Imaging findings in pseudocyst osteosarcoma

OBJECTIVE. Our purpose was to describe four female patients with osteosarco ma whose clinical and imaging findings primarily suggested either simple or aneurysmal bone cyst. All lesions were osteolytic, intracompartmental, and expanded bone without periosteal reaction. None of the patients presented during the peak age incidence for osteosarcoma. From imaging to histologic diagnosis, the discovery of osteosarcoma ranged from 1 week to 3 years. CONCLUSION. Atypical osteosarcoma may rarely mimic simple or aneurysmal bon e cyst radiologically and may show a nonmalignant rate of growth. It may be more frequently encountered in females and may not present during the peak age incidence for osteosarcoma, Microscopically, the tumors were not cysti c, necrotic, or telangiectatic but were conventional osteosarcoma and osteo clast-rich osteosarcoma.