Differentiation between carcinoid and sarcoid with F-18 FDG PET and In-111 pentetreotide

A patient who presented with weight loss and recurrent left lower lobe pneumonia was diagnosed with endobronchial carcinoid. Chest CT scan demonstrated extensive mediastinal and hilar lymphadenopathy suggesting stage IIIB disease, but radionuclide imaging with In-111 pentetreotide and F-18 FDG PET diagnosed 2 distinct pathologic processes based on functional differences between neuroendocrine tumors (expressing somatostatin receptors) and sarcoidosis (intensely FDG-avid). The possible association of carcinoid with sarcoidosis and sarcoid-like reactions in regional lymph nodes should always be considered, and the staging process should include both anatomic and functional imaging and biopsy confirmation of suspected metastatic lesions.