Background: Although malignant bone tumours are infrequently encountered compared to the occurrence of other neoplastic lesions, they are of great significance because majority of them affect adolescents and young adults with a tendency of aggressive course. Morphological diagnosis of these tumours can be highly challenging. Objectives: 1. to know the incidence of malignant tumours of bone in this institute. 2. To study the histomorphological features of these lesions. 3. To classify these lesions by WHO classification and study the incidence of different lesions with respect to age, sex and site. Methodology: Biopsies and specimens received at the department of Pathology, KIMS, Hubli from July 2006 to June 20111 were subjected to routine fixation, processing and sectioning. Results: Out of the total 115 tumour and tumour like lesions of bone that were encountered during the study period, malignant bone tumours were 31 (26.9%), benign bone tumours 71 (61.73%), and tumour like lesions 13 (11.3%). Peak incidence of the malignant tumors was seen in third decade of life (34.7%). Osteosarcoma was the commonest malignant tumor (58%) followed by Ewing’s sarcoma (16.2%) and chondrosarcoma (9.6%). There were 3 cases of secondary tumors - one of renal cell carcinoma and the other two were adenocarcinomas of unknown primary. Conclusion: Malignant bone tumours form an important group of neoplastic lesions during the period of active growth spurt in adolescents and young adults. Adequate sampling of histopathological specimen with analysis of clinical details and radiological pictures can help in diagnosing the lesion with certainty.

Keywords: Malignant Bone Tumours; Osteosarcoma; Ewing’s Sarcoma; Chondrosarcoma.