RENAL MEDULLARY CARCINOMA - A POTENTIAL SICKLE-CELL NEPHROPATHY OF CHILDREN AND ADOLESCENTS

An extremely aggressive malignant epithelial neoplasm of the kidney ha s recently been described and named renal medullary carcinoma. The fin ding of this tumor is highly predictive of drepanocytes (sickle cells) in tissue sections and thus the presence of sickle hemoglobin, specif ically sickle cell trait, in the patient. We present a case report of this rare tumor in a 10-year-old male. The tumor displayed a variable histologic architecture including gland-like areas with intra- and ext racytoplasmic material resembling mucin with hematoxylin and eosin sta in. This material was negative with periodic acid-Schiff and mucicarmi ne stains, stained only weakly with Alcian Blue, and was positive usin g antibodies against peanut agglutinin. Tumor cells stained positively with antibodies to epithelial membrane antigen, cytokeratin, vimentin , and Ulex europaeus lectin. The luminal face of tumor cells stained w ith peanut agglutinin. Stains using antibodies against carcinoembryoni c antigen and alpha-fetoprotein were negative. Ultrastructurally, the tumor cells were characterized by short microvilli lining the luminal surface and lateral complex infoldings of adjacent plasma membranes. W e discuss the relationship of this neoplasm to another renal pelvic ne oplasm, collecting duct carcinoma, which may rarely occur in children. Renal medullary carcinoma should be included in the differential diag nosis of gross hematuria, which is most commonly benign self-limited h ematuria, in young patients with sickle cell trait.