Extraskeletal osteosarcoma in the back

A 41-year-old woman visited our plastic surgeon with complaints of a progressively enlarged lower backmass for months. The mass had become very tender recently. Her physical examination demonstrated a round, movable, solid mass over the lower back, about 8 cm 7 cm at its largest diameter (Fig. 1A). The tumor was excised and the mass had no attachment to bone or periosteum. The specimen included a grayish white calcified tumor and a 9 cm 6-cm piece of attached skin (Fig.1B). On histological section, the tumor showed a central 3 cm 1.5 cm 1.5 cm polycystic space