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Background: Osteoblastoma is a rare primary benign bone tumor that has varied radiologic presentation depending on the affected site. In selected cases, differential diagnosis with subacute osteomyelitis is necessary. Case Report: The authors present the case of a 23 year-old male with recurrent paronychia diagnosed with osteoblastoma of the femur. On the basis of CT and MRI findings, osteosarcoma, ABC, enchondroma, chondromyxoid fibroma, and Brodie's abscess were excluded from differential diagnosis, with the last option being the second most probable diagnosis given the coexistence of chronic pyogenic process. Discussion: Plain film findings in osteoblastoma and Brodie's abscess may be strikingly similar with an osteolytic lesion surrounded by prominent sclerosis. The nature of the lesion can be further elucidated by cross-sectional imaging. CT helps to assess the lesion matrix and presence or absence of sequestra or fistulae, while MRI defines the extent of the changes in bone marrow cavity and soft tissues.