Case studySclerosing TFEB-rearrangement renal cell carcinoma: a recurring histologic pattern

- We report a TFEB renal cancer with dominant sclerosis, nearly obscuring the neoplasm.
- Immunohistochemistry revealed positivity for melanocytic and epithelial antigens.
- Fluorescence in situ hybridization confirmed TFEB and not TFE3 rearrangement.
- Predominant sclerosis may be a less common recurring pattern of TFEB carcinoma.

SummaryRenal cell carcinoma with TFEB rearrangement (t[6;11][p21;q13]) was initially recognized to be composed of dual populations of large cells with clear cytoplasm and small cells forming rosettes around hyaline material. With increasing awareness, however, the spectrum of described morphology has been found to be more heterogeneous. We report a 54-year-old woman who underwent partial nephrectomy for a 2.4-cm renal mass, composed of fibrosis, hyalinization, calcification, and ossification and a smaller component of epithelioid cells. Immunohistochemical staining revealed diffuse positivity for cytokeratin AE1/AE3 and PAX8, patchy labeling for melan-A, human melanosome, and cathepsin K, and negative caldesmon, smooth muscle actin, TFE3 protein, carbonic anhydrase IX, CD10, cytokeratin 7, epithelial membrane antigen, and inhibin. Fluorescence in situ hybridization confirmed rearrangement of TFEB and not TFE3. Together with one recent case in another report, our findings suggest that extensive sclerosis and ossification may be a less common recurring histology of TFEB-rearrangement renal cell carcinoma.