[Chloroquine-induced achromotrichia. An ultrastructural study]

Electron microscopy examination of scalp biopsies from a patient with chloroquine achromotrichia gave elements concerning the pathogenesis of chloroquine-induced achromotrichia.

A 21-year old light brown-haired patient developed achromotrichia after four months of treatment with chloroquine for subacute lupus erythematosus. Hair bleaching completely regressed 5 months after discontinuing chloroquine despite replacement with hydroxychloroquine. During the achromatrichia phase, many ultrastructural anomalies were observed in the hair root melanocytes: the nuclei were small and densified, and there was an accumulation of immature melanosomes in the cytoplasm; these melanosomes, mainly in stage II, were rarely transferred to keratinocytes. After recovery from the achromotrichia, melanocytes displayed a normal aspect.

Pathophysiological disturbances leading to chloroquine induced achromotrichia are still unclear. The ultrastructural study of hair follicles in our patient show that under chloroquine action melanocytes become unable to perform complete melanin synthesis and to produce normally melanized melanosomes which may be transferred to keratinocytes. Non-melanized or poorly melanized melanosomes accumulate in the melanocytes which finally become inactive cells. These findings suggest that achromotrichia is induced by a toxic effect of chloroquine on the melanocyte.