Abstract
Osteosarcoma (OS) is the most prevalent bone neoplasm of mesenchymal origin, accounting for 20% of all bone tumors worldwide. It mainly affects the marrow of long bones, and its diagnosis is more common among adolescents and the geriatric population. Histologically, it is characterized by high cellular variability, abundant osteoid and fibrotic material. In the early stages, it presents with only local symptoms such as pain, edema and limited joint mobility. This neoplasm, when detected promptly, is associated with a favorable prognosis and can be effectively treated through surgical removal and adjuvant therapy. The development of tumors in pregnant women is rare, and the occurrence of osteosarcoma is even more exceptional, with only 10 cases documented in the literature. Given its rarity, the present study describes the case of a female patient with OS diagnosed in the first trimester of pregnancy, where the patient responded well to treatment, resulting in no adverse effects on the pregnancy outcome.