Periosteal desmoid tumor: A benign-appearing lesion manifesting as smooth metaphyseal scalloping of the femur on plain radiography

“Desmoid tumors,” also known as “aggressive fibromatosis,” are rare mesenchymal neoplasms characterized by a fibrotic texture. Despite their non-metastatic nature, these tumors can lead to significant morbidity and mortality due to their tendency to recur locally and involve nearby organs. When these tumors affect bone, they are referred to as desmoplastic fibromas. This case report involves a 26-year-old male who presented with pain and tenderness in the right popliteal fossa. Diagnostic imaging and histopathology confirmed the presence of a periosteal desmoid tumor. Desmoid tumors have an incidence of 2–4 cases per million annually, with a slight female predominance, and typically arise in the third and fourth decades of life. Younger patients tend to experience more aggressive forms of the disease with higher recurrence rates. Histologically, these tumors consist of uniform spindle cells and fibroblasts within a dense collagenous stroma and exhibit distinct immunohistochemical profiles. Imaging, including ultrasound, computed tomography, and particularly magnetic resonance imaging (MRI), plays a critical role in the evaluation of these tumors, with MRI being the preferred modality. Management strategies include observation for stable tumors and intervention for symptomatic cases, with a growing preference for conservative treatment approaches.