M 35, left upper eyelid nodule
Diagnosis: Cutaneous mixed tumor (Chondroid syringoma)
Solitary, circumscribed dermal or subcutaneous nodule.
Mostly in head and neck of middle-aged man.
Tumor is composed of epithelial components within a fibromyxoid stroma.
Epithelial component forms branching tubules, ducts and dilated cystic spaces containing eosinophilic acellular material.
Epithelial cords with focal ductal lumen and cystic change within a myxoid, mesenchymal, myoepitheliod or chondroid stroma.
Cytology is bland.
Tumor is eccrine or apocrine in origin.
Cutaneous mixed tumor is an uncommon, benign adnexal neoplasm arising from apocrine or eccrine glands of the dermis. The tumor predominantly affects middle-aged man and presents as a slowly growing, painless, firm papule or nodule, most often involving the head and neck.
Histologically, the tumor is well-circumscribed and shows a biphasic growth pattern: an epithelial component and a stromal component having myxoid, fibrous, or chondroid differentiation. The epithelial component is composed of trabeculae, tubules, or ducts.
Classification into eccrine or apocrine type is based on the epithelial lining cells of the sweat duct lumina.
Immunohistochemical analysis of apocrine mixed tumors shows various staining patterns similar to the those of hair follicles, sebaceous glands, and all components of apocrine glands (folliculosebaceous-apocrine unit).
While mixed tumor of the skin is almost invariably benign, cases with cytologic atypia or malignancy are reported in the literature where the tumor shows architectural or cytologic atypia. The tumor may show good circumscription and lack of capsular breach or hypercellularity with some asymmetry and infiltrative and pushing borders. After complete excision recurrences or metastases are almost unknown within follow-up period of 5 years. Rare recurrence is seen in only in tumors with infiltrative borders.
Deba P Sarma, MD, Omaha
Download: Cutaneous mixed tumor