Imaging description

This 16-month-old girl presented with a year-long history of persistent cough and tachypnea. On physical examination she had sternal retractions and widespread crackles on auscultation. A chest radiograph (Fig. 13.1a) demonstrated bilateral overinflation and increased perihilar markings. A controlled ventilation inspiratory/expiratory low dose CT (Fig. 13.1b, c, d) was performed and showed perihilar and anterior (right middle lobe and lingula) ground glass opacity (GGO) as well as patchy lower lobe air trapping in expiration. On the basis of the CT appearance in conjunction with the clinical findings, the diagnosis of neuroendocrine cell hyperplasia of infancy (NEHI) was suggested. Infant pulmonary function tests confirmed the presence of an obstructive lung abnormality. Biopsy was considered unnecessary and the child was followed clinically and has been stable with slow improvement in clinical symptoms.

Importance

NEHI, also known as persistent tachypnea of infancy or chronic idiopathic bronchiolitis of infancy, is an idiopathic interstitial lung condition in infants. While the only definitive diagnostic test is lung biopsy that demonstrates prominent immunostaining with bombesin of an increased number of bronchiolar neuroendocrine cells, the CT appearance is typical in a high percentage of cases. The reason for the increased number of neuroendocrine cells is uncertain (perhaps a non-specific response to injury); these cells are known to mediate bronchiolar vasoconstriction. GGO distributed in the lingula, right middle lobe, and perihilar regions along with mosaic perfusion and air trapping are the most characteristic CT findings (Fig. 13.1). This CT appearance has been shown to be approximately 78% sensitive and 100% specific for NEHI. CT findings are atypical and non-diagnostic in approximately 20% of cases. Correct diagnosis has both prognostic and therapeutic implications.