Concomitant existence of giant epidural supra and infratentorial metastatic osteosarcoma.

Osteosarcomas are the most common malignant primary bone tumors in children and adolescents. Osteosarcomas metastasize to brain very rarely and they usually appear late in the disease process following metastasis to lung. Our case was a 43-year-old man who was admitted to the hospital with the complaint of imbalance for over a week. Physical examination revealed a bony mass over the left tibia. Cranial MRI and CT demonstrated a giant epidural infra and supratentorial mass (Figure 1A-C). Thoracal CT and bone scintigraphy demonstrated a mass in the lung and multiple skeletal mestastases respectively. We performed a biopsy through a burr-hole placed in the occipital bone. Pathological evaluation of the epidural mass was consistent with the diagnosis of osteosarcoma and the patient was transferred to the oncology unit. Menasa et al. reported an isolated brain metastasis of osteosarcoma in a patient with a patent foramen ovale (3). Chang et al. described a case that presented with an multiple subdural and epidural drop metastasis of osteosarcoma (1). Likewise, Hettmer et al., described the appearance of cerebellar and hemispheric parenchymal lesions in a 16-year-old boy who was previously diagnosed with osteosarcoma in the left proximal tibia (2). However, our case is the first patient in the literature harbouring giant infra and supratentorial epidural metastasis of metastatic osteosarcoma. In conclusion, osteosarcomas may present as giant epidural masses and a primary cancer diagnosis could be established through a biopsy from metastatic epidural masses.