Extramedullary
plasmacytoma is a type of
plasma cell dyscrasia that can present as solitary
tumor or secondary to
multiple myeloma. We experienced a case of intramuscular
plasmacytoma in the left thigh muscles of a patient secondary to
multiple myeloma. A 73-year-old male with relapsed
multiple myeloma and bilateral hip
arthroplasty complained of lxeft lower limb weakness and hip
pain 3 months after relapse. He underwent contrast-enhanced magnetic resonance imaging of lumbar spine and hip which was inconclusive. Subsequently, patient had multiple admissions for progressive lower limb weakness. His
clinical course was complicated by a biopsy-proven
plasmacytoma of the neck. He received localized
radiation therapy to the neck in addition to a change in
multiple myeloma chemotherapy regimen, resulting in resolution of the neck mass but his left lower extremity weakness continued to worsen. Repeat magnetic resonance imaging of hip and spine revealed an intramuscular mass in left thigh which was consistent with the diagnosis of extramedullary
plasmacytoma on biopsy. Localized radiation to the thigh accompanied with a change in
chemotherapy improved his symptoms and a significant reduction in size of
plasmacytoma was observed. When an unexplained lower limb weakness is encountered with a history of
multiple myeloma, secondary intramuscular
plasmacytoma should be considered.