The Distribution of Melanocytes in the Leptomeninges of the Human Brain

The purpose of this study was to determine the qualitative and quantitative distribution of melanocytes in human leptomeninges by histochemical and ultrastructural techniques and to search for melanocytes in the mesothelial linings of the pleural and peritoneal cavities. Knowledge of the extracutaneous distribution of pigment cells will facilitate the interpretation of systemic symptoms in depigmentation disorders, such as vitiligo and the Vogt-Koyanagi-Harada syndrome.In 15 brains examined, leptomeningeal pigment cells were found principally over the ventrolateral surfaces of the medulla oblongata. Only isolated pigment-containing cells were found in the meninges covering other parts of the brain. The mean number of pigment cells in the medullary meninges of 5 brains was 325/mm2 ± 96. The presence of melanosomes as single, membrane- bound granules in all stages of melanization confirms that the melanin-containing dendritic cells of the leptomeninges are melanocytes and not macrophages.No pigmented cells were observed in the pleural or peritoneal samples examined

Extracellular Granular Material and Degeneration of Keratinocytes in the Normally Pigmented Epidermis of Patients with Vitiligo

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 1–15cm 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 extracellular 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 whole 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