Abstract
Because of their specificity, hair sheath keratins (Moll’s keratin catalog, No. 6, 16, 17) can be markers of hair sheath tumors. Hair sheath keratins were identified in all seborrheic keratoses investigated by both two-dimensional gel electrophoresis and immunoblotting after extracting the keratins from the tumors. As compared with hair sheath keratins, epidermal keratin (Moll’s catalog No. 1) in seborrheic keratosis was small in size according to the densitometric analysis of electrophoretic spots. A histopathological study of 164 cases of seborrheic keratosis suggested that they originated from the infundibulum and isthmus of the hair follicle. Pathological features such as continuity of tumor to the upper part of hair follicle, the coexistene of intermediate and clear cells within the basaloid tumor cells were also seen. The identification of hair sheath keratins coupled with the histopathological findings strongly suggested that seborrheic keratosis may originate from the upper part of the hair follicle.
