Abstract

Spindle cell-predominant trichodiscoma (SCPT) is a histologic variant that is part of the trichodiscoma-fibrofolliculoma continuum. Trichodiscomas present clinically as small, dome-shaped papules, usually on the face, particularly the nose or the nasolabial fold. Histologically, they are characterized by a strong central cellular stroma encircled by sebaceous lobules that resemble mittens. The SCPT variant has been described as a particularly cellular trichodiscoma composed of small interweaving fascicles and sheets of spindle cells. Identical lesions were previously referred to as a neurofollicular hamartomas due to their predominant fascicular stromal cellularity and focal S-100 positivity. Herein, we report a rare variant of SCPT with a palisaded arrangement. The patient was a middle-aged man with no significant dermatologic history who presented with a skin-colored papule on the left ala of his nose. It had been present for approximately ten years with only mild growth over that time. A biopsy was obtained. Histopathological analysis revealed a dermal papule composed of bland spindle cells arranged in a striking palisading pattern within a fibromyxoid stroma with associated peripheral sebaceous glands. The palisaded pattern shared features reminiscent of Verocay bodies in a schwannoma. Immunohistochemical studies revealed stromal spindled cells with a strong and diffuse CD34 pattern and no S100 expression. To our knowledge, only two cases of SCPT with a palisaded pattern have been presented. SCPT with a palisaded pattern is a rare histologic variant that may resemble a schwannoma but may be recognized by its strong epithelial components and immunohistochemical staining.

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