Novel molecular aberrations and pathologic findings in a tubulocystic variant of renal cell carcinoma.

Tubulocystic renal cell carcinoma (TRCC) is an indolent type of renal cell carcinoma with a good prognosis based on the limited number of published cases. Herein, we describe the unusual clinical, pathologic and molecular findings in a case of TRCC. Our patient with TRCC had two local recurrences and a brain metastasis following radical nephrectomy. Unusual histologic findings included focal solid growth pattern and cytologic atypia. A genome-wide molecular inversion probe assay identified copy number (CN) loss in three chromosome regions and one region with copy-neutral loss of heterozygosity (copy-neutral LOH). Copy number variations (CNVs) were observed (chromosomes 4p16.1 and 17q21.31-q21.32) in both the tumor and the normal tissue, and most likely represents benign variations. The loss of entire chromosomes 9, 18 and 15 and copy-neutral LOH involving 6p22.1 was observed only in the tumor. The presence of these clinical, pathologic and molecular findings could be related to an increased risk for tumor recurrence and poor prognosis. The novel molecular findings described in TRCC might represent new targets for novel therapies.