PUVA-induced melanocytic atypia: is it confined to PUVA lentigines?

Widespread lentigines in fourteen patients following long-term therapy with psoralens and ultraviolet A (PUVA) for psoriasis were documented by biopsy of a representative lesion in a non-sun-exposed site. Chronically PUVA-exposed nonlesional skin was examined in ten of the fourteen patients. Melanocytic atypia consisting of large or angular hyperchromatic nuclei was observed in 57% of PUVA lentigines and 70% of the nonlesional PUVA-exposed skin. Comparison with twenty-four specimens of lentigo simplex or solar lentigines revealed melanocytic nuclear atypia in only two cases. Binucleated melanocytes suggesting disturbed cellular kinetics were seen in all types of lesions examined but most commonly in PUVA lentigines. The presence of giant melanosomes was also a frequent nonspecific finding. Our findings of melanocytic atypia in chronically PUVA-exposed skin, as well as in PUVA lentigines, suggest that both sites are at risk for potential complications of repeated melanocytic stimulation. Whether melanocytic atypia will prove to be a precursor of melanocytic dysplasia or malignancy following PUVA therapy requires long-term evaluation.