富含黑色素的胰腺血管周上皮样细胞肿瘤1例临床病理观察

Melanin-rich pancreatic PEComa:a case report and review of literature

目的探讨1例伴显著黑色素的胰腺血管周上皮样细胞肿瘤(PEComa)的临床病理学特征、诊断与鉴别诊断。方法回顾性分析1例罕见的胰腺PEComa,结合光镜、免疫组化及特殊染色进行观察,并复习相关文献。结果肿瘤位于胰体,镜下示肿瘤内丰富血管网,血管周成巢、成片或器官样排列的上皮样细胞;细胞质透明至弱嗜酸性,部分可见色素颗粒;细胞核小,圆形、卵圆形,核分裂罕见。免疫组织化学显示肿瘤细胞HMB-45(+),PR、E-cadherin、TFE3局灶(+)。特殊染色(Fontana-Masson’s Stain for Melanin)证实肿瘤细胞胞质内可见棕褐色黑色素颗粒沉着。结论胰腺PEComa是一种生物学行为仍存争议的间叶源性肿瘤,有其独特的组织学形态及免疫组织化学表型,目前尚无明确的良、恶性诊断标准。

Objective To investigate the clinicopathologic features, diagnosis and differential diagnosis of pancreatic perivascular epithelioid cell tumor （PEComa） with melanin. Methods One case of PEComa of the pancreas was studied by light microscopy, Fontana-Masson silver stain, iron stain and immunohistochemistry. The clinical and pathologic features were analyzed and the relevant literatures were reviewed. Results The tumor was located in the body of the pancreas. Microscopically, the lesion was composed of the blood vessels and nest-shaped plump epithelioid cells around the blood vessels. The tumor ceils had abundant clear to eosinophilic cytoplasm. The nuclei were round to oval and no mitoses were observed. Immunohistochemistrically, the tumor ceils were strongly positive for HMB45, focally positive for PR, Ecadherin, and TFE3. Fontana-Masson＇s stain revealed the presence of melanin in cytoplasm of tumor cells. Conclusion Pancreatic PEComa is a mesenchymal tumor with undetermined biological behavior and has unique histological, immunohistochemical features. There are no definitely diagnostic criteria currently available to differentiate malignant from benign pancreatic PEComa.