Studies on Cafe au lait Spots in Neurofibromatosis and Pigmented Macules of Nevus Spilus

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Abstract
Cafe au lait spots from 14 Japanese patients with neurofibromatosis and nevus spilus from 9 Japanese patients were subjected to studies on the differences in the nature of their melanocytes. When the number of melanocytes of the pigmented lesions was compared with that of the surrounding normal skin, the former was always increased and that of the cafe au lait spots was higher than that of nevus spilus. Giant pigment granules were recognized only in 6 patients out of 14 with neurofibromatosis but not in the nevus spilus. Two days after UV irradiation at 4 .times. ED50, the number of melanocytes was increased in both the surrounding normal skin and in the pigmented lesion, and the rates of increase were lower in the pigmented lesion. Under EM, melanocytes in cafe au lait spots which received UV light irradiation showed various changes in their cytoplasm; a development of dendrites containing many mature melanosomes, an increased number of cytoplasmic vacuoles and mitochondria, a development of Golgi apparatus in their cytoplasm, appearances of some dense-bodies and of autophagosomal melanosome-complexes. In nevus spilus, the same kind of changes occurred, but they were moderate compared with those developed in cafe au lait spots. Melanosomes in the keratinocytes of cafe au lait spots tended to come together around the nucleus and to form melanosome-complexes; while melanosomes in the keratinocytes of nevus spilus seemed to be singly dispersed after irradiation. The causative factors of the hyperpigmentation and the different reactivity of melanocytes against UV irradiation in these 2 pigmented macules were discussed.

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