Incidental Detection of Poorly Differentiated Carcinoma of the Left Lacrimal Sac During Dacryocystorhinostomy: A Case Report

Background: Tumors of the lacrimal sac are rare and often mimic benign inflammatory conditions such as chronic dacryocystitis. Malignant lesions may remain undiagnosed until advanced stages. Case Presentation: We report the case of a 67-year-old female with no significant medical history, who presented with chronic left-sided epiphora since December 2022, associated with episodes of secondary infection. In 2023, probing of the lacrimal system revealed complete obstruction of the left lacrimal drainage pathway. A CT-dacryocystography confirmed the absence of opacification of the left lacrimal sac and nasolacrimal duct. A dacryocystorhinostomy was performed with BIKA stent placement. Systematic intraoperative biopsies unexpectedly revealed a poorly differentiated carcinoma of the lacrimal sac. Conclusion: This case underscores the value of routine biopsy during DCR, particularly in chronic or atypical cases. Early diagnosis of rare but aggressive tumors can significantly impact patient management and prognosis.