A 26 year old male presented with a 10 year history of slowly progressing proptosis of left eye and intermittent diplopia. The patient did not have pain and there was no change in visual acuity. His past medical history was unremarkable. On exam he had 20/20 vision in both eyes normal colour vision and no relative afferent pupillary defect. There was a -1 supraduction and -1/2 abduction limitations and the left globe was down 3-4mm and displaced laterally 10mm. There was 10-12mm of axial proptosis of the left globe. CT scan showed a large mass located medially in the orbit which was displacing the optic nerve laterally. It was undistinguishable if the mass was involving or merely adjacent to the medial rectus muscle. A biopsy was conducted through the swinging eye lid approach. Intraoperatively, the mass was red and after orbital exploration the medial rectus could not be identified despite excellent exposure. There was prominent bleeding during the biopsy. Histopathology described the lesion as an intramuscular hemangioma; a dense meshwork of arterioles and venules intermingled between the muscle cells in the connective tissue and containing strands of endothelial cells, pericytes and mature fat cells. Despite his symptoms and varying treatment options offered, the patient declined active management. Intramuscular hemangiomas are exceedingly rare with only a few previously described as arising in an extraocular muscle. This process is distinctly different from the more commonly seen capillary hemangioma in children and cavernous hemangiomas seen in adults. Management of extraocular intramuscular hemangiomas is primarily based on isolated case reports as there are no large series available. Total excision can be challenging due to high risk of intraoperative hemorrhaging and chance of recurrence with incomplete excision. Intralesional corticosteroids may potentially decrease tumor bulk as may radiation. Conservative monitoring has been the mainstay of treatment for most cases.
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