Clinical characteristics and cytological changes in mucinous obstruction diagnosed by dacryoendoscopy.

To analyze the clinical characteristics of mucinous obstruction diagnosed by dacryoendoscopy and compared the cytological changes with membranous obstruction using a modified liquid-based thin prep cytology method. A retrospective chart review was conducted on 53 eyes of 51 patients with mucus obstruction based on dacryoendoscopic findings from January 2022 to October 2022. Liquid-based thin-prep cytology was performed by irrigating the inside of the nasolacrimal drainage system with saline during dacryoendoscopy-guided silicone tube intubation. Pathological findings were analyzed through a comparison of mucinous obstruction with membranous obstruction as determined by dacryoendoscopic findings. The modified liquid-based thin prep cytology technique had a higher cytology detection rate across all cases. Mucinous obstruction exhibited a significantly higher number of successful canalicular irrigation test cases compared to membranous obstruction. In mucinous obstruction, epithelial squamous cells were more frequently detected in pre-sac obstruction, whereas columnar epithelial cells were predominant in post-sac obstruction. Inflammatory cells showed a stronger correlation with primary change and post-sac obstruction. Bacterial colonies were observed exclusively in cases of mucinous obstruction. The use of a modified liquid-based thin prep cytology method enables the examination of histopathological changes in the lacrimal passage in primary acquired nasolacrimal duct obstruction (PANDO), particularly in cases of mucinous obstruction, without the need for invasive biopsies. These findings enhance the understanding of the etiopathogenesis of mucinous obstruction, complementing knowledge of membranous obstruction in PANDO.