Malignant Eccrine Spiradenoma of the Face.

Malignant eccrine spiradenoma, or spiradenocarcinoma, is an exceedingly rare sweat-gland tumor, with only 102 reported cases. Low-grade carcinomas are especially rare with only a few cases reported. Because of the limited number of case reports, the biologic behavior of low-grade malignant eccrine spiradenoma is poorly understood and no evidence-based therapeutic approach is established. Here, the authors report a 29-year-old woman who presented with a history of left-sided facial lesions present since the age of 2 months. Histopathologic examination revealed multiple benign spiradenomas, several of which showed foci of low-grade malignant transformation evidenced by loss of the characteristic 2-cell population seen in the benign tumor component. Included are the clinical presentation, histopathologic description, and surgical decision making in an effort to guide recognition of this rare entity.