This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
An autoimmune disease is – a) Pemphigus vulgarisb) Psoriasisc) Lichen planusd) Acne vulgaris 
Select and explain. 
A. abc, B. bc, C. acd, D. bcd
A: abc
Answer: A: abc 
Explanation: Autoimmune skin disorders

Autoimmune bullous skin disorders


Pemphigus
Bullous pemphigoid
Dermatitis herpetiformis

Lichen planus

Lichen planus is believed to be an autoimmune disorder as it often occurs concurrently with other autoimmune disorders like primary biliary cirrhosis, diabetes, chronic active hepatitis.

Psoriasis

 The theory that psoriasis is an autoimmune disorder is based on the fact that scientist have found an abnormally large number of T cells in the patch of psoriasis.

Autoimmune connective tissue disorders

Lupus erythematosus
Dermatomyositis
Scleroderma
Mixed connective tissue disease
Bechet's disease