Bullous pemphigoid in infancy

Bullous pemphigoid (BP) is an autoimmune, subepidermal blistering disease typically affecting the elderly and remains rare in children and infants. Paediatric BP often presents with mucosal involvement, and in infants, commonly affects the hands and feet. The pathogenesis is thought to be similar to that of adult BP with autoantibodies to BP180 (type VII collagen) having been described in the literature. Here, we present a case of BP occurring in a 2-month-old, investigating the potential role of vertical transmission of autoantibodies.

A 2-month-old female infant presented with blistering eruptions initially localised to the hands and feet, which rapidly extended to the groin, neck, arms, and chest. The antenatal and birth history were unremarkable, and there was no family history of autoimmune diseases. The infant was systemically well. Physical examination revealed tense and flaccid bullae on the hands and feet, deep-seated vesicles on an erythematous base on the torso, and some erosions (Figure 1). Mucosal surfaces were unaffected. Viral and bacterial swabs were negative. Histopathology of skin biopsies showed eosinophilic spongiosis and subepidermal bulla formation, with indirect immunofluorescence demonstrating linear C3 and IgG deposition at the dermal-epidermal junction. Serum indirect immunofluorescence was positive for BP180 antibodies, confirming the diagnosis of BP. The infant was treated with high-potency topical corticosteroids (0.05% betamethasone dipropionate) and a short course of oral antibiotics. Significant improvement and complete resolution of the lesions were observed by 6 months of age, with no relapse. The mother had no history of BP or pemphigoid gestationis and no peripartum skin lesions. However, serum indirect immunofluorescence testing of the mother revealed the presence of BP230 antibodies. Six months later, repeat testing showed the absence of antibodies in both mother and child.

The exact cause of BP remains unclear, although certain triggers have been identified such as drug-induced BP and infections.¹ A potential trigger in neonates and infants may include the transplacental transfer of antibodies, a known mechanism that forms the foundation for maternal immunisation strategies where antibodies may be present up to 6–12 months from birth.^{2, 3} Transfer of pathogenic antibodies has been seen to cause transient disease in infants from asymptomatic mothers such as in neonatal lupus and thyroid disease. In neonatal BP, BP180 antibodies are recognised as the pathogenic cause of the neonatal onset of disease.^{4, 5}

We postulate that our patient's mother developed low levels of BP180 as well as BP230 antibodies, during pregnancy, with active transplacental transfer of BP180 antibodies, leading to levels capable of inducing clinical disease in her baby. Due to the half-life of IgG antibodies (21 days), by the time of testing, maternal levels of anti-BP180 had fallen below the detectable limit, whilst anti-BP230 was still detectable.

This case underscores the importance of considering BP in the differential diagnosis of infantile blistering eruptions and suggests that transplacental transfer of antibodies can play a role in triggering this condition in infants and neonates, with maternally derived autoantibodies lasting up to 12 months. This may have implications for the mother in future pregnancies.

There was no funding for this article.

The authors declare no conflicts of interest.

Patient consent was obtained from the parents for publication.