Panfolliculoma: report of two cases

Panfolliculoma is a distinctive and unusual benign follicular neoplasm. It shows differentiation towards all components of the hair follicle, including the upper and the lower segments. We report two cases of this rare disease. The first patient presented with a painful nodule on the scalp and the second patient had an asymptomatic skin-colored nodule on his left eyebrow. Histopathologic examination of both cases revealed lobular proliferation of solid-cystic follicular structures. The cystic structures contain laminated keratin, indicating infundibular differentiation. The solid tumor part was composed of basaloid germinative cells, matricial cells, and cells with trichohyalin granules, representing inner root sheath differentiation. The range of differentiations was highlighted using immunohistochemical stains, including labeling of cytokeratin 1, 5, 10, 14 (using 34bE12), cytokeratin 5/6, CD34 (outer root sheath), and Ber-EP4 (lower segment of hair follicle). Panfolliculoma should not be confused with trichofolliculoma or trichoblastoma.