Squamoid Eccrine Ductal Carcinoma: Diagnostic Challenges, Histopathologic Criteria, and the Emerging Role of Mohs Micrographic Surgery in Management 5

Squamoid eccrine ductal carcinoma (SEDC) is an uncommon adnexal neoplasm that most often affects elderly patients and arises on sun-exposed skin. It poses a diagnostic challenge as it clinically and histologically resembles squamous cell carcinoma (SCC) and other adnexal tumors, frequently resulting in misdiagnosis. Accurate identification relies on deep incisional or excisional biopsies that capture the ductal component, supported by immunohistochemical markers, though these are not entirely specific. SEDC exhibits infiltrative growth and frequent; perineural invasion, contributing to high recurrence rates after wide local excision (WLE). Case reports increasingly support Mohs micrographic surgery (MMS) as the preferred surgical management technique due to its low rate of recurrence and complete margin control.