Microcystic Adnexal Carcinoma

• Locally aggressive sweat duct carcinoma uncommonly seen in young or middle-aged adults
• Presents as indurated plaque resembling sclerosing BCC often in perioral, perinasal, periorbital, or lip area
• Histology: ill-defined neoplasm in dermis and subcutaneous tissue with islands of basaloid cells with small lumina and horn cysts in background of hyalinized fibrotic stroma, ± perineural invasion; of note, only rarely see cytologic atypia; appears more like syringoma in upper half and cord-like in lower half of tissue specimen
• Treatment: conventional excision or Mohs surgery; high recurrence rate