Collecting Duct Carcinoma Exhibiting Diastase-Resistant PAS-Positive Globular Cytoplasmic Inclusions and Rhabdoid Features Arising in Adult Polycystic Kidney Disease: A Case Report

A 76-year-old man complained of lumbago, and a subsequent detailed examination revealed a mass in the left kidney. Macroscopically, multiple cysts were recognized in the bilateral kidney; the tumor proliferated predominantly in the renal medulla and showed a whitish color with focal necrosis and hemorrhage. A histologic examination of the surgically resected tumor showed various growth patterns, such as solid, tubular, and papillary, by tumor cells. The diagnosis of collecting duct carcinoma (CDC) was made. Furthermore, tumor cells contained globular inclusions resembling hyaline globules and large eosinophilic inclusions, resulting in rhabdoid features, in the cytoplasm. Histochemically, globular inclusions were positive for periodic acid-Schiff (PAS) with diastase pretreatment. Immunohistochemically, large esosinophilic inclusions were reactive for vimentin. Although these findings are rare in CDCs, they should be recognized in the pathologic spectrum of CDCs.