[Acute idiopathic orbital myositis].

Idiopathic acute orbital myositis is a subgroup of inflammatory orbital pseudotumor. The case of a 35 year-old woman who suffered a left ocular pain with eyelid swelling, conjunctival hyperemia and limitation of abduction of the left eye is reported. CT showed an enlargement of the left medial rectus muscle enhanced with contrast. The pathogenesis remained obscure. The evolution was favourable with corticosteroids.