[Ultrastructural aspects of the epidermis from a sun exposed and from a covered area in two cases of xeroderma pigmentosum (x. p.) and in two controls (author's transl)].

Xeroderma pigmentosum is rare among Caucasoids and seems to be rarer among Negroes. Advantage was taken of the observation of two cases in the latters to study the ultrastructure of the epidermis and to verify whether the findings were similar to those observed in the formers. The skin exposed to sunlight (forearm) and that from an covered area (buttock) were studied in the two cases and also in two controls, obviously from the same race. The tissue material was coded after each biopsy and identified only when the ultrastructural study was completed. The authors have noted vacuolization and rarely necrosis of melanocytes, great increase and polymorphism of melanosomes, abnormal melanization sometimes large masses of melanosomes and pre-melanosomes, some other aspects already described in x.p. They have also observed melanosomes disposed as cluster or grapes, and large and strange shaped keratohyaline granules in the squamous cell layer. Even in the unexposed skin there were polymorphism and increased amount of melanosomes. The macroscopic and ultrastructural changes of x. p. in the two Negroes were apparently similar to those observed in Caucasoids.