Mucous membrane pemphigoid. Note the erythema and ulcerations on the gingiva.

Mucous membrane pemphigoid. Ulcers are present on the left buccal mucosa.

Mucous membrane pemphigoid.Note the ulcers in the right buccal mucosa.

Mucous membrane pemphigoid.Note the gingival ulceration and bleeding.

Mucous membrane pemphigoid.Low-power photomicrograph showing separation of the epithelium and connective tissue, resulting in a subepithelial blister. This is the result of autoantibodies formed against antigens in the basal lamina.

Photomicrograph of mucous membrane pemphigoid showing separation of the epithelium from the connective tissue in the basement membrane region. This results in a subepithelial blister. The separation is the result of autoantibodies directed against antigens in the basal lamina.

Mucous membrane pemphigoid. Note the erythematous gingiva.

Mucous membrane pemphigoid demonstrating gingival erythema.

Mucous membrane pemphigoid demonstrating gingival erythema.

Mucous membrane pemphigoid. Note the ginvial erythema and ulceration.

Mucous membrane pemphigoid. Note the gingival erythema and ulceration.

Mucous membrane pemphigoid. Note the gingival erythema.

Mucous membrane pemphigoid. A blast of air is causing formation of a blister. This is known as a Nikolsky sign. A Nikolsky sign is not always present in patients with mucous membrane pemphigoid. Other diseases, including pemphigus vulgaris, lichen planus, and lupus erythematosus can sometimes demonstrate a Nikolsky sign.

Mucous membrane pemphigoid. Note the ulcers on the left buccal mucosa.

Mucous membrane pemphigoid. Note the large palatal ulcer.

Mucous membrane pemphigoid. Note the large palatal ulcer.

Mucous membrane pemphigoid. Note the extensive ulceration of the soft palate. The ulcers are covered by a light yellow fibrin clot.

Mucous membrane pemphigoid demonstrating an ulcer of the hard palate.

Mucous membrane pemphigoid with extensive ulceration of the edentulous alveolar ridge.

Mucous membrane pemphigoid. A blast of air is causing the formation of a blister. This is called a Nikolsky sign. It is sometimes present in mucous membrane pemphigoid, pemphigus, lichen planus and lupus erythematosus.

Mucous membrane pemphigoid. Note the intense erythema of the attached gingiva.

Mucous membrane pemphigoid. A blast of air is causing the formation of a blister. This is known as a Nikolsky sign. It is sometimes, but not always, present in mucous membrane pemphigoid, pemphigus vulgaris, lichen planus and lupus erythematosus.

Mucous membrane pemphigoid. High-power photomicrograph showing separation of the epithelium and the connective tissue in the basement membrane region.

Mucous membrane pemphigoid.This is a photomicrograph of a direct immunofluoresence preparation. The white irregular line indicates deposition of autoantibodies in the basement membrane region.

Mucous membrane pemphigoid. This is a high-power photomicrograph demonstrating separation of the epithelium and the connective tissue in the basement membrane region.