Oral Candidiasis (Thrush): This is a common condition, especially in immunocompromised individuals, characterized by white patches on the tongue and other parts of the mouth. It's often associated with antibiotic use, steroid inhalers, or poor oral hygiene.

Aphthous Ulcers: These are small, painful ulcers that can appear on the tongue and are very common. They can be triggered by stress, minor mouth injury, or certain foods.
Lichen Planus: An inflammatory condition that can affect the mucous membranes inside the mouth, including the tongue, leading to white, lacy patches or red, inflamed tissues.
Geographic Tongue: A benign condition characterized by areas of depapillation on the tongue surface, giving it a map-like appearance. It can be associated with psoriasis or other conditions but often occurs without any underlying disease.

Oral Cancer: Although less common, any unusual or persistent lesion on the tongue should raise suspicion for oral cancer, especially in smokers or those with a history of tobacco use.
Erythema Multiforme: A skin condition that can also affect the mucous membranes, including the tongue, and is characterized by target-like lesions. It can be a reaction to medications or infections.
Pemphigus Vulgaris: A rare autoimmune disease that can cause blistering of the skin and mucous membranes, including the tongue. It's critical to diagnose early due to its potential severity.

Behçet's Disease: A form of vasculitis that can cause a variety of symptoms, including oral ulcers that might appear on the tongue. It's more common in certain parts of the world, like the Middle East and Asia.
Sjögren's Syndrome: An autoimmune disorder that primarily affects the glands that produce tears and saliva, but can also cause oral lesions and tongue discomfort.
Kawasaki Disease: Although primarily known for affecting children and causing fever, rash, and lymphadenopathy, it can also cause oral mucosal changes, including on the tongue.