阴茎肌性内膜瘤临床病理观察

Penile myointimoma: a clinicopathologic study

目的探讨阴茎肌性内膜瘤的临床病理学特征、免疫表型、鉴别诊断及预后。方法对1例阴茎肌性内膜瘤的临床资料、病理特点及免疫组化标记进行研究并复习相关文献。结果患者男性,13岁。阴茎龟头部结节状肿物1个月。肿瘤大小0.8 cm×0.5 cm×0.5 cm,组织学表现为尿道海绵体原有的血管腔肌内膜细胞肿瘤性增生,形成多结节状或丛状结构。瘤细胞呈梭形或星状,平行排列成束或杂乱排列,包埋于黏液样间质中;细胞有长锥形或纤维状嗜酸性胞质突起,核呈梭形或卵圆形,无明显异型性,未见核分裂象。病变血管腔内瘤细胞增生而使管腔闭塞或残留狭窄的新月形腔隙,血管壁固有的平滑肌常包绕瘤结节。免疫组化示瘤细胞vimentin、SMA、actin和calponin(+);S100、CD34、CD31、CD68、CK、EMA和desmin(-);残留的血管壁平滑肌强(+),呈衣领状包绕瘤结节;Ki-67阳性指数<1%。结论阴茎肌性内膜瘤是一种罕见的、起源于阴茎尿道海绵体血管内膜细胞的良性间叶性肿瘤。认识它的重要意义在于与形态类似的侵袭性肿瘤相鉴别。

Objective To evaluate the clinicopathological features,immune phenotype,differential diagnosis and prognosis of penile myointimoma. Methods A case of penile myointimoma was analyzed by clinicopathological observation,immunohistochemistry and literature review. Results A male patient of 13-year-old presented with a 1month history of a nodular mass involving the glans penis and the size of the tumor was 0. 8 cm × 0. 5 cm × 0. 5 cm.Histologic examination revealed occlusive myointimal proliferation with a complex multinodular/plexiform architecture involving the preexisting vasculature of the corpus spongiosum. The neoplasm was composed of sheets of spindled and stellate-shaped cells with long tapered or fibriform eosinophilic cytoplasmic processes embedded in fibromyxoid matrix. No significant nuclear atypia was present,and no mitotic figures were identified. The native smooth muscle of the vascular walls surrounded the lesion and some vascular lumens were still visible. Immunohistochemical staining showed that the myointimal cells were positive for vimentin,SMA,actin and calponin but negative for S100,CD34,CD31,CD68,CK and EMA. Desmin showed negative in the lesional cells,but highlighted the native residual smooth muscle cells in the vascular walls confirming the intravascular proliferation. In addition,the Ki67 positive rate was less than 1%. Conclusion Penile myointimoma is a rare,benign mesenchymal tumor derived from the intimal cells of blood vessels in the corpus spongiosum of the penis. The main importance of recognizing myointimoma is to distinguish it from more clinically aggressive histologic mimic neoplasms.