Hepatic perivascular epithelioid cell tumor (PEComa): analyses of 13 cases and review of the literature.

Aim: To study the clinicopathologic characteristics of perivascular epithelioid cell tumor (PEComa) in the liver and to improve the understanding and diagnosis of this tumor. Methods and results: 13 cases of primary liver PEComa were retrieved from our hospital from January 2007 to September 2017. The clinicopathologic features and the computer tomographic (CT) or/and magnetic resonance imaging (MRI) tests of each case were retrospectively reviewed. All 13 patients were female, with ages ranging from 22 to 72 years (median, 35 years). The sizes of the tumor ranged from 1.0 to 19.8 cm. Histologically, the tumors were comprised of polygonal cells with clear to granular eosinophilic cytoplasm and were accompanied by positive immunohistochemical expression of HMB-45 and/or Melan-A. 6 cases showed moderate cytological atypia. Hemorrhage was present in 7 of 13 cases, and necrosis in 2 cases. Mitoses were scant, averaged from 0 to 1/50 high-power fields in every case. No vascular invasion was present in any case. Follow-up data were obtained from 9 of 13 cases, and none showed any evidence of tumor recurrence or metastasis. Conclusions: There are no specific symptoms of hepatic PEComa, and the preoperative imaging tests are also insensitive. In view of diverse histological growth patterns with atypical cell features in part of cases, the possibility of PEComa should be considered whenever unfamiliar hepatic tumors are encountered. Immunoreactivity for HMB-45, MelanA, and SMA, especially HMB-45, is very useful for the diagnosis of this tumor. IJCEP