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The rapidly evolving stem cell field puts much stress on developing educational resources. The ISSCR Education Committee has created a flexible stem cell syllabus rooted in core concepts to facilitate stem cell literacy. The free syllabus will be updated regularly to maintain accuracy and relevance.

Aims: Superficial CD34‐positive fibroblastic tumour (SCD34FT) is an uncommon but distinctive low‐grade neoplasm of the skin and subcutis that shows frequent CADM3 expression by immunohistochemistry (IHC). In this study, prompted by an index case resembling 'atypical fibrous histiocytoma (FH)' that was positive for CADM3 IHC, we systematically examined a cohort of tumours previously diagnosed as 'atypical FH' by applying CADM3 and fluorescence in situ hybridization (FISH) for PRDM10 rearrangement, to investigate the overlap between these tumour types. Methods and Results: Forty cases of atypical FH were retrieved, including CD34‐positive tumours (n = 20) and CD34‐negative tumours (n = 20). All tumours were stained for CADM3. All CADM3‐positive tumours were evaluated by FISH to assess for PRDM10 rearrangement. Eleven CD34‐positive tumours (11/20, 55%) coexpressed CADM3 and were reclassified as SCD34FT. None (0/20) of the CD34‐negative atypical FH were CADM3‐positive. Reclassified SCD34FT (10/11) arose on the lower extremity, with frequent involvement of the thigh (n = 8). Features suggestive of atypical FH were observed in many reclassified cases including variable cellularity, spindled morphology, infiltrative tumour margins, collagen entrapment, epidermal hyperpigmentation, and acanthosis. Variably prominent multinucleate giant cells, including Touton‐like forms, were also present. An informative FISH result was obtained in 10/11 reclassified tumours, with 60% (6/10) demonstrating PRDM10 rearrangement. Conclusion: A significant subset of tumours that histologically resemble atypical FH, and are positive for CD34, coexpress CADM3 and harbour PRDM10 rearrangement, supporting their reclassification as SCD34FT. Awareness of this morphologic overlap and the application of CADM3 IHC can aid the distinction between SCD34FT and atypical FH. [ABSTRACT FROM AUTHOR]

Background Even though cytoreductive nephrectomy (CN) was once the standard of care for patients with advanced renal cell carcinoma (RCC), its role in treatment has not been well analyzed or defined in the era of immunotherapy (IO). Materials and Methods This study analyzed pathological outcomes in patients with advanced or metastatic RCC who received IO prior to CN. This was a multi-institutional, retrospective study of patients with advanced or metastatic RCC. Patients were required to receive IO monotherapy or combination therapy prior to radical or partial CN. The primary endpoint assessed surgical pathologic outcomes, including American Joint Committee on Cancer (AJCC) staging and frequency of downstaging, at the time of surgery. Pathologic outcomes were correlated to clinical variables using a Wald-chi squared test from Cox regression in a multi-variable analysis. Secondary outcomes included objective response rate (ORR) defined by response evaluation criteria in solid tumors (RECIST) version 1.1 and progression-free survival (PFS), which were estimated using the Kaplan-Meier method with reported 95% CIs. Results Fifty-two patients from 9 sites were included. Most patients were male (65%), 81% had clear cell histology, 11% had sarcomatoid differentiation. Overall, 44% of patients experienced pathologic downstaging, and 13% had a complete pathologic response. The ORR immediately prior to nephrectomy was stable disease in 29% of patients, partial response in 63%, progressive disease in 4%, and 4% unknown. Median follow-up for the entire cohort was 25.3 months and median PFS was 3.5 years (95% CI, 2.1-4.9). Conclusions IO-based interventions prior to CN in patients with advanced or metastatic RCC demonstrates efficacy, with a small fraction of patients showing a complete response. Additional prospective studies are warranted to investigate the role of CN in the modern IO-era. [ABSTRACT FROM AUTHOR]

Aims: Classification of renal neoplasms on small tissue biopsies is in increasing demand, and maintaining broad differential diagnostic considerations in this setting is necessary. When evaluating a renal or perirenal tumour biopsy with sarcomatoid morphology, together with sarcomatoid renal cell carcinoma and sarcomatoid urothelial carcinoma as top diagnostic considerations, it is vital to additionally consider the possibility of well‐differentiated and de‐differentiated liposarcoma. Methods and results: This study reports a series of 30 biopsy samples from sites in or around the kidney collected from four institutions in which the correct diagnosis was either well‐differentiated or de‐differentiated liposarcoma. The majority (26 of 30, 87%) of lesions were accurately diagnosed on biopsy sampling, all of which incorporated testing for MDM2 by immunohistochemistry (IHC), fluorescence in‐situ hybridisation (FISH) or a combination of the two as part of the diagnostic work‐up. Tumour expression of MDM2 by IHC without confirmatory FISH analysis was sometimes (30%) sufficient to reach a diagnosis, but demonstration of MDM2 amplification by FISH was ascertained in the majority (57%) of biopsy samples. A diagnosis of de‐differentiated liposarcoma was not definitively established until resection in four (13%) patients, as no MDM2 testing was performed on the corresponding pre‐operative biopsies. Conclusions: When a retroperitoneal tumour is not clinically suspected, histological consideration of a liposarcoma diagnosis may be overlooked. Implementation of ancillary immunohistochemical and cytogenetic testing can ultimately lead to a definitive diagnosis in this potentially misleading anatomical location. [ABSTRACT FROM AUTHOR]

Spermatocytic tumor (ST) is a rare type of germ cell tumor that occurs exclusively in the postpubertal testis and typically affects elderly men. Most STs are benign, but rare cases exhibit aggressive clinical behavior, often in association with transition to sarcomatoid histology. Limited molecular analyses have been performed on STs; therefore, their genomic and epigenomic features remain incompletely described. Twenty‐seven samples from 25 individual patients were analyzed with a combination of DNA sequencing panels, genomic methylation profiling, SNP array, isochromosome (12p) [i(12p)] FISH, and immunohistochemistry. The series included five metastasizing tumors (three with sarcomatoid transformation, one anaplastic, and one conventional) and 20 non‐metastasizing tumors (14 anaplastic and six conventional). Anaplastic tumors comprised a monomorphic population of intermediate‐sized neoplastic cells, as previously described. Multiomic analyses demonstrated that there were two genomic subgroups of STs: one with diploid genomes and hotspot RAS/RAF variants and the other with global ploidy shift and absence of recurrent mutations. Relative gain of chromosome 9 was a consistent finding in both subgroups. A comparison of metastasizing and non‐metastasizing cases demonstrated that aggressive behavior was associated with the acquisition of pathogenic TP53 mutations and/or relative gains of 12p/i(12p). In cases with sarcomatoid transformation, TP53 mutations seem to underlie the transition to sarcomatoid histology. Genomic methylation analysis demonstrated that aggressive cases with gains of 12p cluster closer to pure seminomas than to STs without gains of 12p. In conclusion, STs include two genomic subgroups, characterized by global ploidy shifts without recurrent mutations and diploid genomes with RAS/RAF hotspot mutations, respectively. Biologic progression was associated with relative gains of 12p and TP53 mutations. The findings in STs with relative gains of 12p suggest that they may exhibit biologic characteristics akin to those seen in germ cell neoplasia in situ‐related germ cell tumors rather than non‐germ cell neoplasia in situ‐derived STs. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Author(s): Philip M. Short[sup.1] , William J. Anderson[sup.1] , Douglas H. J. Elder[sup.2] , Allan D. Struthers[sup.3] , Brian J. Lipworth[sup.1] Author Affiliations: (1) Scottish Centre for Respiratory Research, Cardiovascular [...], Purpose Left ventricular hypertrophy (LVH) is a significant cardiac risk factor, associated with increased mortality. The impact of LVH on mortality in chronic obstructive pulmonary disease (COPD) is unknown. We evaluated the impact of LVH on mortality in COPD patients by measurement of left ventricular dimensions by echocardiography. Methods Retrospective cohort study utilizing a NHS database of COPD patients (TARDIS), in Tayside, Scotland (2001-2010), linked with databases regarding echocardiograms, pharmacy prescription, and the General Register Office for Scotland death registry. Cox proportional hazard regression was used to determine hazard ratios for mortality and hospital admissions based upon left ventricular mass index (LVMI) and left ventricular internal diastolic diameter after correction for all available influential covariates. Increased LVIDd was defined as >5.3 cm (female) and >5.9 cm (male). LVH was defined as an LVMI of >95 g/m.sup.2 (female) and >115 g/m.sup.2 (male). Results 617 patients were included for analysis. Mean (SD) age at diagnosis, 70 (9); mean FEV.sub.1 % (SD), 60.6 (19.3); mean resting SaO.sub.2 % (SD), 92.7 (10). Mean follow-up 4.5 years. Increased LVIDd was not associated with increased mortality, [chi].sup.2= 0.767, p = 0.381. Increased LVMI was associated with a significant increased risk of mortality, [chi].sup.2 = 5.447, p = 0.02 with an adjusted HR (95 % CI) of 1.542 (1.068-2.228), p = 0.021. Conclusions The presence of LVH, demonstrated by elevated left ventricular mass index is associated with a significantly increased risk of mortality in COPD patients. Therapeutic interventions are required to address this important modifiable risk factor in COPD patients.