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Carney triad is a multitumor syndrome affecting almost exclusively young women in a nonfamilial setting, which manifests by multifocal gastric gastrointestinal stromal tumors, paragangliomas, and pulmonary chondroma. The Carney triad-associated tumors are characterized by a deficiency of the mitochondrial succinate dehydrogenase enzymatic complex. Recently, it has been observed that the deficiency results from epigenetic silencing of the SDHC gene by its promoter hypermethylation. To elucidate anatomic distribution of SDHC promoter methylation in Carney triad patients and thus to shed some light on the possible natural development of this epigenetic change, both neoplastic and available non-neoplastic tissues of 3 patients with Carney triad were tested for hypermethylation at the SDHC promoter site. SDHC promoter hypermethylation was proven in all tumors studied. Lack of SDHC epigenetic silencing in the non-neoplastic lymphoid and duodenal tissue (ie, tissues not involved in the development of Carney triad-associated tumors) together with the finding of SDHC promoter hypermethylation in the non-neoplastic gastric wall favors the hypothesis of postzygotic somatic mosaicism as the biological background of Carney triad; it also offers an explanation of the multifocality of gastrointestinal stromal tumors of the stomach occurring in this scenario as well. However, the precise mechanism responsible for the peculiar organ-specific distribution of Carney triad-associated tumors is still unknown., Competing Interests: The authors declare no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

High-grade prostatic adenocarcinoma mimicking urothelial carcinoma (UC) is a rare and unusual variant, which can present a difficult diagnostic challenge. The aim of this study was to examine telomerase reverse transcriptase (TERT) mutations in order to improve differential diagnostic process in this scenario. Ten prostatic adenocarcinomas mimicking UC were retrieved by searching in-house and consultation files of Charles University Hospital, Plzen, Czech Republic, Tenon Hospital Paris, France, and University of Calgary, Canada. We performed microscopic slide review and immunohistochemical and molecular-genetic analyses using the available paraffin tissue. Patient age at diagnosis ranged from 44 to 86 years (mean, 71.8 y). All cases were transurethral resections, except one which was a prostate biopsy. Gleason score 5+5 was observed in 6 patients, whereas the remaining 4 had a Gleason score of 4+5. The tumors showed pseudopapillary, solid, nested, and cribriform architectural growth patterns. All cases were positive for prostatic markers including PSA, PAP, and NKX3.1. Immunohistochemical staining for urothelial marker, GATA3, was negative in 6 cases and only weakly positive in the remaining 4. All 10 cases showed no evidence of TERT mutations. We describe 10 high-grade prostatic adenocarcinomas that on morphology mimicked UC, but all demonstrated negative TERT mutations. A finding of negative TERT mutations in high-grade prostatic adenocarcinoma which mimics UC supports the notion that TERT promoter mutations are absent in prostate carcinoma, which may also aid the diagnostic work-up in difficult cases.

We have studied a cohort of renal cell carcinomas (RCCs) with smooth-muscle stroma (N=6), which lacked any of following genetic aberrations: mutations in the VHL-gene-coding sequence, loss of heterozygosity of chromosome 3p, or hypermethylation of VHL. Using targeted next-generation sequencing, no intronic VHL mutations or mutations in selected genes involved in angiogenesis and genes frequently mutated in clear cell RCC were identified. Tumors were also tested for the presence of hotspot mutations in the TCEB1 gene with negative results in all cases. We conclude that there exists a group of RCCs with abundant leiomyomatous stroma, where the epithelial component is indistinguishable from conventional clear cell RCC and distinct from clear cell (tubulo-) papillary RCC and that these tumors lack aberrations related to the function of the VHL gene, mutations in genes involved in angiogenesis, and hotspot mutations in the TCEB1 gene.

Cystic nephroma (CN) and mixed epithelial stromal tumor (MEST) of the kidney have been considered as synonymous terms describing a single nosologic entity in adult patients. Cystic nephroma in pediatric patients (PCN) is, apparently, a completely different nosologic entity. Although the presence of DICER 1 mutations is well established in PCN, nothing is currently known about the DICER 1 gene status in adult MEST/CN. About 33 cases of MEST/CN were selected from the Plzen Tumor Registry; 4 cases were later excluded from the study due to low DNA quality. About 28 of the studied tumors displayed a benign morphology, whereas 1 was diagnosed as a malignant MEST/CN with sarcomatoid differentiation of the stromal component. All 29 samples analyzed using polymerase chain reaction and direct sequencing, including the case with the malignant morphology, were negative for mutation in DICER 1 hot-spot codons 1705, 1709, 1809, 1810, 1813, and 1814. Our results show that MEST/CN has no relation to PCN on a molecular genetic level. On the basis of our findings and the established morphologic differences between PCN and MEST/CN, we conclude that the term CN should be used for pediatric cases only and should be avoided in adult cases of MEST.