Osteosarcoma is a malignant bone tumor with an incidence of 1–3 cases per million people annually. While it can occur at any age but is most common in children and adolescents, with a secondary, lower incidence peak in individuals over 60 years.We present a clinical case of a 65-year-old female initially treated forosteomyelitis before being diagnosed with osteosarcoma of the humerus. The diagnosis was confirmed using radiological methods, including X-ray, ultrasound, computed tomography, and magnetic resonance imaging.Osteosarcoma in adults accounts forapproximately 1% of all cases, highlighting diagnostic challenges due to its rarity and nonspecific symptoms mimicking osteomyelitis. Therefore, osteosarcoma should be considered a primary differential diagnosis in such cases until proven otherwise. Keywords:osteosarcoma,humeral osteosarcoma,osteomyelitis,adult osteosarcoma, radiology.
Lyudmila Spichak (Mon,) studied this question.