Track: Case Reports

Abstract:

Cutaneous mixed tumors or chondroid syringomas are benign tumors that most commonly present in the head and neck, particularly on the side of the nose, with an average age of presentation at 48 years. Cases classically show an epithelial component with ductal differentiation, featuring a cuboidal lining with a surrounding myoepithelial layer, and a mesenchymal component commonly showing chondromyxoid-like stroma. We present a case of a 55-year-old female presenting with a 1-cm firm mobile non-tender nodule near the left lacrimal duct that has been fairly stable for over 10 years. An excisional biopsy was performed. Microscopic sections showed a well-circumscribed, encapsulated nodule with heterogenous components. The dominant histopathologic component was follicular in nature with basaloid follicular bulbs and dilated follicles with flaky dense keratinous contents. On closer inspection, there were areas of mesenchymal differentiation with chondromyxoid stroma and adipocytic metaplasia, and duct formation lined by an outer myoepithelial and an inner epithelial cell layer with occasional features of decapitation secretions. Focally, there were areas of pilomatrical differentiation that showed beta-catenin nuclear expression. This was diagnosed as a cutaneous mixed tumor with prominent follicular and pilomatrical differentiation, a rare subtype of cutaneous mixed tumor. Only a few cases have been reported in the literature. This subtype can be mistaken for trichofolliculoma or pilomatricoma. Cutaneous mixed tumors are usually indolent, and surgical excision is curative. In rare cases, they may undergo malignant transformation. This case underscores the heterogeneous histopathologic features that cutaneous mixed tumors can demonstrate.

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Sophia Zhang