Rapid progressive extramedullary plasmacytoma in the orbit

Plasma cell tumors of the orbit are uncommon and mostly the first manifestation of a multiple myeloma (MM). Primary extramedullary plasmacytoma (EMP) of the orbit is exceedingly rare and only a few cases have been reported so far. Differentiation of an EMP from a MM is important, since 9.5 years have been reported as the mean survival of EMP, compared with a mean survival of 3 to 4 years for multiple myeloma.

A 68-year-old man presented with a history of rapid progressive extramedullary plasmacytoma in the right orbit, increasing in size within a few weeks. MR imaging revealed an intraorbital mass measuring 5.2 x 4.7 x 3 cm. The earlier performed biopsy was positive for plasmacytoma of the lambda light chain type. Systemic work-up was negative for further tumor spread.

Irradiation (a maximum of 80 Gy) and several chemotherapy cycles showed no effect. Exenteration with sparing of the upper and lower lid skin was performed. The residual defect was covered by a Thiersch graft. Although the orbit had been irradiated with the maximal dose, the Thiersch graft healed well.

Normally, EMP is slow to increase in size. In our patient, marked growth of tumor was noted within one week. One underlying reason is the poorly differentiated, blastic morphology leading to this rapid tumor growth. However, particular molecular features, like a t(4;14), could not be demonstrated.