Precursor B-Lymphoblastic Lymphoma Presenting as a Solitary Bone Tumor Mimicking Osteomyelitis on MRI

摘要

We describe a 22 year-old man with the rare diagnosis of precursor b-lymphoblastic lymphoma involving only the proximal tibia without evidence of leukemia. He presented with right knee pain and swelling of approximately three months duration and nonspecific radiologic findings and was initially treated for osteomyelitis of unknown etiology. Following histologic diagnosis, the patient received surgical excision of the lesion followed by chemotherapy and radiation. The patient was alive without evidence of disease at nine months follow-up. Introduction Primary precursor B-lymphoblastic lymphoma (B-LBL) of bone is an uncommon neoplasm and accounts for less than 10% of cases of lymphoblastic lymphoma (LBL) and less than 1% of primary bone tumors. It usually involves extranodal sites in young adults and occurs most often in the skin [3]. B-LBL presenting as a solitary bone tumor without involvement of blood, bone marrow, or other sites is extremely rare and less than 10 cases of this type have been reported in the English language literature [3,6]. To the best of our knowledge, only 3 cases of B-LBL involving only the tibia have been reported and this represents the fourth case [6]. B-LBL often presents with few specific radiologic and laboratory findings and thus, can be difficult to diagnose and is often not considered in the patient presenting with bone pain. Case Report A 22-year-old man began to have spontaneous pain and swelling of the right knee in May 2002. Suspecting a tendonitis at the insertion of the patellar tendon, he was treated at an outside hospital with non-steroidal anti-inflammatory medications. This treatment relieved some, but not all of the symptoms. Three months later, the patient presented to the clinic in our department complaining of pain involving the right proximal tibia, including the musculature in this area, when he did any weight-bearing activities. Also, he reported occasionally feeling pain at the region of interest, even while at rest. He had Magnetic resonance (MR) images from an outside hospital that showed an irregular, lytic lesion involving the proximal tibia. (Fig. 1)