Castleman Disease Masquerading as the Posterior Mediastinal Mass on 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography.

A 28-year-old female presented with an incidentally detected mediastinal mass, found on routine chest X-ray. 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) was advised to plan course of further management. FDG-PET/CT findings were suggestive of an FDG-avid soft-tissue mass in the left posterior mediastinum in paravertebral location with left pleural effusion. Overall, PET/CT scan findings favored the possibility of a nerve sheath tumor. However, histopathology along with immunohistochemistry confirmed the diagnosis of Castleman disease.