A 60 years old man presented with itchy tense blisters on normal looking skin and urticarial rash, investigation done for the diagnosis:

Ans. a. Direct immunofluorescence (Ref: Harrison 19/e p372, 18th/426-428)A 60 years old man presented with itchy tense blisters on normal looking skin and urticarial rash. This patient is suffering from pemphigoid. Investigation done for the diagnosis direct immunofluorescence.The most likely diagnosis in this patient with tens blisters on normal looking skin associated urticarial plaques as seen in the figure are bullous pemphigoid.Immunologically Mediated Blistering DiseaseDiseasePemphigus vulgarisBullous PemphigoidLinear IgA DiseaseDermatitis HerpetiformisAuto antigenDesmoglein 3QBP230 > BP180BPAG 2Epidermal and tissue transglutaminaseHistologyEpidermalAcantholytic blister in suprabasal spinous cell layerSubepidermal blister with eosinophil rich infiltrateQ in perivascular and vesicular sites.Subepidermal blister with neutrophils in dermal papillaeQSubepidermal blister with neutrophils in Dermal papillaeQDirect ImmunofluorescenceMicroscopyCells surface deposits of IgG on keratinocytes in fishnet patternLinear band of IgG and/ or C3 in epidermalBMZLinear band of IgA, inepidermalBMZGranular deposits of IgA in dermal papillaeQAssociationsHLA-DR4 and DRW6QHLA-DQb1 * 0301- HLA-B8 (+)-TNF2 alleleSubclinical gluten sensitive enteropathy (100%)HLA-B8 (60%) / DRW3 (95%)and HLA-DQW2 haplotype (95-100%)Clinical featuresFlaccid blisters, denuded skin, oro- mucosal lesionsQLarge tense blisters on flexor surfaces and trunkQPruritic small papules on extensor surfaces occasionally larger, acneiform blisters in adultsExtremely pruritic small vesicles on elbows, knees, buttocks and posterior neckQPemphigoidLarge, tense blisters on flexor surface located over lower part of bodyQ (limbs >trunk)Non-itchy and painlessQMainly seen in patients over 60 yearsQMucosa is not involvedQPathology:Subepidermal blisters without acantholysisQSubepidermal collection of IgG, C3-complement. eosinophils, polymorphsQDiagnosis:Direct immunofluorescence: Linear band of IgG and/or C3 in epidermal basement membrane zoneQTreatment:Systemic steroids, immunosuppressants