Multifocal Cholesterol Granulomas of the Thymus: A Case Report of Positron Emission Tomography- Positive Benign Tumor of the Anterior Mediastinum.

Cholesterol granulomas of the thymus are extremely rare benign entities. Herein, we describe a case of cholesterol granuloma in a 45-year-old man who presented with multifocal anterior mediastinal lesions on computed tomography (CT). Positron emission tomography (PET)-CT revealed increased fluorodeoxyglucose uptake, with a maximum standardized uptake value of 8.3. Diffusion-weighted magnetic resonance imaging (MRI) revealed extreme hypointensity. He underwent total thymectomy by median sternotomy for presumed multiple thymoma. On histopathological analysis, cholesterol granuloma of the thymus was confirmed, and the patient had an uneventful postoperative course without recurrence for 28 months. Cholesterol granuloma of the thymus is a PET-CT-positive benign tumor with unique histological findings. The MRI findings were indicative of hypocellularity associated with a benign entity, whereas the PET-CT findings corresponded to granulomatous inflammation. Therefore, concurrent use of PET-CT and MRI can be helpful in distinguishing between benign cholesterol granulomas and malignant anterior mediastinal tumors.