Abstract

Spindle-cell predominant trichodiscoma, historically referred to as “neurofollicular hamartoma”, is a distinctive histologic variant of the fibrofolliculoma–trichodiscoma hamartomatous spectrum. This benign adnexal entity features ample stromal component consisting of spindle cells organized in fascicles with surrounding sebaceous lobules. Furthermore, a minor subset of spindle-cell predominant trichodiscoma can display a palisaded arrangement of stromal cells. To date, there has only been two such reported cases in the English literature. Here, we present a case of a solitary nodule on the nose of a middle-age female patient that was histologically compatible with spindle-cell predominant trichodiscoma with palisaded arrangement of stromal cells. A 48-year-old woman with a history of basal cell carcinoma was found on routine exam to have a discrete, solitary nodule on her left nares that was clinically suspicious for an adnexal neoplasm such as nodular basal cell carcinoma versus intradermal nevus. Shave biopsy of the lesion revealed a sclerotic dermal spindle proliferation with palisaded arrangement and peripheral compressed sebaceous lobules on hematoxylin and eosin. Additional immunohistochemical stains showed CD34+ lesional cells with admixed scattered Factor XIIIa+ dendritic cells while S100, SOX10, desmin and smooth muscle actin were negative. These histologic and immunohistochemical findings were in keeping with those of prior documented cases. The neural-like palisaded pattern of stromal cells when present in spindle-cell predominant trichodiscoma is highly evocative of schwannoma. However, recognition of the associated epithelial component peripheral to the central stromal component is crucial to arriving at the correct diagnosis.

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