EXPRESSION OF THE C-KIT RECEPTOR IN HYPOMELANOSIS - A COMPARATIVE-STUDY BETWEEN PIEBALDISM, NEVUS DEPIGMENTOSUS AND VITILIGO

In order to investigate possible alterations in c-kit protein expressi on on epidermal melanocytes in different hypopigmentary disorders, we have examined skin specimens from one patient with piebaldism, one pat ient with naevus depigmentosus, and five patients with vitiligo. Cryos ections were examined by immunohistochemistry using monoclonal antibod ies against the c-kit protein (YB5.B8) and melanosomes (TA99). In pieb aldism, hypomelanotic epidermis contained only a few TA99-positive epi dermal melanocytes and no detectable c-kit protein, whereas in naevus depigmentosus the expression of c-kit protein was strong, and TA99 imm unoreactivity was faint. In vitiligo lesions, no epidermal immunoreact ivity for melanosomes or c-kit protein was found. Normally pigmented s kin of all patients showed immunoreactivity of epidermal melanocytes f or both c-kit protein and melanosomes. Different hypomelanotic lesions can thus be differentiated by absent melanocyte c-kit protein and low or no expression of melanosomal marker in piebaldism, normal c-kit bu t low melanosome expression in naevus depigmentosus, and the absence o f all melanocyte markers in vitiligo.