Tailored Surgical Management for Maxillary Sinus Fungus Ball‐Induced Nasolacrimal Duct Obstruction: A Case Series and Literature Review

ABSTRACT Maxillary sinus fungus ball (MSFB)‐induced nasolacrimal duct obstruction (NDO) is extremely rare, with nonspecific symptoms posing diagnostic and therapeutic challenges. Long‐term MSFB causes nasolacrimal duct bone erosion via chronic inflammation‐driven cytokine release and pressure necrosis, often leading to irreversible obstruction when the extent of bone destruction is extensive. We analysed two cases of MSFB‐induced NDO (61‐year‐old female, 71‐year‐old male) with prolonged epiphora (20–24 months), CT‐documented bone erosion and intraoperative severe fibrotic scarring, treated successfully with combined functional endoscopic sinus surgery (FESS) and dacryocystorhinostomy (DCR). A literature review identified two cases managed with FESS alone due to reversible NDO. This study proposes pre‐ and intraoperative criteria for distinguishing irreversible NDO, highlighting that individualised surgical strategies tailored to irreversible NDO resulting from extensive MSFB‐induced bone destruction are essential. Such strategies, either FESS alone or combined with DCR based on comprehensive evaluation, effectively address the aetiology and functional sequelae of MSFB‐related NDO.