Diagnosis of primary osteosarcoma of the urinary bladder in a resource-limited setting: a case report and review of the literature.

Extraskeletal osteosarcoma is a rare malignant mesenchymal soft tissue tumor without attachment to the bone and is able to produce osteoid or cartilaginous matrix. Rendering a definitive diagnosis may pose a challenge particularly in a resource-limited setting. We report a case of primary osteosarcoma of the urinary bladder presenting with hematuria, dysuria and positive history of schistosomal contact. Computed tomography intravenous urogram revealed a large heterogeneous mass at the right superolateral aspect of the urinary bladder. Morphological evaluation of the biopsy and a minimal panel of immunohistochemical antibodies of vimentin and cytokeratin 20 ruled out potential differentials and thus confirmed the diagnosis of osteosarcoma.