Myeloid sarcoma of the posterior mediastinum mimicking lymphoma: Potential role of dual-energy CT.

Myeloid sarcoma is a rare extramedullary malignant tumor composed of immature myeloid cells and is frequently associated with acute myeloid leukemia. Isolated mediastinal involvement is exceedingly uncommon and often poses a significant diagnostic challenge because of nonspecific clinical and imaging features, frequently leading to misdiagnosis as lymphoma. We report posterior mediastinal myeloid sarcoma in a 39-year-old man who presented with back pain and chest discomfort. Conventional contrast-enhanced computed tomography demonstrated a homogeneous posterior mediastinal soft-tissue mass encasing the descending aorta, and lymphoma was initially suspected. Contrast-enhanced dual-energy computed tomography demonstrated low iodine uptake and a relatively flat spectral attenuation curve, providing supplementary information for lesion characterization and imaging-pathology correlation. The final diagnosis was established after surgical resection by histopathological and immunohistochemical examination. This case suggests that dual-energy computed tomography may be a useful adjunctive imaging tool in selected mediastinal tumors; however, its findings should be interpreted cautiously and cannot replace histopathological, immunohistochemical, and hematological evaluation.