[Hyperpigmentation of the oral mucosa in HIV infection]

In ten HIV-infected patients oral hyperpigmentations (HP) were observed, which seemed to be unrelated to any of the known endogenous or exogenous etiological factors. Light microscopy revealed accumulation of Fe-negative pigment in keratinocytes of the stratum basale as well as extra- and intracellularly within the subepithelial connective tissue. The ultrastructure of HP was characterised by the occurrence of melanosomes and premelanosomes within keratinocytes, melanocytes, macrophages and occasionally in fibroblasts, while especially in keratinocytes of the superficial cell layers immature melanosomes were found. Immunohistochemical examination pointed to an increase of HLA-DR positive cells and an altered distribution pattern of immunocompetent cells within the hyperpigmented mucosa. The finding of oral HP in HIV-infected patients may occur due to an increased activity of melanocytes, an increased production of melanosomes and their increased transfer to keratinocytes.