Stridor caused by a blue laryngeal mass in an infant: case report. We describe an infant who had inspiratory stridor that began a few weeks after birth. Flexible upper airway endoscopy while the infant was awake showed a large blue mass at the posterior glottis, above the esophageal inlet. The lesion was only visible upon crying or coughing; it was undetectable when we examined the infant in the supine position during spontaneous breathing and did not respond to systemic treatment with propranolol. Based upon these typical features, we established a diagnosis of pressuredependent postcricoid mass.