Black Hairy Tongue Observed During Esophagogastroduodenoscopy.

Black hairy tongue, also known as lingua villosa nigra, is a benign oral condition characterized by a dark discoloration and "hairy" appearance on the tongue's dorsal surface, resulting from elongated filiform papillae. This condition is associated with risk factors such as smoking, poor oral hygiene, and diabetes, which increase susceptibility to microbial colonization, particularly by Candida species. Although commonly diagnosed by visual inspection, black hairy tongue is infrequently observed during endoscopic procedures. We report a case of a 69-year-old Japanese man with poorly controlled type 2 diabetes (hemoglobin A1c of 9.7%) and a significant smoking history of 49 pack-years. During a routine esophagogastroduodenoscopy, a dark lesion was detected on the dorsal surface of the tongue. Detailed imaging and biopsy revealed elongated papillae with fungal hyphae, confirming a diagnosis of candidiasis. This case underscores the value of esophagogastroduodenoscopy and histopathological examination in diagnosing black hairy tongue and distinguishing it from other pigmented lesions. Recognizing black hairy tongue as a potential finding during endoscopy may aid in prompt diagnosis, especially in patients with predisposing factors like smoking and diabetes.