Cystic panfolliculoma.

Panfolliculoma is a rare follicular neoplasm with differentiation toward both upper (infundibulum and isthmus) and lower (stem, hair matrix, and bulb) segments of a hair follicle. We present an unusual case of cystic panfolliculoma. A 33-year-old Hispanic woman presented with an 8-month history of a 3.0-cm cystic scalp mass. The lesion was excised, and the histologic sections showed a cystic follicular neoplasm that contained corneocytes in basket-woven and laminated array, trichohyalin granules of the inner root sheath, germinative cells, papillae, matrical cells, and "shadow" cells. Cytokeratin 903 and cytokeratin 5/6 immunostains uniformly highlight the tumor cells. Ber-EP4 strongly labels the germinative cells but not the follicular papillae. CD34 labels the surrounding fibrotic stroma and focally the epithelial component.