BACKGROUND Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare pulmonary disorder that is characterized by diffuse hyperplasia of bronchiolar and bronchial pulmonary neuroendocrine cells. In this condition, when no other pathological pulmonary condition is detected, DIPNECH is considered to be an idiopathic lung disease. DIPNECH is a rare condition that can be difficult to distinguish from other forms of reactive pulmonary neuroendocrine cell hyperplasia (NECH). We present a case of DIPNECH and describe the approach to diagnosis of this rare condition. CASE REPORT A 69-year-old woman with a past medical history of successfully treated lobular carcinoma of the breast, presented to our department with a respiratory tract infection. High-resolution computed tomography (HRCT) of the chest showed a suspicious pulmonary nodule, measuring 13 mm, in the right middle pulmonary lobe. Combined positron emission tomography (PET) and computed tomography (CT), showed a solid and metabolically active nodule. A transbronchial biopsy and histopathology confirmed a diagnosis of DIPNECH. CONCLUSIONS It is possible that DIPNECH is an under-diagnosed pulmonary condition because it is rarely associated with symptoms. At this time, there are no evidence-based management guidelines. While the majority of cases have stable clinical course, some cases can progress to cause airway obstruction. This case report highlights this rare, but potentially progressive condition, and the need for evidence-based management guidelines for DIPNECH.