Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia: clinical characteristics and progression to carcinoid tumour

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is considered a preinvasive lesion that may progress to carcinoid tumour [1]. Histologically, it is marked by a proliferation of neuroendocrine cells that is confined to the basement membrane (neuroendocrine cell hyperplasia; NECH), and/or has invaded past the basement membrane (carcinoid tumourlet) [2]. Tumourlets equal to or larger than 5 mm are classified as carcinoid tumours. Per the World Health Organization 2021 criteria, DIPNECH can be pathological (based solely on characteristic histological features) or clinical (diagnosed per characteristic symptoms and imaging findings, e.g. respiratory symptoms, bilateral pulmonary nodules, mosaic attenuation on computed tomography (CT)) [2]. In contrast to some lung diseases or neoplasms that can cause secondary, reactive NECH/tumourlets to form, DIPNECH is marked by such hyperplasia without an identifiable cause. DIPNECH is a rare disease that is often misdiagnosed. In this study, it primarily affected elderly white women who were non-smokers. Lung nodules could slowly progress over years to carcinoid tumours. Average growth rate per nodule was 0.8 mm per year. https://bit.ly/3q1HD1k