Syringofibroadenoma arising adjacent to verrucous carcinoma: Is it a reactive process, malignant transformation, or collision tumor?

Abstract

Eccrine syringofibroadenoma (ESFA) is a rare, benign tumor showing acrosyringeal or sweat gland differentiation with variable clinical presentations, but distinct histopathological features. Rarely, ESFA coexists with a malignancy such as a squamous cell carcinoma or porocarcinoma. Herein, we report the first case of an ESFA associated with a verrucous carcinoma in a 46-year-old female on the right foot. It is unclear whether it represents a reactive process, a malignant transformation or a collision tumor. We recommend ESFA be completely excised if possible or closely followed given its association with a developing carcinoma.