Rare Presentation of Inflammatory Lung Disease and Subcutaneous Nodules on FDG PET/CT Scan: Brief Discussion of Differential Diagnoses.

We present a 37-year-old man with cough and progressive dyspnea for the past 3 years. According to inconclusive chest CT scan and lung biopsy histopathology findings, the patient referred for 18F-FDG PET/CT scan for further evaluation. Classic pulmonary manifestations of Langerhans cell histiocytosis were seen on CT images with intense FDG uptake on PET scan. Moreover, PET/CT revealed multiple hypermetabolic subcutaneous foci throughout his body. Finally, the patient was treated with corticosteroids. Follow-up chest CT images demonstrated improvement of lung lesions in accordance with improvement in the patient's symptoms. We are briefly discussing differential diagnoses in this patient.