A skin biopsy specimen revealed that each horny projection was composed of a single, well-defined, compact, parakeratotic column without evidence of dyskeratosis, acantholysis, cytologic atypia, or vacuolation of keratinocytes in the underlying epidermis. The parakeratotic column arose directly from the granular layer, which appeared thinned at this area. Neither continuity of the keratotic lesions with the acrosyringium nor an underlying dermal eccrine duct was present. The dermis was unremarkable. Based on the clinical and histopathologic findings, a diagnosis of filiform hyperkeratosis of the palms was made, and keratolytic creams were prescribed, with little improvement of the lesions.
Filiform Horny Projections on the Palms of a 69-Year-Old Man—Diagnosis. Arch Dermatol. 2006;142(2):235-240. doi:10.1001/archderm.142.2.235-h