Cystic lesions of the extraocular muscles

Cystic lesions of the extraocular muscles (EOMs) are uncommon. Six patients with a cystic lesion in an extraocular muscle, as observed by computerized tomography (CT) scanning, were retrospectively identified from the practice of one of the authors (G.C.S.), and their clinical course was reviewed. All the patients were treated initially with oral corticosteroids. Those who did not respond to this therapy underwent surgical exploration. Four patients demonstrated complete resolution of clinical signs and symptoms with oral steroid therapy. Posttreatment CT scans performed in two of these patients showed resolution of the cystic lesion with residual muscle thickening in one. The two patients not responding to steroids underwent surgical excision and histopathology confirmed the diagnosis of cysticercosis. Cysticercosis is a previously reported cause of a cystic lesion in an EOM. To the best of our knowledge, cystic lesions of the EOMs resolving with steroids have not been previously reported. Response to oral steroids in four of our patients is suggestive of myositis with a cystic change in the muscle. We recommend a trial of oral steroid therapy in patients with a cystic EOM lesion before surgical exploration is performed.