Idiopathic orbital myositis (Gleason, 1903) is an inflammatory condition of the extra-ocular muscles in the absence of thyroid eye disease and is classified among the “orbital pseudo-tumours”. This paper reports three cases and reviews the literature. The authors conclude that the term “orbital pseudo-tumour” is no longer appropriate.

The diagnostic criteria proposed by them are the presence of acute orbital pain exacerbated by eye movements, enlargement of one or more extra-ocular muscles with otherwise normal orbital structures on CT scanning, the absence of clinical or biochemical evidence of thyroid dysfunction, the absence of evidence of anterior uveitis, scleritis or visual impairment and the rapid response to an immunosuppressive treatment.

51 references.