Massive renal adenomatosis: a case exhibiting low-grade malignancy.

A young man with gradually enlarging kidneys and radiographic findings strongly suggestive of polycystic disease was found on autopsy to have massive bilateral renal enlargement due to innumerable multifocal tumors, arising in atypical renal tubular epithelium, whose microscopic appearance ranged from that of so-called renal adenoma to that of low-grade renal cell carcinoma. Electron microscopy confirmed the epithelial nature of the neoplasms. Local lymph node metastases and pulmonary micrometastases were present. Death was due to renal insufficiency and to refractory hyperkalemia probably secondary to tumor necrosis. Only one similar case is reported in the recent literature.