Female with tense bullae over erythematous base. Diagnosis is?

Ans is 'b' i.e. Bullous Pemphigoid * Tense bullae on erythematous base are classical presentation of bullous pemphigoid.Clinical features of BP* Age group involved is 60-80 years.* There are tense bullae (in contrast to P. vulgaris where bullae are faccid).* Bullae are on erythematous base (in contrast to P.vulgaris where bullae occur on normal skin).* Bullae are distributed on lower part of body (lower abdomen, inner thigh, groins, interiginousarea). Distribution is bilaterally symmetrical (in contrast to P.vulgaris where assymmetric distribution is there). Moderate itching is there (in contrast to P.vulgaris where no or minimal itching occurs).* Nikolsky's Sign is negative (positive in P.vulgaris)