Recurrence of multiple myeloma with soft tissue plasmacytoma presenting as unilateral proptosis.

Purpose: To describe a rare case of soft tissue plasmacytoma of the orbit presenting with proptosis.

Results: A 57 year-old Malay lady presented with right eye proptosis of 3 weeks' duration. It was associated with pain, redness and progressive blurring of vision. The patient was diagnosed to have multiple myeloma a year previously when she was investigated for backache, and had been treated with eight cycles of Pamidronate chemotherapy. On examination visual acuity was 6/60 in the right eye with impaired optic nerve function. Severe proptosis with chemosis and complete ophthalmoplegia were found. The corneal and anterior chamber examinations were normal. Fundoscopy revealed a slightly hyperaemic disc with presence of choroidal folds infero-temporally. The left vision and eye examination findings were normal. Fine needle biopsy and MRI showed recurrence of multiple myeloma with soft tissue plasmacytoma of the extraconal region compressing the right optic nerve. She was managed with orbital radiotherapy, resulting in resolution of proptosis, but without improvement in vision.

Conclusion: Proptosis may be an indicator of recurrence of multiple myeloma in patients thought to be in remission.