Answer: Black hairy tongue

Histology: The lesion is characterized by marked elongation and hyperparakeratosis of degenerating filiform papillae. The papillary projections are blanketed by colonies of bacterial organisms.

Discussion: Hairy tongue (Black Hairy Tongue) is a condition related to abnormal kertatin clearance due to some combination of increased keratin production or decreased keratin desquamation from the filiform papillae. It consistently involves the dorsal tongue, sparing its lateral and anterior borders. The elongated papillae impart a hair-like appearance clinically. The “hairs” usually have a brown/black discoloration due to tobacco staining or the accumulation of bacteria. The lesion is confused with “hairy leukoplakia” in name alone. This confusion in terminology is to be avoided as hairy leukoplakia is an EBV-driven process involving the lateral border of the tongue that affects HIV-positive individuals. Unlike true squamous papillomas, the prominent papillary projections of Hairy tongue are comprised of mostly of hyperkeratotic debris without well developed fibrovascular cores. HPV is not present, and koilocytosis is not evident.

Hairy tongue is an entirely benign process, but one that may be aesthetically unpleasing and associated with halitosis. Treatment primarily centers on smoking cessation, meticulous oral hygiene, and desquamation of the hyperkeratotic papillae (e.g. brushing or scraping).