Pulmonary spirometry was compatible with significant upper airway obstruction. A fiberoptic evaluation of the upper airway showed no significant findings. A chest CT scan demonstrated a round, partially obstructing, space-occupying lesion in the lower third of the trachea (Fig 1
, top left, a). No other focal findings were detected in the lungs. Flexible foberoptic bronchoscopy (FOB) was performed. At the lower third of the trachea, a round, smooth lesion was found with the obstruction of 80% of the tracheal lumen (Fig 1, top right, b). A biopsy specimen from the lesion was compatible with Langerhans cell histiocytosis, and therefore a second FOB was performed with full excision of the lesion using laser therapy with a Nd-YAG laser (30 W; total energy, 3,000 J). The mass rapidly “melted” in response to laser therapy and was easily removable with FOB forceps. Equipment for the performance of rigid bronchoscopy was available on hand if required. A histologic evaluation of the specimen demonstrated the mixed infiltration of lymphocytes, plasma cells, and eosinophils, with aggregates of Langerhans cells (Fig 1, bottom left, c). Immunohistochemical staining was strongly positive for S-100 protein (Fig 1, bottom right, d), was weakly positive for CD1a, and was negative for CD30 and CD68. The histologic findings were considered to be diagnostic of Langerhans cell histiocytosis with reparative changes. Following excision of the lesion, an immediate dramatic improvement in the patient’s symptoms was noted. Two months later, she was completely asymptomatic, with normalization of pulmonary function. A follow-up FOB showed only a small endotracheal scar at the site of the excised mass.