A Pedunculated Follicular Hamartoma: A Case Showing a Central Trichofolliculoma-Like Tumor with Multiple Trichogenic Tumors

The document reported a rare case of a pedunculated follicular hamartoma in a 77-year-old Japanese male, characterized by a nodule on the nasal septum. The nodule measured 11x11x10 mm and was skin-to-pink colored. Histopathological examination revealed a well-formed dilated hair follicle at the tumor's central pore, containing keratin debris and vellus hairs. Epithelial cells proliferated from the central follicle to the peripheral epidermis, forming long thin strands or immature follicle-like structures. A primary germinal bud with thick concentric collagen fibers and sparse elastic fibers was also noted. Although the tumor had features of a trichofolliculoma with desmoplasia, trichogenic trichoblastomas, and perifollicular fibromas, it was more accurately described as a pedunculated follicular hamartoma due to its distinctive clinical and pathological features.