Extracellular granular material and degeneration of keratinocytes in the normally pigmented epidermis of patients with vitiligo

Abstract

Multiple biopsy specimens from the skin of 28 patients with common vitiligo were examined by light and electron microscopy. The patients were grouped according to the activity of their disease: progressing, stable, repigmenting, and resistant to treatment with psoralen plus sunlight. Three biopsy sites were sampled from each patient: (W) a white spot; (I) the pigmented and white interface; and (P) normally pigmented skin 1-15 cm away from I. Control specimens were obtained from 17 persons without vitiligo. Two microscopic abnormalities were observed in the epidermis of the patients with vitiligo: deposits of extra cellular granular material, and foci of vacuolar degeneration of basal and parabasal keratinocytes. The extracellular granular material appeared to be derived from the cytoplasm of vacuolated keratinocytes. The abnormalities were observed in greatest abundance in the normally pigmented skin of patients with rapidly progressing or stable disease. They were absent from repigmenting skin and from the skin of healthy controls. Epidermal infiltrates of mononuclear leukocytes were seen only in the normally pigmented skin of the 2 patients whose vitiligo was resistant to treatment. Our observations indicate that cellular degeneration and the generation of debris in vitiligo are not limited to melanocytes but include keratinocytes and probably whose epidermal melanin units. Our findings also indicate that the fine structure of the epidermis in normal-appearing skin is markedly altered by the disease process in patients with vitiligo.