Purpose: To report a case of extramedullary plasmacytoma of the orbit.
Methods: A 71-year-old patient presented with diplopia eyelid fullness and limitation of ocular motility in the left eye. Visual acuity was counting fingers, intraocular pressure 34 mmHg and fundus eye examination showed choroidal folds in the involved eye.
Results: CT scan showed a mass filling the superior and external left orbit without bone destruction. A biopsy was performed revealing that the tumour was composed of plasmacytoid cells positive with immunohistochemical stains for Kappa light chains and epithelial membrane antigen. Systemic work up was negative. The diagnosis of extramedullary orbital plasmacytoma was made. The patient was treated with external beam radiotherapy (40 Gy) and has remained disease free for four years (49 months).
Conclusion: Extramedullary plasmacytomas of the orbit are extremely rare tumours. Accurate and early diagnosis is essential for the therapeutic approach. Extensive medical work up to rule out multiple myeloma or other malignant lymphoproliferative conditions involving the orbit is needed when the diagnosis of orbital extramedullary plasmacytoma is suspected because treatment and prognosis are very different.