Differential diagnosis of Codman’s triangle: about a malignant tumor

Codman’s triangle is a periosteal reaction that may indicate the presence of a malignant tumor, being osteosarcoma and Ewing's sarcoma the most frequently associated. We present the case of an adolescent black woman who was diagnosed with a probable malignant tumor in the presence of a Codman triangle on femur radiography, subsequently confirming the presence of an osteosarcoma by biopsy. It is essential for the pediatrician to know how to recognize suspicious findings of malignancy on radiography in order to make an adequate diagnosis, which can reduce the morbidity and mortality associated with certain pathologies or neoplasms.