Objective: Neuroendocrine cell hyperplasia of infancy (NEHI) is a form of childhood interstitial lung disease characterized by tachypnea, retractions, crackles, and hypoxia. The aim of this study was to report and discuss the clinical, imaging, and histopathological findings in a series of NEHI cases at a tertiary pediatric hospital, with an emphasis on diagnostic criteria and clinical outcomes. Methods: Between 2003 and 2011, 12 full-term infants were diagnosed with NEHI, based on clinical and tomographic findings. Those infants were followed for 1-91 months. Four infants were biopsied, and the histopathological specimens were stained with bombesin antibody. Results: In this case series, symptoms appeared at birth in 6 infants and by 3 months of age in the remaining 6. In all of the cases, NEHI was associated with acute respiratory infection. The most common initial chest HRCT findings were ground-glass opacities that were in the middle lobe/lingula in 12 patients and in other medullary areas in 10. Air trapping was the second most common finding, being observed in 7 patients. Follow-up HRCT scans (performed in 10 patients) revealed normal results in 1 patient and improvement in 9. The biopsy findings were nonspecific, and the staining was positive for bombesin in all samples. Confirmation of NEHI was primarily based on clinical and tomographic findings. Symptoms improved during the follow-up period (mean, 41 months). A clinical cure was achieved in 4 patients. Conclusions: In this sample of patients, the diagnosis of NEHI was made on the basis of the clinical and tomographic findings, independent of the lung biopsy results. Most of the patients showed clinical improvement and persistent tomographic changes during the follow-up period, regardless of the initial severity of the disease or type of treatment.Keywords: Lung diseases, interstitial/diagnosis; Lung diseases, interstitial/treatment; Tomography, X-ray computed. ResumoObjetivo: A hiperplasia de células neuroendócrinas do lactente (HCNEL) é uma forma de doença pulmonar intersticial da infância caracterizada por taquipneia, retrações, estertores e hipóxia. O objetivo deste estudo foi descrever e discutir os achados clínicos, histopatológicos e de imagem em uma série de casos de HCNEL em um hospital pediátrico terciário, enfatizando critérios de diagnóstico e desfechos clínicos. Métodos: Entre 2003 e 2011, 12 lactentes nascidos a termo foram diagnosticados com HCNEL, com base em critérios clínico-tomográficos e acompanhados por 1-91 meses. Quatro lactentes foram submetidos a biopsia pulmonar, e as amostras histopatológicas foram coradas com anticorpo para bombesina. Resultados: Nesta série de casos, os sintomas surgiram ao nascimento em 6 lactentes e em até 3 meses de idade nos outros 6. Em todos os casos, HCNEL estava associada com infecção respiratória aguda. Os achados iniciais em TCAR de tórax foram opacidades em vidro fosco em lobo médio e língula, em 12 pacientes, e em outras regiões medulares, em 10. O aprisionamento aéreo foi o segundo achad...