Leiomyosarcoma in bone: primary or secondary? A case report and review of the literature

Our case demonstrates how metastases may be present and symptomatic long before they produce sufficient osseous changes to render the lesions radiologically detectable. A case of leiomyosarcoma arising in the uterus and initially presenting as a femoral lesion is presented. It required an intensive review of the case history and of the previous pathology in order to identify the primary site in the uterus. In the literature nine cases of metastatic leiomyosarcoma presenting initially in bone are reviewed. Ten additional cases from the literature showed bone metastases as the first site of recurrence. When this is assessed together with some 14 cases of primary leiomyosarcomas reported arising in bone, one is impressed that this is an uncommon tumour in bone either as a primary or secondary. In all patients in whom a leiomyosarcoma is histologically proven in bone, all primary sites should be specifically and categorically excluded before the lesion is accepted as an osseous primary. This should include special stains for myofibrils and electron microscopy if at all possible, in order to differentiate such tumours from other sarcomas such as fibrosarcoma. This applies especially to patients with uterine lesions that have been previously treated, even if they have been regarded as benign initially. All previous pathology and in particular hysterectomy specimens should be carefully reviewed. The need to specifically identify a leiomyosarcoma as a primary lies in the different modalities of treatment used: aggressive ablative surgery for primary lesions as opposed to radiation and chemotherapy for metastatic disease.