Microbial disease	Malignant neoplasms
• Herpetic stomatitis	Blood disorders
• Chickenpox	• Anaemia
• Herpes zoster	• Leukaemia
• Hand, foot, and mouth disease	• Neutropenia
• Herpangina	• Other white cell dyscrasias
• Infectious mononucleosis	Gastrointestinal disease
• HIV infection	• Coeliac disease
• Acute necrotising gingivitis	• Crohn's disease
• Tuberculosis	• Ulcerative colitis
• Syphilis	Rheumatoid diseases
• Fungal infections	• Lupus erythematosus
Cutaneous disease	• Behcet's syndrome
• Lichen planus	• Sweet's syndrome
• Pemphigus	• Reiter's disease
• Pemphigoid	Drugs
• Erythema multiforme	• Cytotoxic agents
• Dermatitis herpetiformis	• Nicorandil
• Linear IgA disease	• Others
• Epidermolysis bullosa	Radiotherapy
• Chronic ulcerative stomatitis
• Other dermatoses