Chromophobe renal cell carcinoma with osseous metaplasia containing fatty bone marrow element: a case report.

A 27-year-old woman presenting with epigastric pain and dyspepsia was found to have a calcified mass in the upper-middle right kidney. Gross examination of the nephrectomy specimen revealed a 6.5 x 5 x 4 cm renal tumor with dense calcification and ossification. Histopathological examination of the tumor showed solid, trabecular sheets and nesting of polygonal epithelial cells with abundant cytoplasm and prominent cell border and mature bony tissue enclosing fatty marrow. Renal cell carcinoma is frequently associated with calcification, but ossification is extremely rare. To our knowledge, we report the fourth case of a chromophobe renal cell carcinoma with extensive calcification and ossification.