Systemic lupus erythematosus and dermatomyositis with symptomatic bilateral sacroiliitis: an unusual and interesting association.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune connective-tissue disease with a complex phenotype and varying disease course. Although SLE often causes a polyarticular synovitis, there are only a few case reports of abnormalities of the synovial lined sacroiliac joints. We report a case with an overlap syndrome of SLE and dermatomyositis who subsequently developed bilateral symptomatic sacroiliitis. We conclude that sacroiliitis, although rare, can occur in patients with active SLE as a manifestation of the disease per se.