Primary Osteosarcoma of Testis and Para-Testicular Tissues: A Review and Update of the Literature

Osteosarcoma of the testis and para-testicular tissue is a terminology that refers to a malignant tumor that contains pure osteoid forming malignant cells with no skeletal origin that affect the testis or para-testicular tissues. These tumors tends to present as an intra-scrotal or testicular mass which is non-specific. It may also present in association with a hydrocele. Clinical examination may reveal a firm to hard mass in the testis or in the affected para-testicular tissue. The inguinal glands may be normal but on rare occasions there may be lymph node enlargement in advanced cases. If there is an associated hydrocele there may be clinical examination evidence of a hydrocele. The full blood count, serum urea and electrolytes and liver function tests would tend to normal unless there are un-related pathologies which would need to be investigated accordingly. Nevertheless, if there are multiple liver metastases the liver function test results may show derangement in one or more elements of the liver function tests. The serum Beta Human Chorionic gonadotrophin, alpha fetoprotein, and lactate dehydrogenase levels would tend to normal unless the osteosarcoma is associated with a synchronous Germ cell tumor which does happen occasionally. Radiology imaging could show evidence of a heterogeneous mass within the testis in the case of a testicular tumor or in an intra-scrotal area at the site of the lesion and the mass tends to be associated with calcification. Treatment tends to be radical orchidectomy for localized tumors involving the testis only, but para-testicular osteosarcomas tend to be treated by radical orchidectomy plus en bloc excision of the para-testicular tissue. If there is evidence of metastasis then adjuvant therapy can be given. Gross examination of specimens of an excised osteosarcoma of the testis would tend to show a well-circumscribed, firm, solid, whitish tan, expansile mass which had compressed the surrounding parenchyma of the testis. Microscopic examination of primary osteosarcoma of the testis specimen would tend to show sheets of pleomorphic round to spindle cells that contain prominent nucleoli, areas of osteoid and scattered areas of mineralization, high mitotic activity and atypical mitosis, osteoid and at times osteoclasts among the area of osteoid. Immunohistochemistry studies of osteosarcoma of the testis or any para-testicular structures would tend to show the tumor cells stain positively for vimentin, but the tumor cells would stain negatively for: smooth muscle actin, CD34, cytokeratin, desmin, inhibin, myo-D1, and S-100 proteins.