Oculomotor muscles (OMM) involvement in dermatomyositis (DM) and in rheumatoid arthritis (RA) is unusual. The DM always leads to OMM inflammation, whereas the RA particularly leads to tenosynovitis of the superior oblique muscle referred to as the Brown syndrome.
The patient is a 43-year-old woman who gives a 17-year-history of severe seropositive RA with bilateral coxite. She was hospitalized for acute painful proptosis. The clinical examination revealed an orbital erythema and a muscular rhizomelic weakness. The muscular enzymes were increased. The orbital CT revealed in the right side, an enlargement of the superior rectus muscle that was enhanced after intravenous injection, which is compatible with myositis involvement. The muscular biopsy practiced at the level of the calf showed the specific histological signs of the DM. This orbital involvement was resolved with a high dose of corticosteroids.
Our observation has the specificity of associating RA with DM with an involvement of the superior rectus muscle, which is due to the DM rather than the RA.