Porphyria cutanea tarda and systemic lupus erythematosus.

Fifty-five patients with porphyria cutanea tarda (PCT) were examined for the simultaneous occurrence of systemic lupus erythematosus (SLE). The diagnostic criteria for SLE were those set up by the American Rheumatism Association (ARA). No patient fulfilled the ARA criteria for SLE. Clinical and laboratory features characteristically associated with SLE (although they were not ARA criteria) were simultaneously evaluated. A total of 120 items occurred in those cases but only 15 of these were ARA criteria. These findings, which may suggest the presence of SLE in patients with PCT, might be ascribed to the concomitant liver disease. The simultaneous occurrence of SLE and PCT is reviewed from the literature. The ARA criteria were fulfilled in one third of the reported cases. The coexistence of SLE and PCT might be less frequent than formerly believed.