Department of Pathology, Johns Hopkins University, Baltimore, Maryland 21231-2410, USA.
Urology. 2011 Aug;78(2):474.e1-5. doi: 10.1016/j.urology.2011.04.043. Epub 2011 Jun 25.
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.
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.
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.
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.
集合管癌（CDC）是一种罕见且侵袭性的肾肿瘤，倾向于累及肾窦。CDC 表现出多种形态学特征，这些特征可能与肾髓质癌重叠。最初在中枢神经系统、肾脏和软组织的儿科恶性横纹肌样肿瘤中发现的 SMARCB1/INI1 肿瘤抑制基因的缺失，最近也在肾髓质癌中被描述。本研究通过免疫组织化学评估了一系列 CDC 中 SMARCB1/INI1 的表达情况。
使用 20 例 CDC 存档病例构建组织微阵列。每个肿瘤点 3-7 次；如有可能，还包括同一标本的良性组织。使用针对 SMARCB1/INI1 基因产物的单克隆小鼠抗体 BAF47 评估 SMARCB1/INI1 的免疫表达。核染色被认为是 SMARCB1/INI1 表达的指标。
在 20 例 CDC 中，有 3 例完全丧失 SMARCB1/INI1 表达，另有 3 例显示局灶性和弱阳性染色。其余肿瘤表现为多灶性或弥漫性 SMARCB1/INI1 表达，染色强度不同。SMARCB1/INI1 状态与临床病理和结局特征之间无显著差异。
在 15%的 CDC 中发现完全丧失 SMARCB1/INI1 免疫表达。SMARCB1/INI1 阳性和阴性病例在临床病理和结局特征方面无差异。我们的结果表明，一些 CDC 病例可能与涉及 SMARCB1/INI1 基因的遗传改变有关。此外，SMARCB1/INI1 免疫表达在 CDC 与肾髓质癌的鉴别诊断中似乎价值有限，尽管这些结果需要进一步验证。
