OBJECTIVETo study the clinicopathologic features, differential diagnosis and prognosis of primary bone anaplastic large cell lymphoma(ALCL).

METHODSTwelve patients diagnosed with primary bone ALCL were retrospectively reviewed. The clinicopathologic features, immunohistochemic findings and results of in situ hybridization for EB virus were analyzed.

RESULTSOf the 12 patients, the male-to-female was 7: 5 with a median age of 17.5 years (range from 9 to 64 years). Bone pain was the presenting symptom in all patients. Radiographic examination demonstrated solitary osteolytic lesion in 8 patients and multiple lesions in the rest 4 patients. Spine (7 cases) was the most common site to be involved, followed by ilium (5 cases), sacrum (2 cases), humerus (1 case) and collarbone (1 case). Ten patients were available with the follow-up data including 5 ALK-positive and 5 ALK-negative patients, and the follow-up time was 2 to 47 months. Interestingly, the 3 dead patients were ALK-negative whereas 5 of 7 ALK-positive patients achieved remission.

CONCLUSIONSPrimary bone ALCL is a rare type of non-Hodgkin lymphoma and it more frequently involves the axial skeleton. Boys and young males are more commonly affected. Patients usually present at an early stage and have a relatively favorable prognosis. Expression of ALK protein may be associated with a favorable prognosis in primary bone ALCL.