Lateral Rectus Muscle Enlargement in Multiple Myeloma

Multiple myeloma (MM) is a systemic disease that is part of a spectrum of disorders ranging from monoclonal gammopathy of unknown significance (MGUS) to plasma cell leukemia, characterized by a proliferation of malignant plasma cells and production of monoclonal proteins. Extra-skeletal involvement in MM is rare and orbital involvement are extremely rare. The most common clinical presentation includes mass effect with subacute , painful or painless swelling involving the eye and periocular tissue, proptosis, diplopia, and decreased vision.We report a 73 year-old man with a recent diagnosis of MM who developed rapidly progressive painful right eye proptosis, diplopia and vision loss.