The 2020 edition of WHO classification of bone tumours includes a group of “other mesenchymal tumours of the bone” which has been expanded to include tumours that were considered myogenic previously like leiomyosarcoma with deletion of primary leiomyoma of the bone. Primary bone leiomyosarcoma is a very rare bone tumour posing significant diagnostic challenge because of its rarity and morphological diversity. There are two important prerequisites for establishing a diagnosis of primary bone leiomyosarcoma, which includes exclusion of a soft tissue tumour extending into the bone and metastasis from other sites. Radiographically they present as ill-defined aggressive osteolytic lesions with a permeative pattern of bone destruction without any tumour matrix with marked longitudinal spread which is reminiscent of lymphomatous involvement of the bone. Primary leiomyosarcoma of the bone lacks any specific imaging manifestations and is often difficult to differentiate from other aggressive primary bone tumours. Most of the tumours in the long bones involve the metaphysis with extension into the epiphysis and the diaphysis. Immunohistochemistry is essential in diagnosing a primary bone leiomyosarcoma with smooth muscle actin having the highest sensitivity and specificity.