Case of polyostotic primary bone lymphoma successfully treated with immunochemotherapy and consolidation radiotherapy.

A 47-year-old woman presented with symptoms of sharp pain over the left anterior thigh with radiation from the groin to the knee. She subsequently developed numbness in that region and reduced motor strength in extensors of the left knee. Plain radiography of the spine and knee was normal. An MRI of the spine revealed an irregular extramedullary mass with intradural and extradural components, extending from the L3 to L5 vertebrae. She underwent a laminectomy and posterior spinal decompression based on a working diagnosis of nerve sheath tumour. Histopathology revealed a primary bone lymphoma. A positron emission tomography CT (PET-CT) performed as part of the staging workup revealed fluorodeoxyglucose avid lesions in the spine and left femur. She received immunochemotherapy (Rituximab-Cyclophosphamide, Hydroxydaunorubicin, Oncovin and Prednisone) for eight cycles with an interim PET-CT revealing complete response. Subsequently, she received consolidation radiotherapy, 36 Gy in 20 fractions over 4 weeks to both lesions. She is now disease-free on follow-up for the past 1 year.