Abnormal pulmonary bombesin immunoreactive cells in Wilson-Mikity syndrome (pulmonary dysmaturity) and bronchopulmonary dysplasia.

Wilson-Mikity syndrome (WMS) is a disorder of uncertain origin. It is sometimes considered a variant of bronchopulmonary dysplasia (BPD), but it lacks the characteristic microscopic stigmata of destruction and fibrosis caused by the barotrauma and oxygen toxicity of ventilator support. Conventional clinical and autopsy studies of WMS have failed to identify the underlying pathophysiology. This study evaluated bombesin-containing pulmonary neuroendocrine (PNE) cells in eight WMS cases, seven cases of BPD, and five controls, using the immunoperoxidase technique. The PNE cells were quantified by established morphometric techniques. The percentage of airways containing PNE cells in WMS (mean, 85.56%) was similar to that in the controls (mean, 82.6%) but significantly greater than that in BPD (mean, 21.28%) (p < .001). Measurement of intraepithelial PNE cell cytoplasm within the bombesin-immunopositive airways demonstrated apparent PNE cell hyperplasia in both WMS and BPD. Prominent numbers of PNE cells were also present in the respiratory bronchioles and alveolar units in WMS. The increased PNE cells in WMS may reflect chronic hypoxia from hypoventilation and or autonomic dysfunction. The profile in BPD may reflect a similar pathophysiology but complicated by ventilator-induced injury to airway epithelium.