Histopathology of the uvula and the soft palate in patients with mild, moderate, and severe obstructive sleep apnea

Objective: To study morphometric and qualitative histopathologic changes of the soft palate and uvula in patients with mild, moderate, and severe obstructive sleep apnea. Study Design: A prospective, nonrandomized controlled study. Methods: The distal soft palate and uvula were excised during uvulopalatopharyngoplasty from 34 male patients with obstructive sleep apnea. Control specimens were retrieved from 7 male cadavers with no related disorders. All specimens underwent routine processing and the mid-sagittal sections were studied. Morphometric analysis of the relative proportions of the tissue constituents was carried out. Also, a qualitative assessment was performed to detect possible pathologic changes. Results: The body mass index of patients was significantly higher from that of control subjects. The area fraction occupied by the tissue constituents of the distal portion of the soft palate and uvula in patients with mild, moderate, and severe obstructive sleep apnea and in control subjects was similar, with small and insignificant differences regarding the contents of glands, muscle, fat, blood vessels, and the epithelium. Only the connective tissue was significantly greater in patients with moderate obstructive sleep apnea than in those with severe obstructive sleep apnea and control subjects. The qualitative assessment of the specimens disclosed normal tissue architecture without evidence of destruction. Vascular engorgement, fibrosis, edema, inflammatory cell infiltration, and dilated glandular ducts were observed in a portion of patients and control subjects. Conclusions: The structure of the distal soft palate and uvula of patients with obstructive sleep apnea undergoes insignificant changes and is independent of the body mass index levels, indicating that the pathologic changes are probably the sequela of airway obstruction rather than its cause.