60 year female with tense bulla in lower extremity and subepidermal bullous lesion on microscopy, diagnosis is-

Ans. is 'a' i.e., Bullous pemphgoid Important differential diagnosis of vesiculo bullous disordersVesicle / Bullae Itching presentNo or minimal Itching o Moderate ItchingPain absentPain presento Intense Itching|||||Papulovesicular lesions on normal or erythmatous baseonExtensors (knee, elbows), scapular region, buttocks, shoulder and sacral areaTense bullae on erythematous baseonLower part of body eg. lower abdomen, inner thigh, groins, intertiginous areao TenseVesicle / bullae surrounding central erythema, erythematous halo (Target lesion)onface, acral partso FlaccidVesicle / bullae onUpper part of body(face, scalp, trunk & necko Painful rash with vesicles along the distribution of a nerve (dermatome)o Rash is unilateralo Suggestive featuresy Age - 20-40 yrsy B/L symmetric distributiony Mucous membrane involvement - rarey Nickolsky's sign (-)vey IgA in dermal papilla along basement membraneo Suggestive featuresy Sub epidermal bullaey Age - 60-80 yrsy Acantholysis absenty B/L symmetric distributiony Mucous membrane not involvedy Nikolsky's sign (-)vey C3 & IgG along basement membrane (DEJ)o Suggestive featuresy Age - children & youngy Oral mucosa in 20%y Starts acutelyy Bilateral symmetricaly Lasts < 2 weeksy H/O precipitating factors (Drug, infection, UV radiation)o Suggestive featuresy Intraepidermal bullaey Age -> 30-60 yrsy Acantholysis (+) vey Assy metric distributiony Involvement of mucous membraney Nikolsky rs sign (+)vey IgG within epidermal intercellular substanceo Suggestive featuresy Age 45-70 yrsy History of pain, fever before the appearance of vesicley Rash appears before vesiclesy H/O chicken pox in childhood|||||Dermatitis herpetiformisBullous pemphigoidErythema multiformePemphigus vulgarisHerpes zosterNote - Acral parts - Palms, soles, dorsuin of hands & feet & distal parts of forearms & legs.