Hairy tongue is characterized by
**Core Concept**
Hairy tongue is a benign condition characterized by an abnormal elongation and darkening of the filiform papillae on the tongue surface. This condition is often associated with an imbalance in the normal flora and an accumulation of keratin debris.
**Why the Correct Answer is Right**
The correct answer is related to the accumulation of keratin debris, which leads to an abnormal appearance of the tongue. The filiform papillae on the tongue surface are responsible for the sensation of texture and taste. In hairy tongue, these papillae become overgrown and accumulate keratin debris, giving the tongue a hairy appearance. This condition is often seen in individuals who use tobacco products, have poor oral hygiene, or consume a diet high in roughage.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because hairy tongue is not primarily caused by an increase in the number of taste buds. While taste buds are present on the tongue, they are not responsible for the hairy appearance.
* **Option B:** This option is incorrect because hairy tongue is not a symptom of esophageal cancer. While some oral conditions can be a risk factor for esophageal cancer, hairy tongue is not a direct symptom of the disease.
* **Option C:** This option is incorrect because hairy tongue is not a sign of tongue cancer. While some oral conditions can be a risk factor for oral cancer, hairy tongue is a benign condition.
**Clinical Pearl / High-Yield Fact**
Hairy tongue is often associated with poor oral hygiene and an imbalance in the normal flora of the mouth. Regular brushing and flossing can help prevent this condition.
**Correct Answer: D. Accumulation of keratin debris**