Primary precursor B-lymphoblastic lymphoma/leukemia (B-LBLL) of bone is uncommon neoplasm that accounts for less than 1% of primary bone tumors. It has been commonly reported in pediatric population but is rare in adults. We present a case of a 20-year-old man with multiple osteolytic lesions as sole presentation of acute lymphoblastic leukemia, whose diagnosis was established by bone biopsy. A peripheral blood smear and the bone marrow aspirate showed no blast cells. The patient received treatment according to BFM 99 protocol and achieved complete response confirmed by F-FDG-PET/CT.