Case History
67 y/o male with B/L renal masses, found incidentally when undergoing lung cancer screening. Left mass measures 3.3 cm on gross section. Fumarate hydratase (FH) immunohistochemistry was done, and it was retained.
What is the diagnosis?
A. Cystic nephroma
B. Multiocular cystic renal neoplasm of low malignant potential
C. Tubulocystic renal cell carcinoma
D. Fumarate hydratase deficient renal cell carcinoma
Answer: C. Tubulocystic renal cell carcinoma
Discussion:
This is a case of a tubulocystic renal cell carcinoma. Histology reveals multiple cysts of small to intermediate size, and sometimes larger cysts, lined by a single layer of cuboidal to columnar epithelium that sometimes can be flattened or hobnailed. Cells have abundant eosinophilic cytoplasm with enlarged and irregular nuclei and prominent nucleoli. Stoma is fibrotic.
Tubulocystic renal cell carcinoma is a rare tumor, with male predominance, seen more between ages 50 to 60, with relatively indolent features. Usually it has a good prognosis, with rare reports of metastasis. Due to prominent nucleoli features, histological grading is not necessary.
In this case, fumarate hydratase (FH) immunohistochemistry was done to exclude fumarate hydratase deficient renal cell carcinoma, in which expression of FH is lost. In this case, FH expression is retained.
Case contributed by: Frances Gomez Gonzalez, M.D., GI/GU Pathology Fellow, UAB Pathology