Idiopathic guttate hypomelanosis: an electron microscopy study.

BACKGROUND: Few published data, concerning the electron microscopy findings of idiopathic guttate hypomelanosis have been published so far.

OBJECTIVES: To reveal the electron microscopic findings of idiopathic guttate hypomelanosis and their aetiopathogenetic associations.

METHODS: Punch biopsy specimens from four patients with idiopathic guttate hypomelanosis, after being properly processed, were observed under the electron microscope.

RESULTS: In the epidermis, melanocytes and melanosomes were normal in structure. In some areas, there was a reduced uptake of melanosomes by the keratinocytes. In the dermis, fibroblasts were structurally normal. Also, most elastic and collagen fibres were normal, but there were focal elastotic changes.

CONCLUSIONS: No significant structural abnormality of the melanocytes was observed, but rather a functional defect in the transfer of melanosomes from the melanocytes to the keratinocytes.