Fibrous tumor of the superior oblique tendon in Proteus syndrome.

Proteus syndrome is a disorder of patchy, or mosaic, postnatal overgrowth. Mosaic somatic mutation of the AKT1 gene has been identified in over 90% of individuals meeting the diagnostic criteria for Proteus syndrome. Onset occurs in infancy and can involve any tissue of the body. The connective tissue and bone, skin, central nervous system, and the eye are commonly involved. Epibulbar tumors, strabismus, and posterior segment involvement have previously been reported. However, there have not been any reports of lesions affecting the extraocular tendons. We report a case of Proteus syndrome patient presenting with vertical strabismus secondary to a fibrous tumor within the superior oblique tendon. The tumor was successfully excised with complete resolution of the strabismus.