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Source: | Posted 17 years ago

Photoprovocation test and immunohistochemical analysis of inducible nitric oxide synthase expression in patients with Sjögren's syndrome associated with photosensitivity.

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Ultraviolet light is critical to the development of annular erythema in Sjogren's syndrome.

Dr. N. Tsukazaki, of the Department of Dermatology, Nagasaki University School of Medicine, Nagasaki, Japan, and colleagues performed a study to evaluate photosensitivity in Sjogren's syndrome and investigate the involvement of ultraviolet radiation in the development of annular erythema. (Annular erythema usually develops on areas of sun-exposed skin and is exacerbated during summer.)

They studied 14 patients with Sjogren's syndrome, including 10 with primary Sjogren's syndrome. Eleven of the 14 patients had a history of photosensitive annular erythema, papules or other types of lesions induced or aggravated by sunlight. Various data from the 14 patients were compared with data from patients with lupus erythematosus.

Phototesting was found to induce a prolonged erythematous response, infiltrated erythema and/or papules in eleven of the 14 patients, including one with primary Sjogren's syndrome without a history of photosensitivity.

The induced infiltrated erythema and papules showed coat-sleeve-like or sparse perivascular infiltration of lymphocytes similar to that in primary skin lesions of annular erythema in Sjogren's syndrome. No epidermal changes characteristic of lupus erythematosus were found, except for partial and mild liquefaction degeneration in three patients. However, two patients were indistinguishable from the papular type of polymorphic light eruption in several aspects.

In the three Sjogren's syndrome patients with minimal liquefaction degeneration, there was diffuse expression of inducible nitric oxide synthase throughout the epidermis. This is characteristic for lupus erythematosus. The remaining seven patients either did not show inducible nitric oxide synthase staining or expressed it normally.

Said Dr Tsukazaki, "Our results indicate that photosensitivity exists in certain primary Sjogren's syndrome patients, and that ultraviolet light is critical to the development of annular erythema in Sjogren's syndrome, probably through a pathological mechanism distinct from that in lupus erythematosus."