Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia and Granulomatous Inflammation Mimicking High-Grade Malignancy on FDG-PET/CT.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare form of preinvasive lung lesion associated with indolent carcinoid tumor formation. This disease is characterized by multiple small pulmonary nodules with low SUVmax on F-FDG PET. Biopsy and immunohistochemical staining for neuroendocrine markers confirm diagnosis. There is no consensus for treatment, which typically involves surgical excision or management of symptoms with steroid-based therapies. We report an unusual case of DIPNECH colocalizing with necrotizing granulomatous inflammation mimicking high-grade aggressive malignancy on FDG-PET and a typical case of DIPNECH for comparison with low FDG avidity.