Incidental superficial soft tissue epithelioid angioleiomyoma.

Epithelioid angioleiomyoma (EALM) is rare in the skin and subcutaneous tissues. To the best of our knowledge, only two previous cases of this tumor have been reported. We document here the case of an 83-year-old woman who underwent complete removal of a squamous cell carcinoma of the retromolar trigone and lymph node dissection of the neck. An incidental EALM was observed in the adipose tissue. The tumor formed a unilocular, poorly demarcated neoplasm measuring 0.3 cm, and showed cavernous angiomatous spaces with villiform growth of large epithelioid cells arranged in clusters. Besides the epithelioid cells of muscular origin, bundles of well-differentiated smooth muscle cells were observed. Epithelioid cells accounted for 70% of the total. The neoplasm originated in the wall of a medium-sized vein. Epithelioid and spindle cells were positive for alpha-smooth muscle actin, calponin, h-caldesmon, and muscle-specific actin. The endothelial cells lining the vascular spaces showed intense and diffuse positivity for CD31 and ERG. The main differential diagnosis includes metastatic carcinoma, melanoma, perivascular epithelioid cell neoplasm, myopericytoma, glomangiomyoma, epithelioid glomus tumor, and epithelioid leiomyosarcoma. This report expands the morphological spectrum of the EALM. Awareness of this uncommon morphologic variant of angioleiomyoma and the use of adequate techniques can avoid misdiagnosis.