Orbital involvement is a rare manifestation of multiple myeloma. When it does occur, however, proptosis is frequently the initial clinical manifestation of the disease, which should be kept in mind in the differential diagnosis of proptosis. Our study stresses the importance of a complete clinical, radiographic, and laboratory work-up in every case of proptosis to rule out multiple myeloma. Histopathologically, the differential diagnoses should include solitary extramedullary plasmacytoma, plasma cell pseudotumor, and in some instances, undifferentiated carcinoma, reticulum cell sarcoma, and amelanotic melanoma.
Rodman HI, Font RL. Orbital Involvement in Multiple MyelomaReview of the Literature and Report of Three Cases. Arch Ophthalmol. 1972;87(1):30-35. doi:10.1001/archopht.1972.01000020032006