Primary extraskeletal osteosarcoma of sigmoid mesocolon: a case report and a review of the literature

Xinyang Nie,Weidong Li,Chuan Li,Weihua Fu,Li Lu

doi:10.1186/s12957-021-02337-9

Abstract

BackgroundExtraskeletal osteosarcoma (ESOS) is a rare mesenchymal malignancy, which produces osteoid, bone, or chondroid material and is located in the soft tissue without attachment to skeletal bones and periosteum. One of the things that ESOS originated from mesentery is much rarer.Case presentationA 75-year female had a history of pain in the left lower abdomen for more than 4 months. Abdominal computerized tomography (CT) and magnetic resonance imaging revealed a large, irregular, and solid-cystic mass (largest diameter was 11.5 cm). The tumor was radically removed during an open operation. It was composed of abundant osteoid and polyhedral-shaped tumor cells with high atypia and high mitotic activity microscopically. The final pathological diagnosis was osteoblastic osteosarcoma, arising from the sigmoid mesocolon with negative margins. A 9-month follow-up by CT exhibited signs of peritoneal metastasis.ConclusionsGiven the rarity of cases of mesenteric ESOS, diagnosis mainly depended on pathology findings or should be taken into consideration when the mesenteric mass was found. Its most effective treatment had not been determined, with surgical excision being generally accepted. Ensuring negative surgical margins may be an important factor affecting prognosis.

Highlights

Extraskeletal osteosarcoma (ESOS) is a rare mesenchymal malignancy, which produces osteoid, bone, or chondroid material and is located in the soft tissue without attachment to skeletal bones and periosteum
Given the rarity of cases of mesenteric ESOS, diagnosis mainly depended on pathology findings or should be taken into consideration when the mesenteric mass was found
In contrast to skeletal osteosarcoma, which always occurs in patients in the first three decades of life, most ESOS occurs in the fifth and seventh decades of life and at a mean reported age of 60 years [6, 8]

Summary

Conclusions

Extraskeletal osteosarcoma is a relatively uncommon soft tissue sarcoma, especially originating in the mesentery. ESOS growth in the abdominal cavity is relatively insidious, exhibiting typical clinical symptoms. The imaging features of ESOS are devoid of apparent characteristics. ESOS should be considered when imaging reveals intraperitoneal solid-cystic or calcified masses. There is no agreement on the most effective treatment, and surgical excision is widely accepted. Ensuring negative surgical margins may be an important factor affecting prognosis

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