Basal Cell Carcinoma Possibly Originates From the Outer Root Sheath and/or the Bulge Region of the Vellus Hair Follicle

The study analyzed the immunophenotype and lectin binding profile of basal cell carcinoma (BCC) in comparison to human vellus hair follicular keratinocytes. It found that BCC shared an almost identical immunohistochemical profile with the suprabulbar region of the outer root sheath of vellus hair follicles (VHF), but not with other follicular compartments. Both BCC and the outer root sheath expressed basal differentiation markers CK 5 and CK 14, while CK 19 showed variable expression in BCC and constant expression in the outer root sheath and follicular bulge regions. The lectin binding profiles of BCC and the outer root sheath were also comparable. These findings suggested a closer histochemical relationship between BCC and the follicular epithelium of VHF than with the epidermis, indicating a possible origin or differentiation pattern of BCC from the outer root sheath and/or the follicular bulge region of VHF.