Department of Anatomic Pathology, Glickman Urological and Kidney Institute, Taussig Cancer Institute, and Genomic Medicine Institute, The Cleveland Clinic, Cleveland, OH 44195, USA.
Hum Pathol. 2011 Nov;42(11):1770-6. doi: 10.1016/j.humpath.2011.02.022.
Smoothelin, a marker of differentiated smooth muscle, is diffusely expressed by bladder muscularis propria and is negative to only weakly and focally expressed in muscularis mucosae. We used bladder diverticula, which lack muscularis propria and frequently demonstrate hyperplastic muscularis mucosae, to evaluate the use of smoothelin immunoreactivity in diagnostic pathology. Diverticula from 40 patients (21 with benign features, 19 with neoplastic features) were studied. Immunohistochemistry was performed using smoothelin antibody (clone R4A, 1:150 dilution; Abcam, Cambridge, MA); and tissue was scored as 0 (no expression), 1+ (moderate expression b10% of cells), 2+ expression (moderate expression N10% of cells), and 3+ (robust diffuse expression). All diverticula contained muscularis mucosae of varying caliber; staining in diverticular muscularis mucosae was compared with historic results in the muscularis mucosae of cystectomy specimens. Hyperplastic muscularis mucosae occurred in 31 (78%) of 40 cases. Smoothelin immunoreactivity in the diverticular muscularis mucosae included 0 (16/40, or 40%); 1+ (11/40, or 27.5%); 2+ (13/40, or 32.5%); and 3+ (0/40, or 0%), with a slightly higher 2+ expression level in hyperplastic versus nonhyperplastic muscularis mucosae (35% versus 22%). Adjacent normal muscularis propria, present in 12 specimens, demonstrated 3+ muscularis propria immunoreactivity. Comparison between diverticula with benign and neoplastic features showed no significant difference in smoothelin immunoreactivity. No correlation was evident with smoothelin immunohistochemistry and muscle caliber. Smoothelin immunoreactivity in bladder diverticula confirms the limited nature of smoothelin expression in the muscularis mucosae and represents a useful ancillary technique in the proper histopathologic evaluation of diverticular and nondiverticular bladder carcinomas. A strong and robust staining of smooth, rounded muscle with smoothelin remains a useful diagnostic adjunct in the reliable recognition of muscularis propria.
平滑肌调宁蛋白是一种分化型平滑肌标志物，在膀胱固有肌层呈弥漫性表达，而在黏膜肌层仅呈弱阳性和局灶性表达。我们使用缺乏固有肌层且常表现为黏膜肌层增生的膀胱憩室来评估平滑肌调宁蛋白免疫反应在诊断病理学中的应用。研究了 40 例患者（21 例良性特征，19 例恶性特征）的憩室。使用平滑肌调宁蛋白抗体（克隆 R4A，1:150 稀释；Abcam，剑桥，MA）进行免疫组织化学染色；组织评分 0 分（无表达）、1+分（中度表达 b10%的细胞）、2+分（中度表达 N10%的细胞）和 3+分（强弥漫性表达）。所有憩室均包含不同大小的黏膜肌层；将憩室黏膜肌层的染色与膀胱部分切除术标本黏膜肌层的历史结果进行比较。40 例中有 31 例（78%）存在黏膜肌层增生。憩室黏膜肌层中的平滑肌调宁蛋白免疫反应包括 0 分（40 例中的 16 例，40%）、1+分（40 例中的 11 例，27.5%）、2+分（40 例中的 13 例，32.5%）和 3+分（40 例中的 0 例，0%），增生性黏膜肌层的 2+表达水平略高于非增生性黏膜肌层（35%比 22%）。12 例标本中存在邻近的正常固有肌层，表现为 3+固有肌层免疫反应。良性和恶性特征的憩室之间的平滑肌调宁蛋白免疫反应无显著差异。平滑肌调宁蛋白免疫组织化学与肌层直径之间无明显相关性。膀胱憩室中的平滑肌调宁蛋白免疫反应证实了平滑肌调宁蛋白在黏膜肌层中的表达具有局限性，是憩室和非憩室膀胱癌正确组织病理学评估的有用辅助技术。平滑肌调宁蛋白对圆形平滑肌的强而强染色仍然是可靠识别固有肌层的有用诊断辅助手段。
