Orbital myositis--a case report.

Orbital myositis is an idiopathic inflammatory condition involving the extraocular muscles. A case of presumed orbital myositis is presented, displaying typical features on orbital computed tomography, and a dramatic response to corticosteroid therapy. Atypical features of acute-on-chronic course, and concomitant sinus disease are discussed. A differential diagnosis of enlarged extraocular muscles is also discussed, and the benefits of corticosteroid trial before formal biopsy in the appropriate clinical setting is emphasised.