Solitary plasmacytoma of tibia: BMJ case report
A 58-year-old diabetic man presented to the outpatient department with pain in his right leg of 6 months’ duration. The pain was insidious in onset and gradually progressive. He was unable to bear weight on the affected side. On clinical examination, there was tenderness over the medial aspect of the upper part of the leg. The knee range of movements was limited and painful. The distal neurovascular examination was normal.

Plain X-ray of the knee showed an eccentric lytic lesion in the proximal end of the tibia with a pathological fracture of the medial wall. There was no periosteal reaction. Plain and contrast MRI study revealed a well-defined heterogeneously enhancing altered signal eccentric intramedullary lesion in the proximal meta-diaphyseal region of the tibia with cortical breaks.

The patient was taken up for open incisional biopsy, and prophylactic fixation of the proximal tibia was done using 4.5 mm proximal tibia lateral locking plate. The histopathology features were suggestive of plasmacytoma. The serology work-up for myeloma was performed.

A skeletal survey did not yield any other lesions. The light chain analysis kappa was increased, and the Kappa/Lambda ratio was high, suggestive of monoclonal gammopathy. The patient is currently undergoing radiotherapy.

Learning points
• Solitary plasmacytoma involving the long bones, especially tibia, has been rarely reported.

• A high index of clinical suspicion with proper serological, radiological and histopathological evaluation aid in prompt diagnosis and appropriate treatment.

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