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Among skin epithelial tumors, recurrent mutations in the APC/CTNNB1 genes resulting in activation of the Wnt/β-catenin pathway have been reported predominantly in neoplasms with matrical differentiation. In the present study, we describe the morphologic, immunohistochemical, and genetic features of 16 primary cutaneous carcinomas harboring mutations activating the Wnt/β-catenin pathway without evidence of matrical differentiation, as well as 4 combined tumors in which a similar Wnt/β-catenin-activated carcinoma component was associated with Merkel cell carcinoma (MCC) or pilomatrical carcinoma. Among the pure tumor cases, 6 of 16 patients were women with a median age of 80 years (range, 58-98 years). Tumors were located on the head and neck (n = 7, 44%), upper limb (n = 4, 25%), trunk (n = 3, 18%), and leg (n = 2, 13%). Metastatic spread was observed in 4 cases resulting in death from disease in 1 patient. Microscopically, all cases were poorly differentiated neoplasms infiltrating the dermis and/or subcutaneous tissue. In 13 cases, solid "squamoid" areas were associated with a basophilic component characterized by rosette/pseudoglandular formation resulting in a biphasic appearance. Three specimens consisted only of poorly differentiated carcinoma lacking rosette formation. Immunohistochemical studies showed frequent expression of EMA (100%), BerEP4 (100%), cytokeratin 7 (94%), chromogranin A (44%), synaptophysin (82%), and cytokeratin 20 (69%). Complete loss of Rb expression was observed in all but 1 case. Nuclear β-catenin and CDX2 expressions were detected in all cases. Recurrent pathogenic somatic mutations were observed in APC (60%), CTNNB1 (40%), and RB1 (n = 47%). Global methylation analysis confirmed that cases with rosette formation constituted a homogeneous tumor group distinct from established skin tumor entities (pilomatrical carcinoma, MCC, and squamous cell carcinoma), although the 3 other cases lacking such morphologic features did not. In addition, we identified 4 combined neoplasms in which there was a component showing a similar poorly differentiated rosette-forming carcinoma demonstrating Rb loss and β-catenin activation associated with either MCC (n = 3) or pilomatrical carcinoma (n = 1). In conclusion, we describe a distinctive neoplasm, for which we propose the term "Wnt/β-catenin-activated rosette-forming carcinoma," morphologically characterized by the association of rosette formation, squamous and/or neuroendocrine differentiation, diffuse CDX2 expression, Rb loss, and mutations in CTNNB1/APC genes., (Copyright © 2024 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Merkel cell carcinoma (MCC) is an aggressive skin cancer for which Merkel cell polyomavirus integration and expression of viral oncogenes small T and Large T have been identified as major oncogenic determinants. Recently, a component of the PRC2 complex, the histone methyltransferase enhancer of zeste homolog 2 (EZH2) that induces H3K27 trimethylation as a repressive mark has been proposed as a potential therapeutic target in MCC. Because divergent results have been reported for the levels of EZH2 and trimethylation of lysine 27 on histone 3, we analyzed these factors in a large MCC cohort to identify the molecular determinants of EZH2 activity in MCC and to establish MCC cell lines' sensitivity to EZH2 inhibitors. Immunohistochemical expression of EZH2 was observed in 92% of MCC tumors (156 of 170), with higher expression levels in virus-positive than virus-negative tumors (P = 0.026). For the latter, we showed overexpression of EZHIP, a negative regulator of the PRC2 complex. In vitro, ectopic expression of the large T antigen in fibroblasts led to the induction of EZH2 expression, whereas the knockdown of T antigens in MCC cell lines resulted in decreased EZH2 expression. EZH2 inhibition led to selective cytotoxicity on virus-positive MCC cell lines. This study highlights the distinct mechanisms of EZH2 induction between virus-negative and -positive MCC., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

We report 21 cases of trichogerminoma harbouring previously undescribed FOXK1::GRHL1/2 or GPS2::GRHL1/2/3 in-frame fusion transcripts. Microscopic examination of a preliminary set of five cases revealed well-delimitated tumours located in the dermis with frequent extension to the subcutaneous tissue. Tumours presented a massive and nodular architecture and consisted of a proliferation of basaloid cells. A biphasic pattern sometime resulting in tumour cell nests ('cell balls') was present. Immunohistochemistry demonstrated the expression of cytokeratins (CKs) 15, 17, and PHLDA1. In addition, numerous CK20-positive Merkel cells were detected. RNA sequencing (RNA-seq) revealed a FOXK1::GRHL1 chimeric transcript in three cases and a FOXK1::GRHL2 fusion in two cases. In a second series for validation (n = 88), FOXK1::GRHL1/2 fusion transcripts were detected by RT-qPCR or FISH in an additional 12 trichogerminomas and not in any other follicular tumour entities or basal cell carcinoma cases (n = 66). Additional RNA-seq analysis in trichogerminoma cases without detected FOXK1::GRHL1/2 rearrangements revealed GPS2::GRHL1 fusion transcripts in two cases, GPS2::GRHL2 in one case, and GPS2::GRHL3 fusion transcript in one case. Therefore, our study strongly suggests that GRHL1/2/3 gene rearrangements might represent the oncogenic driver in trichogerminoma, a subset of follicular tumours characterized by immature features and numerous Merkel cells. © 2022 The Pathological Society of Great Britain and Ireland., (© 2022 The Pathological Society of Great Britain and Ireland.)

Aims: To evaluate the accuracy of intraoperative frozen section histopathology for diagnosing periprosthetic joint infection (PJI) during hip revision surgery, both for patients with and without recent trauma to the hip., Patients and Methods: The study included all revision total hip replacement procedures where intraoperative frozen section histopathology had been used for the evaluation of infection in a single institution between 2008 and 2015. Musculoskeletal Infection Society criteria were used to define infection. 210 hips were included for evaluation. Prior to revision surgery, 36 hips had a dislocation or a periprosthetic fracture (group A), and 174 did not (group B)., Results: The prevalence of infection was 14.3% (5.6% in group A and 16.1% in group B). Using Feldman criteria, the sensitivity of histopathology was 50.0%, specificity 47.1%, positive predictive value 5.3% and negative predictive value 94.1% in group A. The sensitivity of frozen section histopathology was 75.0%, specificity 96.5%, positive predictive value 85% and negative predictive value 95.3% in group B., Conclusions: Intraoperative frozen section histopathology is reliable for the diagnosis of PJI if no dislocation or periprosthetic fracture has occurred prior to hip revision surgery.

Dialysis-related amyloidosis (DRA) or β2microglobulin (β2m)-amyloidosis is a disorder caused by the inability to clear a protein called β2m in patients with chronic kidney disease. It results in deposition of β2m as amyloid fibrils, most commonly in bones and joints. Infrequently, visceral organs may be involved. With modern high-flux haemodialysis, DRA has become a rare disease, yet it may occur. We present a case of DRA in an 86-year-old woman. This case is particularly notable for its rare presentation as chronic intestinal pseudo-obstruction. It is of paramount importance to recognise this entity in order to reduce delay in treatment and avoid patients being frustrated not getting a diagnosis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

The advent of BRAF-targeted therapies led to increased survival in patients with metastatic melanomas harboring a BRAF V600 mutation (implicated in 46-48% of malignant melanomas). The Idylla(™) System (Idylla(™)), i.e., the real-time-PCR-based Idylla(™) BRAF Mutation Test performed on the fully-automated Idylla(™) platform, enables detection of the most frequent BRAF V600 mutations (V600E/E2/D, V600K/R/M) in tumor material within approximately 90 min and with 1% detection limit. Idylla(™) performance was determined in a multi-center study by analyzing BRAF mutational status of 148 archival formalin-fixed paraffin-embedded (FFPE) tumor samples from malignant melanoma patients, and comparing Idylla(™) results with assessments made by commercial or in-house routine diagnostic methods. Of the 148 samples analyzed, Idylla(™) initially recorded 7 insufficient DNA input calls and 15 results discordant with routine method results. Further analysis learned that the quality of 8 samples was insufficient for Idylla(™) testing, 1 sample had an invalid routine test result, and Idylla(™) results were confirmed in 10 samples. Hence, Idylla(™) identified all mutations present, including 7 not identified by routine methods. Idylla(™) enables fully automated BRAF V600 testing directly on FFPE tumor tissue with increased sensitivity, ease-of-use, and much shorter turnaround time compared to existing diagnostic tests, making it a tool for rapid, simple and highly reliable analysis of therapeutically relevant BRAF mutations, in particular for diagnostic units without molecular expertise and infrastructure.

Rhabdomyosarcomas are classified into three well-defined categories: embryonal, alveolar and pleomorphic rhabdomyosarcoma. Recently, seven cases of an unusual adult type of rhabdomyosarcoma with a prominent hyaline sclerosis have been described. We report the hitherto unreported cytogenetic changes of an adult sclerosing rhabdomyosarcoma. A 79-year-old woman underwent an amputation for a rapidly growing soft tissue mass in the anterior compartment of the right lower leg. The tumor infiltrated the tibia. On histology, a fascicular spindle to round cell proliferation, embedded in a prominent hyaline matrix, was seen. Immunohistochemistry showed focal desmin, myogenin and MyOD1 expression, and electron microscopy revealed Z-band material. Cytogenetic analysis disclosed a 44-49,XX,+del(1)(p22)[2],+11,+16[5],+18[12],+21[3],-22 [cp13] karyotype. Using fluorescent in situ hybridization (FISH) analysis, the tumor cells were negative for FOXO1A-disrupting translocations specific for alveolar rhabdomyosarcoma. The chromosomal composition of malignant cells resembled the pattern of numerical changes frequently observed in embryonal rhabdomyosarcoma, suggesting a close relationship of an adult sclerosing rhabdomyosarcoma with this entity.

Chromosomal aberrations involving chromosome segment 12q13-15 are a common finding in a variety of benign mesenchymal tumors. The target gene encodes for HMGIC, a member of the high mobility group protein family. These proteins act as architectural transcription factors. HMGIC plays a role as a common genetic denominator in benign mesenchymal tumorigenesis. We report a case of hyaline vascular Castleman's disease with intragenic HMGIC rearrangement, due to a clonal cytogenetic aberration involving the long arm of chromosome 12 [46,XX, add(1)(q21),der(6)t(6;12) (q23;q15),add(7)(p22), -9,inv(9)(p11q13),del(12)(q15),+mar] obtained after short-term primary cultures. A combined immunocytologic-cytogenetic approach enabled us to demonstrate the exclusive presence of HMGIC rearrangement in anti-CD21 reactive follicular dendric cells. This finding confirms that a clonal proliferation of follicular dendritic cells occurs in the hyaline vascular variant of Castleman's disease. It also provides a possible molecular pathway explaining stromal overgrowths and stromal neoplasms developing from this disorder.

Introduction: The utility of a routine histopathological examination in aseptic revision total hip arthroplasty (THA) has not been well explored. We aim to describe the approach and present the results of histopathological examination, focusing on its clinical usefulness in the setting of aseptic revision THA. Method: We retrospectively reviewed 285 performed aseptic revision THA with available histopathological reports between 2015 and 2017 at a single institution. We described histopathological requests by the surgical team. Preoperative diagnoses, intraoperative findings, as well as histopathology and culture results were analysed. Results: 13 painful THAs (4.5%) had preoperatively unknown diagnoses. In 10 of them, potential causes of pain were intraoperatively identified. Histopathology confirmed these findings in 8 THAs. 19 THAs (6.7%) revealed unexpected positive cultures (UPC). Histopathology was negative for infection in 18 of them. Among 16 consultants, 3 surgeons requested histopathology in 47% of the cases (130/285), usually to exclude infection (101/285; 35%). Documentation for tissue sample location was lacking in 51% (145/285), and for question asked by the surgeon in 47% (135/285). Conclusions: Histopathology is deemed a useful confirmatory tool in the context of ruling out infection in UPCs, and in documenting intraoperative findings in painful THAs with unknown preoperative diagnoses. Importantly, the approach to requesting histopathology should be optimised. Further large-scale studies, including cost analyses, are warranted to explore the usefulness of histopathology in routine utility. [ABSTRACT FROM AUTHOR]

This article examines the potential link between endometriosis (EMS) and inflammatory bowel disease (IBD) using a method called Mendelian randomization (MR). The study found evidence suggesting a causal relationship between EMS and an increased risk of IBD, particularly Crohn's disease (CD). However, the statistical significance was lost after adjusting for multiple comparisons. The study also found no evidence of a causal relationship between IBD and EMS. The findings shed light on the complex relationship between EMS and IBD, highlighting the need for tailored treatment options for EMS patients at risk of IBD. [Extracted from the article]

Background: Castleman disease (CD) comprises a group of rare and heterogeneous haematological disorders, including unicentric (UCD) and multicentric (MCD) forms, the latter further subdivided into HHV8-MCD, POEMS-MCD and idiopathic-MCD (iMCD). However, according to the Castleman Disease Collaborative Network guidelines, the diagnosis of CD can only be achieved through collaboration between clinicians and pathologists., Methods: We applied these clinical and pathological criteria and implement with clonality testing to a retrospective cohort of 48 adult and paediatric Italian patients diagnosed with reactive lymphadenitis with CD-like histological features., Results: We confirmed the diagnosis of CD in 60% (29/48) of the cases, including 12 (41%) UCD and 17 (59%; five HHV8-MCD, three POEMS-MCD and nine iMCD) MCD. Of the remaining 19 cases (40%) with multiple lymphadenopathy, 5 (26%) were classified as autoimmune diseases, 1 (5%) as autoimmune lymphoproliferative disorder, 1 (5%) as IgG4-related disease, 11 (83%) as reactive lymphadenitis and 1 (5%) as nodal marginal zone lymphoma., Conclusions: Our study emphasizes the importance of the multidisciplinary approach to reactive lymphadenitis with CD-like features in order to achieve a definitive diagnosis and choose the appropriate treatment., (© 2023 The Authors. British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.)

Anti-GBM disease is a rare vasculitis that causes rapid progressive glomerulonephritis and pulmonary haemorrhage. It is usually an adult diagnosis with isolated paediatric cases reported. Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy mainly affecting adults that causes multiorgan ischaemia, microangiopathic haemolytic anaemia, and thrombocytopenia. We present the first paediatric case of concurrent anti-GBM disease and TTP. A 14-year-old boy presented with acute kidney failure and severe pulmonary haemorrhage due to anti-GBM disease, confirmed on auto-antibody testing. There was thrombocytopenia and moderately low ADAMTS13 activity suggestive of TTP. The renal prognosis was poor with a need for dialysis. He was severely unwell with pulmonary haemorrhages requiring the use of extracorporeal membrane oxygenation (ECMO). His disease was treated with corticosteroids, plasma exchange (PEX), rituximab, and cyclophosphamide, resulting in remission. Anti-GBM disease is rare in children but should be considered in those presenting with acute kidney injury, particularly where there has been exposure to pulmonary irritants. An aggressive presentation warrants aggressive treatment with methylprednisolone, PEX, and cyclophosphamide. Rituximab may benefit patients that have concurrent TTP. TTP may exacerbate pulmonary disease, but complete respiratory recovery is possible. Disease relapse is rare in the paediatric age group, and these patients are candidates for kidney transplantation. [ABSTRACT FROM AUTHOR]

Objectives: Castleman disease (CD) is a heterogeneous group of disorders involving systemic inflammation and lymphoproliferation. Recently, clonal mutations have been identified in unicentric CD (UCD) and idiopathic multicentric CD (iMCD), suggesting a potential underlying neoplastic process. Methods: Patients with UCD or iMCD with next generation sequencing (NGS) data on tissue DNA and/or circulating tumor DNA (ctDNA) were included. Results: Five patients were included, 4 with iMCD and 1 with UCD. Four patients (80%) were women; median age was 40 years. Three of five patients (60%) had ≥1 clonal mutation detected on biopsy among the genes included in the panel. One patient with iMCD had a 14q32‐1p35 rearrangement and a der(1)dup(1)(q42q21)del(1)(q42) (1q21 being IL‐6R locus) on karyotype. This patient also had a NF1 K2459fs alteration on ctDNA (0.3%). Another patient with iMCD had a KDM5C Q836* mutation, and one patient with UCD had a TNS3‐ALK fusion but no ALK expression by immunohistochemistry. Conclusions: We report 4 novel somatic alterations found in patients with UCD or iMCD. The 1q21 locus contains IL‐6R, and duplication of this locus may increase IL‐6 expression. These findings suggest that a clonal process may be responsible for the inflammatory phenotype in some patients with UCD and iMCD. [ABSTRACT FROM AUTHOR]

Trigeminal trophic syndrome (TTS) is a rare disorder that presents as ulceration of the nasal ala, and less often ipsilateral cheek, cutaneous lip, and forehead, following damage to the trigeminal nerve. TTS is often very difficult to treat due to anesthesia and paresthesia along the distribution of the trigeminal nerve, which often leads to a large behavioral component of this disease. In this single case report, a thermoplastic mask was sutured in place overlying the chronic ulcerations of TTS in a 57-year-old man. Significant re-epithelization of the chronic ulcerations of TTS was seen after only 6 weeks of thermoplastic mask attachment. While TTS is a chronic and difficult to treat disease, the use of a thermoplastic mask in the treatment of this disease can significantly decrease the self-manipulation component and allow for re-epithelization and healing of the chronic ulcerations. [ABSTRACT FROM AUTHOR]

Background: Spindle cell/sclerosing rhabdomyosarcoma is a genomically heterogeneous, uncommon subtype of rhabdomyosarcoma, particularly rare in adults. Its MYOD1-mutant variant is aggressive irrespective of age. Cytogenetic data on spindle cell/sclerosing rhabdomyosarcoma are sparse and disparate. Materials and Methods: Cytogenetic and molecular analyses were performed on an adult sclerosing rhabdomyosarcoma. Results: The karyotype of the sclerosing rhabdomyosarcoma displayed clonal evolution corresponding to two hyperdiploid clones: 48,XY,+i(19)(p10),+22/ 48,idem, der(9)t(2;9)(q21~22;p21). The changes were gain of chromosome 19 with the overrepresentation of 19p arm, gain of chromosome 22, gain of the 2q arm, and loss of 9p21. Mutation analysis revealed a homozygous c.T365G (p.L122R) mutation of the MYOD1 gene, but none of PIK3CA. Conclusion: To our knowledge, this is the first adult MYOD1- mutant sclerosing rhabdomyosarcoma studied cytogenetically. The only other reported sclerosing rhabdomyosarcoma with MYOD1 mutation and abnormal karyotype was pediatric. Since these tumors are highly aggressive, further studies unravelling their cytogenetic and molecular characteristics are warranted. [ABSTRACT FROM AUTHOR]

Angiosarcoma of the colon is rare, as is colonic amyloidosis. To our knowledge, there have been no reported cases of angiosarcoma arising in association with amyloid deposition. Herein, we described a case of 77-year-old man who presented with hematochezia, and a sigmoid mass was found on colonoscopy. Histologic examination of the resected specimen showed extensive nodular deposition of AL-lambda amyloid material in the colonic wall, as well as high-grade angiosarcoma which was closely intermingled with the amyloid deposits. While the occurrence of both colonic amyloidosis and angiosarcoma in this patient may represent pure coincidence, given the intimate association of the angiosarcoma and the amyloid deposition and the rarity of both of these lesions, we hypothesize that angiosarcoma could be secondary to amyloid deposition. [ABSTRACT FROM AUTHOR]

Purpose: We conducted a systematic review and meta-analysis to examine the role of inflammatory bowel disease (IBD) in ovarian reserve functions., Methods: The PECO strategy was employed. Women of reproductive age (Population) and with IBD (Exposure) were compared with healthy women of reproductive age (Comparison) to evaluate the ovarian reserve function (Outcome). Two reviewers searched three databases as well as relevant gray literature. After following the PRISMA 2020 guidelines, RevMan 5.0 software and Newcastle-Ottawa Scale (NOS) scoring were used to analyze and summarize the data included in the studies. The protocol was registered on PROSPERO (CRD42021267804)., Results: The search yielded 367 studies, out of which 13 were selected for full-text evaluation, and finally, seven studies were included in our research. An analysis of ovarian reserve function in IBD women of reproductive age and healthy women revealed that the ovarian reserve function was lower in IBD women of reproductive age than in healthy women (P < .01, I2 = 81%); the ovarian reserve function was significantly lower in women with IBD in remission than in healthy women (P < .01, I2 = 0%), and ovarian reserve function was lower in IBD women of reproductive age taking thalidomide than in healthy women (P < .01, I2 = 18%)., Conclusion: IBD could reduce ovarian reserve function in women of reproductive age, and patients should plan for conception as soon as possible under permissible conditions., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Castleman disease (CD) is a lymphoproliferative disorder with an unknown etiology. The disease may be unicentric (UCD) or multicentric (MCD), and three histopathologic variants have been described: hyaline vascular (HV), plasma cell (PC), and mixed type. Extranodal CD is rare. Herein, we report a case of CD presenting as a tonsillar mass, which has not been documented in the literature. Case presentation: The patient was a 32-year-old man. Laryngoscopy revealed tonsillar hypertrophy, and the patient underwent a low-temperature plasma tonsillectomy. Microscopic examination of permanent sections showed lymphoid follicular hyperplasia, a portion of which appeared to be a fusion of nodular hyperplasia (composed of lymphoid follicles of variable size and shape). These distinctive follicles with atrophic hyalinized germinal centers and a broad mantle zone of small lymphocytes formed concentric rings (so-called onion-skin arrangement). Medium-sized vessels and a plethora of capillaries were present in the center of the lymphatic follicles, mantle zones, and interfollicular areas. A characteristic lollipop appearance was also observed due to the onion-skin arrangement of the expanded mantle zone lymphocytes with a vessel penetrating the germinal center. No aberrant lymphoid population was present based on CD3, CD5, CD20, CD79α, CD21, CD23, bcl-2, cyclin D1, and ki-67 immunostaining. Tests for human herpesvirus (HHV)-8 and Epstein Barr virus (EBV)-encoded small RNA (EBER) were negative. Therefore, a diagnosis of an HV variant UCD was rendered. The patient was treated by local excision without any other therapy based on the diagnosis. At the 7-month follow up, the patient had no recurrent symptoms or masses. Conclusion: We present an unusual case of a tonsil presenting hyaline vascular Castleman disease (HVCD). This study aims to highlight CD as a differential diagnosis that should be considered by otolaryngologists and pathologists for lymphoproliferative disorders of the tonsil. [ABSTRACT FROM AUTHOR]

Trigeminal trophic syndrome (TTS) is a rare disease process that is thought to occur after insult to the trigeminal nerve. The earliest descriptions of this condition were provided in the early 20th century, yet it remains relatively unknown, with approximately 200 cases since described. Most commonly seen in older women, TTS characteristically involves persistent facial ulceration with loss of sensation and paresthesia along the distribution of the trigeminal dermatome. Ulceration often occurs in the alar region, following self‐manipulation in response to paresthesias. Time of onset of TTS after trigeminal insult may vary from weeks to decades, and emergence of ulceration may be associated with psychiatric disorders. Diagnosis is clinical and made by exclusion of similarly presenting conditions. Histology is nonspecific yet necessary to exclude other causes of facial ulceration. Although there is not yet a standard management strategy, a number of successful approaches have been reported including pharmaceutical and surgical interventions, installation of a protector, and transcutaneous nerve stimulation. However, because of the self‐inflicted manifestations of this disorder, behavioral modifications remain of the utmost importance. This review serves to address the history, epidemiology, pathogenesis, clinical presentation, histology, diagnosis, differential diagnosis, and management options for TTS. [ABSTRACT FROM AUTHOR]

Aims: Spindle cell/sclerosing rhabdomyosarcomas (SC/SRMS) feature spindled and/or rounded rhabdomyosarcomatous cells within variably hyalinised stroma. Only 30–67% of SC/SRMSs harbour neomorphic MYOD1 p.L122R mutations, indicating heterogeneity in this RMS type. We compared MYOD1‐mutant and non‐mutant cases to characterise the histological and genetic spectrum of mutated SC/SRMS. Methods and results: Seventeen RMSs with spindled, sclerosing or hybrid histology were sequenced to identify MYOD1 and PIK3CA mutations and reappraised to assess histological features and myogenic immunophenotypes. Twelve SC/SRMSs harboured MYOD1 mutations, including homozygous p.L122R (n = 8), heterozygous p.L122R (n = 3) and heterozygous p.E118K (n = 1). MYOD1‐mutant tumours affected nine females and three males aged 8–64 years (median = 22.5), had a median size of 4.2 cm (range = 2–22) and involved the head and neck (n = 7), extremities (n = 4) and mediastinum (n = 1). Fascicular/spindle histology was predominant in four cases, including one with heterologous lipoblasts in focally myxoid stroma. Four sclerosing cases mainly comprised rounded cells, including one with multinucleated tumour cells. Four cases were histologically hybrid. The only PIK3CA (p.H1047R) mutation was detected in a predominantly spindled MYOD1‐p.L122R‐mutated case, but not in its laser‐microdissected lipoblast‐containing area. All MYOD1‐mutant cases exhibited diffuse MYOD1 expression but patchy myogenin reactivity. At final follow‐up (median = 13.5 months), recurrences (n = 4), metastases (n = 2) or both (n = 1) occurred in seven MYOD1‐mutant cases; one had died of disease. Five non‐mutated cases were reclassified as spindle embryonal (n = 3), dense embryonal (n = 1) and unclassifiable (n = 1) RMSs. Conclusion: MYOD1‐mutant RMSs are uncommonly mutated with PIK3CA and behave aggressively with an expanded morphological and genetic spectrum, including lipoblastic differentiation, multinucleated cells and the alternative p.E118K mutation. [ABSTRACT FROM AUTHOR]

Sclerosing rhabdomyosarcoma (RMS) is a rare subtype of RMS with unique prominent stromal hyalinization and a pseudovascular architecture. It overlaps morphologically with spindle cell RMS and poses both diagnostic and therapeutic challenges because of its rarity and aggressive clinical course. In this article, we report a case of sclerosing RMS arising from a prior craniotomy site, which demonstrated both sclerosing and spindle cell components. A literature review of RMS with sclerosing morphology identified 122 cases. Our review documents the following: sclerosing RMS occurs in both childhood and adult populations, has a predilection for the head and neck areas, and has a worse prognosis in adults. Sclerosing RMS harbors a high frequency of MYOD1 mutations, conferring a poor clinical outcome. Sclerosing RMS and spindle RMS likely represent a morphologic spectrum of one entity. [ABSTRACT FROM AUTHOR]

A 70-year-old man with a history of bladder and colon cancer presented with an enlarging mass in his right lower extremity. Forty years before presentation, he had injured his right lower extremity in a motor vehicle accident. Imaging findings indicated suspected sarcoma, which led to biopsy. Biopsy and further surgical exploration revealed the presence of a surgical sponge and surrounding local inflammatory reaction. No neoplasm was found, and the sponge and involved tissues were removed. Gossypiboma is exceedingly rare in the extremities. Imaging of retained foreign material can appear suggestive of sarcoma because of strong inflammatory responses and local tissue mass-like derangement resulting in heterogeneous signal changes. Ultimately, biopsy must be performed to ensure that no oncological pathological condition is present. [ABSTRACT FROM AUTHOR]

Primary peritoneal carcinosarcoma is extremely rare and only few cases have been reported in the literature to date. We herein present a case of carcinosarcoma of the Douglas pouch in a 73-year-old Japanese woman. The patient complained of fever and lower abdominal pain, and a large pelvic mass (>10 cm in diameter) was detected, with rectal invasion. Laparotomy was performed and revealed a left ovarian abscess and a Douglas pouch mass; however, there was no obvious tumor involvement of the bilateral ovaries or uterus. The patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy and tumor debulking, with a reduction rate of ~30%. Sigmoid colostomy was also performed due to the deep and wide rectal invasion. Histologically, the tumor was composed of a mixture of ovarian high-grade serous carcinoma and spindle-cell sarcoma mimicking leiomyosarcoma. Immunohistochemically, the serous carcinoma component was positive for cytokeratin (CK)7, Wilms' tumor-1 and p53 (null type), while CDX-2 and CK20 were negative. The spindle-cell sarcoma component was positive for vimentin and α-smooth muscle actin. The present case was diagnosed as carcinosarcoma of the homologous type derived from the peritoneum in the Douglas pouch. The patient received several courses of combination chemotherapy with paclitaxel, carboplatin and bevacizumab, and achieved complete remission. The principal treatment for such cases is surgery, and several chemotherapeutic regimens, including paclitaxel and carboplatin, or cisplatin and ifosfamide, have been reported. The accumulation of more clinical cases is crucial for understanding the clinicopathological characteristics of these rare tumors and establishing effective therapeutic strategies. [ABSTRACT FROM AUTHOR]

Introduction. Plexiform schwannoma is a rare variant of schwannoma that accounts for only 5% of all schwannomas. Herein, we present a rare case of plexiform schwannoma of the tongue in a pediatric patient with neurofibromatosis type 2 (NF2). Case Presentation. A 13-year-old female presented with a growing left-sided tongue mass. The patient has a past medical history of NF2. The tongue mass was excised and histopathological examination revealed a spindle cell tumor with multinodular growth pattern, with Verocay bodies' formation. Tumor cells were strongly positive for S-100 protein and negative for smooth muscle actin (SMA), and EMA highlighted perineural fibroblasts surrounding tumor nodules. These findings were diagnostic of plexiform schwannoma. Conclusion. Plexiform schwannoma of the tongue is an extremely rare tumor seen in patients with NF2. Clinical examination and histopathological evaluation are important for diagnosis of plexiform schwannoma. [ABSTRACT FROM AUTHOR]

This is the case report of a 45-year-old woman affected by HIV, who was hospitalized for diffuse abdominal pain, constipation, and weight loss present for over one month. A colonoscopy showed the presence of a nontransitable stenosis of the ascending colon. A right hemicolectomy was performed. The histological examination reports CD with outbreaks of endometriosis. CD and the HIV infection may coexist in the same individual and it seems that HIV reduces the relapse rate in IBD patients. CD and intestinal endometriosis can also occur simultaneously. The diagnosis is often only made after surgical resection of the diseased segment. These patients were more likely to have stricturing CD but endometriosis does not seem to impact the natural history of CD. [ABSTRACT FROM AUTHOR]

Spindle cell/sclerosing rhabdomyosarcoma (ssRMS) is a new subtype of rhabdomyosarcoma included in theWorld Health Organization soft tissue and bone tumor classification in 2013. Despite the increasing number of reported cases of ssRMS, the imaging characteristics of ssRMS are not established. Herein, we present the case of an elderly Japanese woman with ssRMS of the masticator space with intracranial invasion without destruction of the adjacent bone. Attention should be paid to the presence of intracranial infiltration that may indicate a worse prognosis. Tumor growth without bone destruction could be a key finding to differentiate ssRMSs from conventional subtypes of rhabdomyosarcoma. [ABSTRACT FROM AUTHOR]

Dendritic cell sarcomas are rare tumours of antigen presenting cells. Data regarding their biology, management and outcomes are sparse. We analysed 66 patients with follicular dendritic cell sarcoma ( FDCS). Six patients also had Castleman disease, 9 had another malignancy and 13 had an autoimmune disease. Fifty-four per cent of patients presented with localized disease and 46% with systemic involvement. The median progression-free ( PFS) and overall survival ( OS) following frontline therapy was 21 and 50 months, respectively. Survival outcomes were significantly inferior in patients with extranodal, bulky or intra-abdominal disease at presentation. Stage was not associated with survival. Management approaches were heterogeneous. Patients who underwent an upfront gross total resection ( GTR) experienced better PFS and OS (both P < 0·0001). In patients who underwent a GTR, consolidative radiotherapy was associated with improved local control ( P = 0·03), PFS ( P = 0·04) and OS ( P = 0·05). In patients with measureable disease, gemcitabine with a taxane yielded an overall response rate of 80%. The pattern of relapse was predominantly locoregional. Salvage rates after recurrence were poor. Studies are underway at our institution to define the genomic profile in FDCS and identify potential novel therapeutic targets. [ABSTRACT FROM AUTHOR]