Diagnosis: Renal cell carcinoma associated with hereditary leiomyomatosis.

Comment: This hereditary syndrome is autosomal dominant with stigmata of cutaneous leiomyomas or uterine fibroids in women. There is a mutation in a tumor suppressor gene that encodes fumarate hydratase, which is involved in tricarboxylic acid cycle (Kreb's cycle). The renal tumors show cells with eosinophilic cytoplasm and a finding that is considered characteristic of this tumor: prominent eosinophilic nucleoli with perinucleolar clearing (Figs. 4 and 5).