A person presents with hemorrhagic fluid in a tense blister at dermoepidermal junction. Most probable diagnosis is:

The pemphigoid group includes a series of chronic diseases in which blisters form within the lamina lucida of the basement membrane dermoepidermal junction). The blister roof is thus the entire epidermis so it is stable. Frequently the blisters are hemorrhagic, fluid filled and tense. No accantholysis occurs, so the Tzanck test is negative. Antibodies are directed against various components of the basement membrane zone. Characteristic of pemphigus vulgaris is an intradermal blister occurring immediately above the basal cell layer and associated with acantholytic cells. The blisters rapidly ruptures, leaving non healing, painful erosions. Pemphigus vegetans usually presents clinically as serpiginous ulcers. Microscopically, the epithelium tends to proliferate and become verruciform. Acantholytic cells may not be conspicuous and eosinophil microabscesses are the most typical histological feature. Drug induced pemphigus can present as pemphigus foliaceous, pemphigus erythematosus, or as pemphigus vulgaris. Moist erythematous crusted scaling plaques and superficial friable blisters are seen. Common drugs responsible are thiol compounds, drugs having a sulph-hydryl group, penicillamine.