PMC8077363_01
Coronal (a) and axial (b) CT of the abdomen in a 10-year-old girl with a primary osteosarcoma of the distal femur. The abdominal mass presented 6 months after completion of chemotherapy. Subsequent biopsy confirmed the diagnosis of osteosarcoma metastasis to the peritoneal cavity. CT, computed tomography.
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F1
The abdominal CT demonstrated a large left lower quadrant mass (13 x 11 x 10 cm) with mineralization, a smaller adjacent mass, multiple masses throughout the abdominal cavity, and ascites (Fig. 1).
PMC8077363_02
a, b Coronal (a) and axial (b) CT of the abdomen and pelvis in a 45-year-old man with metastatic osteosarcoma to the lungs, abdomen, and retroperitoneal space. Note the large volume of ascites, prominent enhancement of the peritoneal surfaces, and omental caking. Nodular lesions could be seen in the liver, adrenal gland, and pericolonic gutters. c The patient's thigh resection specimen demonstrated a high-grade malignant osteoid-producing neoplasm, consistent with conventional osteosarcoma with both fibroblastic and osteoblastic features. H&E stain, x20. d A biopsy of the colon at the hepatic flexure showed malignant cells within the lamina propria with similar morphology to the original specimen. H&E stain, x20. There was no overlapping epithelial dysplasia or keratin expression within the cells, arguing against a new colorectal primary. Biopsy of an omental nodule showed similar histologic features. CT, computed tomography.
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F2
It revealed peritoneal thickening, ascites, small bowel obstruction, omental stippling, hepatic lesions, and bilateral adrenal nodules (Fig. 2a, b).