Mucosa is never involved in which of the following

Dermatitis herpetiformis presents with intense episodic pruritus and skin lesions like erythematous papules which rapidly turn into grouped vesicles.In pemphigus vulgaris skin involvement stas in the form of flaccid blisters. Cutaneous lesions are usually preceded by blisters and erosions of oral mucosa.Toxic epidermal necrolysis (TEN) is a potentially life-threatening dermatologic disorder characterized by widespread erythema, necrosis, and bullous detachment of the epidermis and mucous membranes, resulting in exfoliation and possible sepsis and/or death (see the image below). Mucous membrane involvement can result in gastrointestinal hemorrhage, respiratory failure, ocular abnormalities, and genitourinary complications.mucous membrane involvement is commonly seen in epidermolysis bullosa acquisita page no. 280, 284,287 Reference IADVL's concise textbook of dermatology