Hypomelanosis of Ito: electron microscopical observations on two new cases

An ultrastructural study on two new cases of Ito's hypomelanosis is reported. According with previous studies on this pathological condition, a marked reduction of melanocytes is detected in the hypopigmented areas. In the proximity of preserved melanocytes, a nearly normal content of melanosomes is detected in basal keratinocytes. Melanocyte profiles are frequently located in close relationship with the basal lamina. An apparent increase of nerve endings is demonstrated at the dermo-epidermal edge. Nerve fibres show no pathological alterations. A functional impairement of the melanocytes is hypothesized, involving regressive changes and a tendence towards a round shape of their profiles. This could in part account for the prevalent basal location of the melanocytes. The role of the dermal nerve endings in the pathogenesis of the hypopigmented lesions is discussed.