[Lucio's leprosy]. / Lepra de Lucio.

A case of diffuse lepromatous leprosy with lepra reaction type II-Lucio's phenomenon-in a 24 years old male patient is reported. The histological examination of the necrotic lesions and of the apparently normal skin showed the presence of dense perivascular and perianexial lymphohystiocitic infiltrates with great quantities of bacilli. The first biopsy did not show a picture a leuccocytoclastic vasculitis but only areas of necrosis. The immunofluorescence studies revealed on direct examination complement deposits on vessel walls. The complement levels in blood were lowered and circulating inmunecomplexes were also detected. These data confirm the opinion that Lucio's phenomenon is caused by circulating inmunecomplexes fixed on dermal vessel walls causing skin necrotic lesions.