Xeroderma pigmentosum. Ultrastructural study with special reference to abnormalities of the melanin pigmentary system.

Unusual changes in the melanin pigmentary system were observed on a warty papule biopsy taken from a patient with xeroderma pigmentosum (XP). Degenerated melanocytes full of lipids were observed from the basal layer up to the middle of the epidermis. The melanosomes were polymorphous, variable in size and shape with very strange aspects, such as spider-like and whirling configurations. The structure of the macromelanosomes suggests that they are large autophagosomes. These findings are discussed and compared with previous studies.