Renal translocation carcinoma with expression of TFEB: presentation of a case with distinctive histological and immunohistochemical features.

The authors describe a case of renal cell carcinoma with t(6; 11) (p21; q12) in a 22-year-old man. The tumor showed typical histological features of this neoplasm with 2 types of cells and hyaline nodules surrounded by small cells. Characteristically, the tumor showed cystic lumina with hyaline-papillary structures inside and in some areas large and irregular intratumoral vessels. On immunohistochemical study, the tumoral cells were positive for melanocytic markers and transcription factor EB, as also for AE1-AE3 and Cam5.2 anticytokeratin antibodies. The expression of epithelial markers in this neoplasm is uncommon, and we think it is an important finding because otherwise, if melanocytic markers such as HMB45 or Melan A are not used, some renal cell carcinomas with the t(6; 11) (p21; q12) may be mistaken for other more common renal cell carcinomas.

Combined Papillated Bowen Disease and Clear Cell Atypical Fibroxanthoma.

We describe a case of papillated Bowen disease (PBD), associated with a clear cell atypical fibroxanthoma (CCAFXA). The epidermal lesion showed a bowenoid papillomatous growth pattern with histologic features suggestive of infection by human papilloma virus (HPV). In the dermis a neoplasm made up by spindled or polygonal cells with wide clear cytoplasm and moderate nuclear pleomorphism was found. Immunohistochemical characteristics of these two lesions were clearly different. The atypical cells of the intraepidermal proliferation were positive for AE1-AE3 anticytokeratin antibody, EMA, p16, p53 and p63. The dermal tumor was positive for vimentin, CD10, CD68, CD99, alpha-1-antitrypsin and c-kit. Histological features and immunohistochemical profile of the dermal tumor corresponded to a CCAFXA, a very uncommon neoplasm of which only 10 cases have been reported. In situ hybridization for numerous types of HPVs was negative in both lesions.