Chest x-ray was normal. Pulmonary function tests are shown in table 1.

At review in August 2006 she remained breathless on exertion and her exercise tolerance had fallen to 100 yards. She was still coughing, producing white sputum, and had symptoms of gastro-oesophageal reflux. Her chest was clear to auscultation. Spirometry is shown in Table 1. Her eosinophil count was normal. At that point, a proton pump inhibitor was started as treatment for reflux and a high resolution CT scan was arranged to look for bronchiectasis or interstitial lung disease (figure 1). This was performed on 11 July 2006 and showed bilateral fine nodules. There was no evidence of bronchiectasis. When the images were reviewed by the radiologist they were thought to be most likely to be incidental, but recommended a repeat CT scan. In view of her minimal smoking history (<1 pack year in her teens), a 1-year follow-up scan was arranged. This was performed on 16 July 2007 and showed persistence of the nodules but with no interval change (figure 2). The differential diagnosis was thought to be wide but benign, given the stable size of the nodules over a 1-year period. At review in January 2008, her breathlessness was stable and on auscultation she had crackles and wheeze bilaterally. Full pulmonary function tests undertaken are shown in table 1. Anti-neutrophil cytoplasmic antibodies and antinuclear antibodies were negative and serum angiotensin-converting enzyme and calcium were normal. A provisional diagnosis of pulmonary sarcoidosis was made and the patient was referred for biopsy by video-assisted thoracoscopic surgery. This was undertaken on 28 February 2008.

DIPNECH is a rare condition. Forty-six cases have so far been reported in the literature.^{1 2 3} The majority have airways disease symptoms. It is known that reactive hyperplasia of neuroendocrine cells can occur in the setting of airways fibrosis and inflammation or as an adaptive response to hypoxia.^{4 5} In DIPNECH there is the presence of neuroendocrine cell hyperplasia with physiological evidence of airflow obstruction that is otherwise unexplained. In the 1999 WHO classification of lung tumours, DIPNECH was included as a pre-neoplastic lung lesion. In DIPNECH there is hyperplasia of neuroendocrine cells in the airways without invasion beyond the basement membrane. If the cells extend into the interstitium and are <5 mm, the lesion is classified as a carcinoid tumourlet. If >5 mm it is a carcinoid tumour.⁶ A retrospective study of surgical specimens undertaken in 2007 found that 28 of 294 patients with a carcinoid tumour or tumourlet had two or more lesions. In total, 93% of cases were women with a mean age of 65 years. Half of those with multiple nodules had respiratory symptoms. Only one patient had a clinical syndrome resembling DIPNECH.