Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is recognized as a preneoplastic condition by the World Health Organization. We reviewed our experience with 30 patients and performed a systematic review of the English literature to collect best evidence on the clinical features and disease course in 169 additional patients. Some patients presented with one or more carcinoid tumors associated with multiple small pulmonary nodules on imaging studies and showed DIPNECH as a somewhat unexpected pathologic finding. Others presented with multiple small pulmonary nodules that raised suspicion of metastatic disease on imaging. A third subset was presented with previously unexplained respiratory symptoms. In most patients, DIPNECH was associated with a good prognosis, with chronological progression into a subsequent carcinoid tumor noted in only one patient and death attributed directly to DIPNECH in only two patients. There is no best evidence to support the use of octreotide, steroids, or bronchodilators in DIPNECH patients.
Keywords: Carcinoid tumor; DIPNECH; Diffuse idiopathic neuroendocrine cell hyperplasia; Preneoplasia; Tumorlet.