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Abstract

Bullous pemphigoid (BP) is a rare autoimmune blistering disorder, infrequently seen in children and exceptionally rare in infants. Due to significant clinical overlap with infectious, genetic, and other autoimmune conditions, definitive diagnosis in infants necessitates histopathologic and immunopathologic evaluation. A three-month-old female presented with a five-day history of erythematous plaques on the hands and feet, which progressed to tense bullae involving the forearms and trunk. The infant remained afebrile and systemically well. The clinical differential included bullous pemphigoid, atypical coxsackievirus infection, epidermolysis bullosa, herpes simplex virus, varicella zoster virus, and bullous impetigo. Bacterial cultures and viral PCR testing were negative. Histopathologic examination of a lesional punch biopsy revealed spongiotic dermatitis with eosinophilic exocytosis overlying papillary dermal edema and a perivascular lymphohistiocytic infiltrate with conspicuous eosinophils. Direct immunofluorescence of perilesional skin demonstrated linear IgG and C3 deposition along the basement membrane zone, confirming the diagnosis of bullous pemphigoid. No family history of autoimmune or blistering disorders was reported, and maternal history was unremarkable. The presence of linear IgG deposition in this age group supports early autoimmune activation against hemidesmosomal components, reinforcing the pathophysiologic basis of disease even in the absence of known triggers. This case expands the clinicopathologic spectrum of early-onset BP and highlights the diagnostic triad essential for recognition in pediatric patients: subepidermal blistering, eosinophil-rich infiltrate, and linear IgG/C3 deposition. Presenting this case provides an opportunity to reinforce diagnostic precision, inform pathology-based algorithms for vesiculobullous disease in infants, and contribute meaningfully to the limited literature on neonatal autoimmune blistering disorders.