MALIGNANT-TUMORS OF THE KIDNEY, BRAIN, AND SOFT-TISSUES IN CHILDREN AND YOUNG-ADULTS WITH THE TUBEROUS SCLEROSIS COMPLEX

BACKGROUND. The tuberous sclerosis complex (TSC) is an autosomal domin ant disorder characterized by seizures, mental retardation, and benign tumors of the brain, heart, skin, and kidney. Malignant tumors also c an occur in patients with tuberous sclerosis, particularly in the kidn ey, although they occur less frequently than benign tumors. The types of malignancy that occur in TSC have not been characterized fully. MET HODS. Clinical and pathologic features of 8 malignant tumors from 6 TS C patients ranging in age from 22 months to 21 years are reviewed. Six tumors were renal, one was from the inguinal region, and one was from the brain. The tumors were analyzed for loss of heterozygosity (LOH) in the chromosomal regions of the TSC1, TSC2, and VHL genes. RESULTS. Three patients (ages 7, 8, and 20 years) had renal cell carcinomas (RC Cs). Two of these patients had multifocal RCCs. All three patients wit h RCC also had prominent multifocal dysplasia of renal cyst epithelium . Two patients (ages 20 and 21 years) had malignant angiomyolipomas (1 renal and 1 inguinal). One patient (age 22 months) had a Grade 4 gian t cell astrocytoma (glioblastoma multiforme). LOH in the region of the TSC2 gene was found, either in the malignant tumor or in benign tumor s, in all five patients whose DNA could be analyzed. CONCLUSIONS. Chil dren with TSC, as well as adults with the disease, are at risk for dev eloping malignant tumors. Two types of renal malignancy occur in TSC: RCC, which appears to arise from dysplastic renal cyst epithelial cell s, and malignant angiomyolipoma. Tumors cytologically similar to malig nant angiomyolipomas also may occur at extrarenal sites. LOH analyses suggest that the majority of patients with TSC who develop malignant t umors have germline TSC2, rather than TSC1, gene mutations. Cancer 199 8;83:2208-16. (C) 1998 American Cancer Society.