Spectrum of Biopsy Proven Extraocular Muscle Tumours of Non-Thyroid Origin.

To describe different types of primary extraocular muscle (EOM) tumours based on the results of imaging studies, peroperative clinical picture and their histopathological diagnosis. Case series. Al-Shifa Trust Eye Hospital, Rawalpindi, from July 2001 to January 2017. A retrospective analysis of 640 diagnosed orbital tumours was carried out using non-randomised sampling technique, and the prevalence of primary EOM tumours was determined. Based on the results of imaging studies, the clinical picture observed during surgery (orbitotomy) and the histopathological diagnosis, primary EOM tumours were divided into different types, accordingly. Nineteen (n=19) primary EOM tumours (frequency of 2.96%) had 12 types of histopathological diagnoses, and were categorised into inflammatory tumours (n=8, 42%), vascular tumours (n=4, 21%), lymphoproliferative tumours (n=3, 16%), neurogenic tumours (n=2, 10.5%) and myogenic tumours (n=2, 10.5%). The recti were involved more frequently than obliques (n=15, 78.94% and n=4, 21.06%, respectively). All the patients presented with proptosis of varying degree with some degree of globe rotation and had surgical excision/appropriate management. Visual acuity was not affected in any of the patients. Four (n=4, 21.05%) tumours were malignant (NHL, ASPS, myeloid sarcoma and rhabdomyosarcoma) and these patients underwent chemotherapy and/or radiotherapy. Biopsy-proven primary EOM tumours were devisable into five broad categories. Patients with primary EOM tumours presented with proptosis and impaired ocular motiliy. The primary EOM tumours involved both the recti and the obliques and were excised surgically with favourable outcomes in most cases.