Differential Diagnosis for Discoloration at the Back of the Tongue

Single Most Likely Diagnosis

• Hairy Tongue: This condition is characterized by an abnormal elongation of papillae on the tongue surface, which can lead to discoloration, typically at the back of the tongue. It's often associated with poor oral hygiene, antibiotic use, or smoking.

Other Likely Diagnoses

• Oral Candidiasis (Thrush): A fungal infection that can cause white patches on the tongue, including the back, and is more common in immunocompromised individuals or those with poor oral hygiene.
• Tongue Pigmentation: Various factors such as smoking, certain medications, or nutritional deficiencies can lead to pigmentation changes on the tongue, including the back.
• Lichen Planus: An autoimmune condition that can affect the mucous membranes inside the mouth, leading to white, lacy patches or discoloration, including on the back of the tongue.

Do Not Miss Diagnoses

• Oral Cancer: Although less common, any unusual or unexplained discoloration, especially if accompanied by other symptoms like pain, difficulty swallowing, or a lump, should prompt consideration of oral cancer due to its potential severity and the importance of early detection.
• Syphilis: In its secondary stage, syphilis can cause a variety of oral manifestations, including mucous patches or snail track ulcers on the tongue, which could be mistaken for other conditions.

Rare Diagnoses

• Melanotic Macule: A benign pigmented lesion that can appear on the tongue, including the back, and is more common in darker-skinned individuals.
• Kaposi's Sarcoma: A type of cancer that can affect the oral cavity, including the tongue, especially in immunocompromised patients, such as those with HIV/AIDS.
• Median Rhomboid Glossitis: A rare condition characterized by a smooth, red, flat, or slightly raised area on the central back part of the tongue, often associated with a history of oral candidiasis.