcoma in a single institution in the last 20 years was performed. Clinicopathological characteristics of the tumors were collected with primary and subsequent treatment. Survival analysis was performed in order to identify prognostic factors of disease-specific survival. Results: The median age at diagnosis was 68 years (58–78), the most common histotype was liposarcoma (14/22), and most patients (63.6%) were found to have positive surgical margins after surgery. The 5-year cancer specific survival was 91.3%. Grading (p = 0.480), histotype (p = 0.327), and type of intervention (p = 0.732) were not associated with survival. All patients dead of disease had positive surgical margins (p = 0.172). Conclusion: We report a good prognosis at 5 years. Wide radical resection remains the first and probably the most important step; thus, according also to literature, negative surgical margins should be aimed.

Intratumoral immune infiltrate was recently reported in gastrointestinal stromal tumors (GISTs). However, the tumor-intrinsic factors that dictate GIST immunogenicity are still largely undefined. To shed light on this issue, a large cohort (82 samples) of primary untreated GISTs, representative of major clinicopathological variables, was investigated by an integrated immunohistochemical, transcriptomic, and computational approach. Our results indicate that tumor genotype, location, and malignant potential concur to shape the immunogenicity of primary naive GISTs. Immune infiltration was greater in overt GISTs compared with that in lesions with limited malignant potential (miniGISTs), in KIT/PDGFRA-mutated tumors compared with that in KIT/PDGFRA WT tumors, and in PDGFRA-mutated compared with KIT-mutated GISTs. Within the KIT-mutated subset, a higher degree of immune colonization was detected in the intestine. Immune hot tumors showed expression patterns compatible with a potentially proficient but curbed antigen-specific immunity, hinting at sensitivity to immunomodulatory treatments. Poorly infiltrated GISTs, primarily KIT/PDGFRA WT intestinal tumors, showed activation of Hedgehog and WNT/β-catenin immune excluding pathways. This finding discloses a potential therapeutic vulnerability, as the targeting of these pathways might prove effective by both inhibiting pro-oncogenic signals and fostering antitumor immune responses. Finally, an intriguing anticorrelation between immune infiltration and ANO1/DOG1 expression was observed, suggesting an immunomodulatory activity for anoctamin-1., Integrated immunohistochemical, transcriptomic and computational analysis of gastrointestinal stromal tumors (GIST) reveal that tumor genotype, location, and malignant potential shape immunogenicity.

Summary Mesenchymal tumours represent one of the most challenging field of diagnostic pathology and refinement of classification schemes plays a key role in improving the quality of pathologic diagnosis and, as a consequence, of therapeutic options. The recent publication of the new WHO classification of Soft Tissue Tumours and Bone represents a major step toward improved standardization of diagnosis. Importantly, the 2020 WHO classification has been opened to expert clinicians that have further contributed to underline the key value of pathologic diagnosis as a rationale for proper treatment. Several relevant advances have been introduced. In the attempt to improve the prediction of clinical behaviour of solitary fibrous tumour, a risk assessment scheme has been implemented. NTRK-rearranged soft tissue tumours are now listed as an “emerging entity” also in consideration of the recent therapeutic developments in terms of NTRK inhibition. This decision has been source of a passionate debate regarding the definition of “tumour entity” as well as the consequences of a “pathology agnostic” approach to precision oncology. In consideration of their distinct clinicopathologic features, undifferentiated round cell sarcomas are now kept separate from Ewing sarcoma and subclassified, according to the underlying gene rearrangements, into three main subgroups (CIC, BCLR and not ETS fused sarcomas) Importantly, In order to avoid potential confusion, tumour entities such as gastrointestinal stroma tumours are addressed homogenously across the different WHO fascicles. Pathologic diagnosis represents the integration of morphologic, immunohistochemical and molecular characteristics and is a key element of clinical decision making. The WHO classification is as a key instrument to promote multidisciplinarity, stimulating pathologists, geneticists and clinicians to join efforts aimed to translate novel pathologic findings into more effective treatments.

The aim of this study is to assess the usefulness of beta-catenin immunohistochemical expression in the differential diagnosis of osteoid-producing primary tumors of bone. Seventy cases of osteoid-producing tumors of bone (24 conventional osteosarcomas, 18 osteoblastomas, 13 osteoblastoma-like osteosarcomas, 10 chondroblastomas, and 5 chondroblastoma-like osteosarcomas) diagnosed at Istituto Ortopedico Rizzoli were reviewed and evaluated for the intensity, extension, and subcellular distribution of immunohistochemical expression of beta-catenin. A majority of cases (73%, 51 cases) exhibited cytoplasmic and/or membranous positivity in varied degrees of intensity and proportion of positive cells, in the absence of nuclear staining. Fifteen cases (21%) were completely negative, including two osteoblastomas, five chondroblastomas, three conventional osteosarcomas, four osteoblastoma-like osteosarcomas, and one chondroblastoma-like osteosarcoma. A minority of cases (6%) including three osteoblastoma-like osteosarcomas and one osteoblastoma showed focal nuclear beta-catenin positivity with or without concomitant cytoplasmic staining. In the current series, beta-catenin showed not to be useful in the differential diagnosis of osteoid-producing primary bone tumors.