[860] Clear Cell Renal Cell Carcinoma with Tubular-Follicular-Cystic Architecture.

Zuzana Kos, Eric C Belanger, Susan J Robertson, Bojana Djordjevic, Kien T Mai. The University of Ottawa, ON, Canada

Background: Clear cell renal cell carcinoma (CRCC) usually displays variable architecture, including alveoli, acini, tubules, follicles, cysts, papillae, solid nests and sheets. Large solid nests and sheets are usually associated with high nuclear grades, while areas with low Furhman nuclear grades (1-2/4) often display alveolar or tubulo-follicular-cystic (TFC) architecture, with or without papillae. We present an immunohistochemical and fluorescence in situ hybridization (FISH) study of CRCC with a predominant TFC architecture.
Design: 12 CRCC with TFC architectures were reviewed. Tumors with an alveolar architecture accounting for more than 10% of the tumor were excluded. Representative sections were submitted for immunostaining with cytokeratin 7 (CK7), alpha-methyl-acyl-CoA racemase (AMACR) and for FISH for loci 3p25 (Von Hippel Lindau gene) and 3p14 (fragile histidine triad gene), as well as for centromeres of chromosomes X, Y, 7 and 17.
Results: Male to female patient ratio was 5:1. Patient age ranged from 33-68 (54±8). All tumors were stage I and ranged in size from 1.2-3.5 cm (2.1±0.4). No recurrence or metastases occurred during the period of follow-up (up to 5 years with a mean of 3 years). Grossly, all tumors were encapsulated.
Focal areas of alveolar architecture were seen in 3 tumors. Focal areas with features of tubular cystic renal cell carcinoma with clear cell changes were identified in 4 tumors. Immunostaining showed positive CK7 reactivity ranging from diffuse in 7 tumors, focal in 3 tumors to negative in 2 tumors. AMACR reactivity was extensive in 2 and focal in the remaining 10 tumors.
FISH revealed 7 tumors with loss of 3p, 2 tumors with loss of 3p and gain of chromosome 7, and one tumor with loss of 3p and gain of chromosomes 7 and 17. The remaining 2 tumors showed no detectable chromosomal changes. Tumors without loss of 3p displayed strong and extensive CK7 reactivity. Tumors with trisomy 7/17 showed focal papillary formations.
Conclusions: We propose that CRCC with a TFC architecture is a distinct type of renal cell carcinoma (RCC), characterized grossly by encapsulation and microscopically by a predominant TFC architecture. The chromosomal findings suggest that these tumors do not always present with typical chromosomal changes of CRCC or papillary RCC.
Category: Genitourinary (including renal tumors)

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 94, Wednesday Morning


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