Abstract
BACKGROUND Anaplastic large cell lymphoma (ALCL) is a relatively rare subtype of non-Hodgkin's lymphoma (NHL). Like other types of NHL, ALCL primarily involves the nodal area, and sometimes it can involve several extra-nodal sites such as skin, soft tissue, and lungs. However, extensive bone involvement in cases of ALCL is very rare whether it is primary or secondary. Without nodular involvement, ALCL can be misdiagnosed as bone tumor or metastatic carcinoma such as lung, breast, or prostate cancer, which frequently spread to bone. CASE REPORT A 52-year-old woman with generalized pain and 2 months of fever of unknown origin presented to our institution. After extensive evaluation, only multiple osteolytic bone lesions with periosteal soft tissue reaction were identified. Repeated core needle biopsy revealed only inflammatory cells with histiocytic reactions. After pathologic and chromosomal analysis of sufficient tissue, which was acquired from incisional biopsy, primary bone ALCL was confirmed. CONCLUSIONS Clinicians should keep in mind that ALCL can present with extensive bone involvement without nodal involvement.