A Case of Multilocular Cystic Nephroma: Clinical, Histological and Immunohistochemical Aspects

Multilocular cystic nephroma is uncommon tumor that supposedly lies at the benign end of the spectrum of adult cystic renal neoplasms. We present a 54-year-old female that underwent a left-sided nephrectomy following incidentally found on CT scan tumor renal mass. Grossly, the specimen from nephrectomy included renal parenchyma bearing tumor formation measuring 9 × 6 cm. The cut section was multiloculated, cystic. Microscopic examination demonstrated a cystic neoplasm with multiple variable-sized cysts lined by flattened to low cuboidal epithelium with dense regular nuclei and variable amount of cytoplasm with some degree of clearing. These cysts were separated by septae containing fibrocollagenous stroma enriched by smooth muscle bundles; occasional foci of calcification were encountered. The diagnosis of multilocular cystic nephroma was established and additional immunohistochemical (ICH) investigation with a panel of antibodies was performed (all provided by DAKO), adhering to the manufacturer’s instructions. The epithelial lining expressed both CKAE1-AE3 and CK19, was invariably positive for Vimentin and for unexplained reasons, showed weak to moderate expression of CD99. The stromal component consistently expressed SMA in fascicular fashion, while Desmin was expressed in a definitely patchy, dot-like manner. Epithelial cells did not express CD10 and CD15, lacked ER and PR. Similar negative profile was seen in the stromal cells within the septae. The same set of IHC markers was applied to the singular case of MCRCC we had. The only difference noted was weaker CK19 expression. We concluded that IHC is of little help when we are faced with distinguishing this neoplasm from the main diagnostic problem – multilocular cystic renal cell carcinoma.