Orbital apex syndrome: a rare presentation of extramedullary hematopoiesis: case report and review of literature.

We describe a case of compressive neuropathy in the orbital apex due to extramedullary hematopoiesis (EMH). A 64-year-old man with Polycythemia Rubra Vera developed unilateral visual loss, proptosis, complete ophthalmoplegia, and facial paresis. Bone marrow biopsy showed myelofibrosis. Magnetic resonance imaging demonstrated enhancement at the orbital apex and subtle optic canal narrowing. Decompression of the optic nerve with biopsy of surrounding bone showed EMH. The patient received a course of radiation without benefit. We suggest including the diagnosis of EMH of the orbital apex bones in the differential diagnosis of patients with myeloproliferative disorders who develop an orbital apex syndrome.