[Extraskeletal osteosarcoma in the gallbladder].

Extraskeletal osteosarcoma is a rare malignant soft tissue tumor. Authors present the history of a 61-year-old woman who had bone like tissue in her gallbladder at cholecystectomy. Histology proved, it was extraskeletal osteosarcoma of the gallbladder. Such disease has not been previously reported in the literature. She developed metastatic disease five months after the operation: multiplex cystic-calcified metastases appeared in the abdominal wall and in the peritoneal cavity. We present pathology findings, including ultrastructural features.