Renal Cell Carcinoma in Tuberous Sclerosis Complex

Abstract

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder in which renal manifestations are prominent. There are three major renal lesions in TSC: angiomyolipomas, cysts, and renal cell carcinoma (RCC). Major recent advances have revolutionized our understanding of TSC-associated RCC, including two series that together include more than 100 TSC-RCC cases, demonstrating a mean age at onset of about 36 years, tumors in children as young as 7, and a striking 2:1 female predominance. These series also provide the first detailed understanding of the pathologic features of these distinctive tumors, which include chromophobe-like features and eosinophilia, with some of the tumors unclassified. This pathologic heterogeneity is distinctive and reminiscent of the pathologic heterogeneity in Birt-Hogg-Dube-associated RCC, which also includes chromophobe-like tumors. Additional advances include the identification of sporadic counterpart tumors that carry somatic TSC1/TSC2/mTOR mutations. These include unclassified eosinophilic tumors, eosinophilic solid cystic RCC (ESC-RCC), and RCC with leiomyomatous stroma (RCCLMS). A variety of epithelial renal neoplasms have been identified both in patients with tuberous sclerosis complex (TSC) and in the nonsyndromic setting associated with somatic mutations in the TSC1 and TSC2 genes. Interestingly, whether tumors are related to a germline or somatic TSC1/2 mutation, these tumors often display similar morphologic and immunophenotypic features. Finally, recent work has identified molecular links between TSC and BHD-associated tumors, involving the TFEB/TFE3 transcription factors.

Keywords: RCC with leiomyomatous stroma; TSC1; TSC2; chromophobe RCC; eosinophilic solid cystic RCC; hybrid oncocytic chromophobe tumor; renal cell carcinoma; tuberous sclerosis complex.

Figure 1

TSC-associated papillary RCC. (A–D) Low- and high-power views showing tumor cells with voluminous clear cytoplasm and complex branching architecture encapsulated by a prominent fibromuscular stroma (H&E 20×, 100×, 400×, 200×).

Figure 2

Hybrid oncocytic/chromophobe tumor (HOCT). (A–C) Low- and high-power views showing polygonal tumor cells with abundant eosinophilic cytoplasm and round centrally located nuclei resembling an oncocytoma but with perinuclear halos or clearing, seen in ChRCC (H&E 20×, 100×, 400×), and (D) characteristic positivity for CD117 (100×).

Figure 3

Eosinophilic solid and cystic RCC (ESC-RCC). (A–C) Low- and high-power views showing a solid and cystic tumor with granular eosinophilic cytoplasm, round nuclei, and prominent nucleoli (H&E 40×, 100×, 200×). (D) Tumor cells typically display CK20 positivity (100×).