P120 | Tumourlets and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia: a rare cause of Cushing syndrome

D. Piazza, M. Parisotto, M. Parolin, A. Uliana, A. Lo Nigro, V. Benetton | Ospedale Ca’ Foncello, Treviso, Italy

Premises: Approximately 15–20% of cases of Cushing’s syndrome are caused by ectopic adrenocorticotrophic hormone (ACTH) secretion, most often due to carcinoma of the lung. Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an unusual disorder in which there is nodular proliferation of airway neuroendocrine cells, a very rare but recognised cause of ectopic ACTH production.
Description of the Case report: A 65-year-old men, during hospitalization for myocardial infarction, presented clinical features of Cushing’s syndrome, biochemically confirmed by elevated levels of cortisol and ACTH. Pituitary MRI was normal, high dose dexamethasone suppression test showed a lack of suppression of cortisol and ACTH, suggesting an ectopic etiology. Chest CT revealed a subcentimetric pulmonary node located in the left lower lobe resulted in slight increase at follow-ups (from 3 vs. 8 mm). The patient underwent a pulmonary wedge resection and the histological examination showed the precence of pulmonary tumourlets on a background of DIPNECH.
Conclusions: DIPNECH/pulmonary tumourlets is a rare finding. However, in patients with ectopic ACTH secretion and no other obvious source, it should be considered. Although histopathology is required for the definitive diagnosis, HRCT can play an important role in the investigation of such patients. In the appropriate clinical context, the detection of pulmonary nodules and mosaicism with air trapping is highly suggestive of the diagnosis.