Fetus with a large buttock mass on prenatal ultrasound Pediatric Imaging Surgical-Pathological-Clinical May 6, 2023April 25, 2023 Postmortem open (left) and sagittally sectioned (right) gross pathological images show the extent of the intrapelvic extension of the massive tumor arising from the sacrococcygeal region. The diagnosis was sacrococcygeal teratoma. Related Published May 6, 2023April 25, 2023