The tumor formation may be the earliest manifestation preceeding other symptoms, signs and bone marrow evidence of systemic malignancy - leukemia/lymphoma. Here we present three cases of systemic malignancy in which bone lesions were the first manifested signs of the disease. All three cases were thought to be orthopedic cases and had been treated as so without genuing improvement. We would like to draw an attention to children who present with multifocal musculoskeletal pain and the importance of whole-body scaning. We describe interesting cases of diffuse large cell lymphoma and leukemia that initially presented as primary osteolytic bone lesion and discuss the differential diagnosis, literature review of non-Hodgkin's lymphoma arising in bone as the primary site (Tab. 1, Fig. 3, Ref. 18). Full Text (Free, PDF) www.bmj.sk.