The "caterpillar sign": a novel endoscopic indicator of eosinophilic esophagitis.

Background: Although several endoscopic findings of eosinophilic esophagitis (EoE), such as the EoE endoscopic reference score (EREFS), have been reported thus far, these endoscopic findings exhibit low specificity. Furthermore, most of these endoscopic findings were evaluated solely in patients from Western nations. We have recently noted a fragile, protruded mucosal lesion sandwiched between longitudinal furrows (similar to caterpillar tracks) on the esophagus in patients with EoE. We have termed this novel finding the "caterpillar sign". This study evaluated the clinical significance of the caterpillar sign and the EREFS for diagnosis of EoE in Japanese patients.

Methods: We retrospectively analyzed endoscopic images from 165 consecutive patients who underwent tissue collection on suspicion of EoE. We compared the clinical significance between the EREFS and the caterpillar sign. We defined EoE as the presence of ≥ 15 eosinophils on esophageal mucosa per high-power field; control images had < 15 eosinophils per high-power field. For evaluation of endoscopic diagnosis capacity using the total EREFS, 2 points was set as the cutoff value. The presence or absence of the caterpillar sign was evaluated.

Results: The sensitivity, specificity, positive predictive value, and negative predictive value of total EREFS ≥ 2 for the diagnosis of EoE were 100%, 56.2%, 56.6%, and 100%; for the caterpillar sign, those values were 83.3%, 98.1%, 96.2%, and 91.2%, respectively. Interobserver agreement for identification of the caterpillar sign was substantial (κ = 0.80) CONCLUSIONS: The caterpillar sign could be a novel reliable indicator for endoscopic diagnosis of EoE.