[A 74-year-old female patient with histologically proven carcinoid of the lungs and pulmonary mosaic pattern].

Diffuse idiopathic neuroendocrine cell hyperplasia (DIPNECH) can be idiopathic or reactive to chronic airway disease, then termed pulmonary neuroendocrine cell hyperplasia (PNECH). DIPNECH can be complicated by obliterative bronchiolitis and is presumably often misdiagnosed because the clinical symptoms are unspecific, the entity is relatively unknown and high-resolution computed tomography (HRCT) in inspiration and expiration is necessary for the diagnosis. However, the HRCT findings of air-trapping in combination with nodules are very characteristic and should raise suspicion of this entity. DIPNECH is thought to be a precursor of tumorlets and carcinoids and usually runs a benign course. The diagnosis is confirmed by histology.