Clinical, histopathological and ultrastructural characteristics of naevus depigmentosus

Naevus depigmentosus (ND) is a congenital, nonfamilial, well-circumscribed, uniformly hypopigmented macule, the relative size and distribution of which is stable throughout life. The aetiopathogenesis of ND is not yet fully understood, and reports about the clinical and histopathological characteristics of ND are few.

To investigate the clinical and histopathological characteristics of ND, and to make it easier to diagnose ND clinically.

A clinical survey on 38 patients with ND was performed according to the diagnostic criteria proposed by Coupe. Wood's lamp examination was used to distinguish the different appearance of ND and vitiligo. Skin-biopsy specimens were stained with haematoxylin and eosin, silver, antibodies to S-100 protein, tyrosinase-related protein-1 and tyrosinase, then used for ultrastructural study. Melanocytes were also cultured.

Leucoderma was present at birth in 13 patients (34.2%), and appeared during the first 3 years of life in 15 patients. The trunk was the most commonly affected site, and the lesions usually had serrated, irregular borders. Under Wood's lamp, lesions had an off-white accentuation without fluorescence. Immunohistochemistry showed that the melanin content of ND lesions was decreased compared with perilesional normal skin, but there was no change in the number of melanocytes. Ultrastructural study showed that some aggregated melanosomes were present in the affected keratinocytes.

As a result of the above findings, we suggest changes to Coupe's criteria for ND.