Tubulocystic Carcinoma of the Kidney

Abstract

A distinctive tumor described under the terms Bellini duct carcinoma and low-grade collecting duct carcinoma has been referred to by us and others as tubulocystic carcinoma. This renal cell carcinoma subtype is not recognized in the World Health Organization 2004 classification. Herein, we present a detailed study of 31 cases to further characterize this rare subtype of renal cell carcinoma. The tumor occurred in adults (mean age, 54 years) with a strong male predominance (7:1). Grossly, the tumors ranged from 0.7 to 17 cm, and exhibited a spongy or "bubble wrap" appearance reflecting the microscopic presence of variably sized cystically dilated tubules lined by a single layer of epithelium. The lining varied with a cuboidal, flat, and hobnail cell appearance, and the neoplastic cells had abundant eosinophilic cytoplasm and enlarged nuclei with prominent nucleoli. The cysts were closely spaced with an intervening variably fibrotic stroma. Immunohistochemistry and ultrastructural examination showed features of proximal convoluted tubules (Pax 2 immunoreactivity and short microvilli with brush border organization) and distal nephron (kidney-specific cadherin immunoreactivity and cytoplasmic interdigitation). Gene expression profiling showed that tubulocystic carcinoma displayed a unique molecular signature. Twenty-four tumors were stage pT1, 4 stage pT2, and 3 stage pT3. Disease progression (median follow-up of 56 months) occurred in 3 patients; 1 with local recurrence, and 2 with distant metastasis to bone and liver. In light of the distinctive clinicopathologic features and a low but definite metastatic potential, this unique subtype of renal cell carcinoma deserves formal recognition in the contemporary classification of renal neoplasms.

Tubulocystic renal cell carcinoma: Report of a rare case

“…1 TC-RCC is a tumour of adulthood, with a mean age of 60 years and a strong male preponderance. [1][2][3] Patients are often asymptomatic, which has been attributed to the small size of these tumours (usually <2 cm). Patients harbouring larger tumours may, however, present with abdominal pain, distension, or even hematuria.…”

“…5 Solid areas, small foci of clear cell change or papillary configuration are rare, and may herald aggressive behaviour and worsen clinical outcome. 2,6,7 However, more recent data have suggested that TC-RCCs with focal dedifferentiation (TC-D-RCC) may actually represent hereditary leiomyomatosis RCC syndrome -associated RCC (HLRCC), as some TC-D-RCC cases show loss of fumarate hydratase immunoexpression and S-(2-Succino)-Cysteine (2SC) immunopositivity, similar to HLRCC (Table 1). 8 The histogenesis of TC-RCC remains unclear.…”

“…9 Ultrastructurally, they display cells with abundant microvilli, with a brush border appearance resembling PCT, along with cells with complex cytoplasmic interdigitations reminiscent of intercalated cells of collect- tubulocystic renal cell carcinoma ing ducts. 2,9 The presence of features of both proximal and distal nephron led Brennan and colleagues to hypothesize an origin from renal tubule stem cells. 10 As gene expression profiling and detection of molecular alterations (gains in chromosomes 7 and 17, loss of chromosome Y) are similar to papillary RCC (PRCC), a relationship between TC-RCC and PRCC has been proposed.…”

“…1 However, local recurrences, as well as metastases to lymph nodes, liver, bone and brain have been described. [2][3][4][5][6][7]13 One cannot at present be certain of the outcome, especially in unusual cases where there is focal clear cell, papillary or sarcomatoid change.…”

Genome-wide methylation analysis of tubulocystic and papillary renal cell carcinomas

“…Mostly, such tumors are composed of tubules and cysts lined by a single layer of typical hobnail cells with large nuclei and prominent nucleoli. The literature describing biological behavior, immunohistochemical profiles, ultrastructural features and possible differential diagnostic features of TRCC is limited [2][3][4][5][6]. The oncogenesis of this neoplasm is unclear.…”