Neuroendocrine cell hyperplasia as an unusual form of interstitial lung disease.

STUDY OBJECTIVES

Two patients diagnosed with interstitial lung disease (ILD) secondary to pulmonary neuroendocrine cell (PNEC) hyperplasia are presented.

BACKGROUND

Pulmonary neuroendocrine cell hyperplasia (PNECH) is a rare entity worldwide and few cases presenting as ILD have been reported. Following the consensus criteria established by the American Thoracic Society (ATS) and the European Respiratory Society (ERS), three patients from among 500 ILD patients over the last 10 years in our institution were diagnosed with PNECH. The diagnosis was established by open lung biopsy using specific stains to demonstrate neuroendocrine cells in lung tissue.

METHODS

Patients were questioned on their medical and pathological history, occupational or environmental exposure to toxic substances and any relationship with smoking. In addition, were recorded symptoms at presentation, physical signs, analytic and respiratory function results, chest X-ray and CT scan features, bronchoscopy findings including bronchoalveolar lavage and transbronchial biopsy, and open lung biopsy findings.

RESULTS

In these two patients, PNECH was the only cause of their diffuse lung disease. Clinical signs and symptoms (cough, expectoration and progressive dyspnea) were similar to other idiopathic interstitial pneumonias and radiologic features (ground-glass infiltrates in mosaic pattern) were consistent with those of non-specific interstitial pneumonia or the onset of hypersensitivity pneumonitis. Functional respiratory alterations were consistent with restrictive pattern. Transbronchial and open biopsy findings are described, as well as the treatment and course of the disease. The two patients had a favorable outcome.

CONCLUSIONS

Two cases of ILD secondary to PNEC hyperplasia are presented, with clinical and radiological findings that might be mistaken for other types of idiopathic interstitial pneumonias. The disease course is described and the possible etiopathogenic role that PNECs might play in the development of lung fibrosis is discussed.