Primary bone lymphoma of distal femur presenting as marrow edema and normal radiograph: A radiologic deception

Primary lymphoma of bone is a uncommon primary osseous malignancy. Its clinical features include pain and swelling at the local site with a variable appearance on initial investigation which is a plain radiograph. Secondary investigation is MRI which helps in early diagnosis, assess the extension and used for treatment evaluation. Early identification of primary bone lymphoma is crucial, since it has better prognosis compared to other primary bone malignancies. Thereby, we aim to discuss an interesting case of a female adult patient, diagnosed as primary bone lymphoma of the femur on MRI, who presented initially as deceiving features of only bone marrow edema and its distinct imaging characteristics developing only after a few months. The case report also elaborates the imaging features of primary bone lymphoma with review of literature.