Ano de Publicação: 2011
AUTORIA
Hillary Elwood, Alcides Chaux, Luciana Schultz, Peter B. Illei, Dilek E. Baydar,
Athanase Billis, Rajni Sharma, Pedram Argani, Jonathan I. Epstein, and George J. Netto
RESUMO
OBJECTIVES Collecting duct carcinoma (CDC) is a rare and aggressive renal tumor with a tendency to
involve the renal sinus. CDC displays variable morphologic features that can overlap with those
of renal medullary carcinoma. The loss of SMARCB1/INI1 tumor suppressor gene, initially found
in pediatric malignant rhabdoid tumors of the central nervous system, kidneys, and soft tissues,
was also recently described in renal medullary carcinoma. The current immunohistochemical
study assessed SMARCB1/INI1 expression in a series of CDCs.
METHODS A total of 20 archival cases of CDC were used to construct a tissue microarray. Each tumor was
spotted 3-7 times; benign tissue from the same specimen was also included when available. The
immunoexpression of SMARCB1/INI1 was evaluated using BAF47, a monoclonal mouse antibody
directed against the SMARCB1/INI1 gene product. Nuclear staining was considered as
indicative of SMARCB1/INI1 expression.
RESULTS The complete loss of SMARCB1/INI1 expression was observed in 3 of 20 cases of CDC. Another 3
cases revealed focal and weak intensity staining. The remaining tumors showed multifocal or diffuse
SMARCB1/INI1 expression with variable staining intensity. No significant differences were found in
the clinicopathologic and outcome features regarding SMARCB1/INI1 status.
CONCLUSIONS The complete loss of SMARCB1/INI1 immunoexpression was found in 15% of CDC. No
differences were found between the SMARCB1/INI1 positive and negative cases regarding the
clinicopathologic and outcome features. Our results suggest that some CDC cases might be
associated with genetic alterations involving the SMARCB1/INI1 gene. In addition, SMARCB1/
INI1 immunoexpression seems to be of limited value in the differential diagnosis of CDC versus
renal medullary carcinoma, although these results require additional validation. UROLOGY 78:
474.e1– 474.e5, 2011. © 2011 Elsevier Inc.