Real-time diagnosis of a lesion of the anal canal observed by endocytoscopy.

Anal canal cancer (ACC) is a rare yet noteworthy malignancy that is strongly associated with high-risk human papillomaviruses (HPVs). This case report highlights the diagnostic utility of endocytoscopy (EC) in distinguishing high-grade squamous intraepithelial lesions (HSILs) from low-grade lesions (LSILs) in a 57-year-old male presenting with hematochezia. Traditional magnifying endoscopy was inconclusive; however, EC provided detailed visualization of cellular and vascular changes, facilitating a diagnosis of HPV-associated HSIL or carcinoma in situ. Subsequent en bloc resection by endoscopic submucosal dissection was performed successfully, with no recurrence at the 6-month follow-up. This case underscores the value of EC in enhancing diagnostic accuracy for anal lesions, suggesting potential benefits for broader diagnostic applications.