Immunohistochemical Detection of Pepsin in Laryngeal Mucosa for Diagnosing Laryngopharyngeal Reflux

Objectives/Hypothesis: To investigate whether the pepsin immunohistochemical (IHC) staining of the laryngeal mucosa epithelia is an available test for diagnosing laryngopharyngeal reflux (LPR) in clinic. Study Design: Prospective case series. Methods: Biopsy specimens from interarytenoid mucosa of LPR patients (seven acid LPR and eight nonacid LPR) and 21 sex- and age-matched normal controls were obtained for pepsin IHC staining. The diagnosis of LPR was based on 24-hour combined multichannel intraluminal esophageal impedance pH monitoring. The results of IHC staining were semiquantitatively analyzed and scored as negative (-), weakly positive (+), moderately positive (++), and strongly positive (+++). Results: Six of seven acid LPR (85.7%) and six of eight nonacid LPR (75%) mucosa samples were moderate to strongly positive for intracellular pepsin. By contrast, only three of 21 normal controls (14.3%) were moderately positive. The difference in intracellular pepsin between LPR and the normal laryngeal mucosa was statistically significant (P < .01). No significant difference in intracellular pepsin was observed between the acid and nonacid LPR mucosal samples (P = .453). Using weak positivity (+) as a cutpoint, the presence of intracellular pepsin in the laryngeal mucosa had a sensitivity of 100% and a specificity of 47.6% in detecting LPR (P < .05). However, using the moderate positivity (++) as the cutpoint, the pepsin had a slightly decreased sensitivity of 80% but a sharply increased specificity of 85.7% (P < .05) in the detection of LPR. Conclusions: Pepsin IHC staining of the laryngeal mucosa appears to be a sensitive and specific test for diagnosing LPR in a clinical application.