Pleural desmoid tumor mimicking a myofibroblastic neoplasm: Imaging-pathologic correlation.

Desmoid tumors are rare, locally aggressive soft-tissue neoplasms that may present a diagnostic challenge due to overlapping imaging and histopathologic features with other myofibroblastic lesions. We report the case of a 41-year-old woman presenting with a 2-year history of right-sided chest pain and progressive numbness of the right upper extremity. Contrast-enhanced computed tomography (CT) demonstrated a large pleural-based mass with chest wall extension. Initial biopsy suggested an inflammatory myofibroblastic tumor; however, further characterization with magnetic resonance imaging (MRI) and subsequent surgical resection were performed. Definitive diagnosis was established by histopathologic and immunohistochemical analysis, confirming desmoid-type fibromatosis. Despite partial symptom improvement after surgery, follow-up imaging at 30 months demonstrated persistent soft-tissue involvement at the thoracic inlet with tumor progression, correlating with ongoing neurologic symptoms. This case highlights the importance of radiologic-pathologic correlation for accurate diagnosis and emphasizes the locally aggressive behavior and recurrence potential of pleural desmoid tumors, particularly when critical structures are involved.