The coexistence of psoriasis with lupus erythematosus and other photosensitive disorders

Abstract

The coexistence of psoriasis with LE or other photosensitive disorders is rare in our patient population, occurring in 0.69% of patients with psoriasis and 1.1% of those with LE. PMLE was the most common cause of photosensitivity in psoriatic patients without LE, occurring in 32%. Less common causes included drug-related photosensitivity (thiazides and thiazide derivatives in four of the five cases), PUVA reactions, and photocontact reactions. The Goeckerman regimen or UVB applied in a cautious, well-controlled atmosphere was generally well tolerated in this group, including patients with PMLE. Photosensitivity occurred in 50% of our patients with psoriasis and LE, and it was secondary to LE in 70% of cases. Most patients were female and had SLE. Psoriasis developed first in 55% of the cases. Studies that were useful for distinguishing photosensitive from nonphotosensitive patients with SLE included determination of antibodies to extractable nuclear antigens (67% versus 14%), double-stranded DNA (64% versus 9%), and skin biopsy for direct immunofluorescence (58% versus 27%). Occasional patients have features suggestive of photosensitivity with or without signs or symptoms of LE. These patients may have atypical psoriatic plaques occasionally yielding routine histology diagnostic of psoriasis with direct immuno-fluorescence results suggestive of lupus. Frequently, connective tissue serology findings are positive, and affected patients require close follow-up for the development of LE. In patients with psoriasis and suspected photosensitivity, we recommend a careful history and examination, skin biopsy for routine histology and direct immunofluorescence, blood tests including determination of antibodies to antinuclear antibodies (Hep-2 substrate if negative on routine substrate), extractable nuclear antigens, and double-stranded DNA, and phototesting when indicated. Large-scale prospective studies are required before the most appropriate therapy for patients with psoriasis and LE can be recommended.