Linear IgA bullous dermatoses in an Indian child with IgG predominance: a unique case report from a tertiary care hospital of Eastern India.

Linear IgA disease is a subepidermal autoimmune blistering disorder with linear IgA deposit along the basement membrane zone. Clinically it presents as tense blister surrounding erythematous plaques, the so-called 'crown of jewels'1 appearance. Many authors believe that linear IgA disease and bullous pemphigoid are two ends of same clinical spectrum.1 Mixed immunobullous disorder was the name given to IgA, IgG, C3 positivity. However, a linear pattern of IgA deposit in the basement membrane zone on direct immunoflorescence is the gold standard for diagnosis. The first line treatment consists of corticosteroid and dapsone. We report a unique case of 4-year-old Indian boy, having second degree consanguinous parents, who presented to our outpatient dermatology department with multiple moderately pruritic erythematous plaque and tense blisters over the previous 10-12 days. Most of the blisters appeared with the classical 'string of pearls' appearance over the perioral region, gluteal region, inner side of the thigh, palms, soles, penis, feet, hands and hard palate (Fig 1). The blister was ruptured by the boy himself during itching. It was his first episode. No family history of similar disease or drug history was present and the boy was vaccinated up to date according to the national immunisation schedule of India. A skin biopsy with 4 mm punch had been done and simultaneously he was started on 15 mg prednisolone (weight 11 kg) and 25 mg dapsone after doing G6PD report. His routine blood test showed eosinophillia and lymphocytosis. Other blood reports were within normal limits. HPE reports showed subepidermal bullaand many micro-abscesses in the dermal papillae containing neutrophils and eosinophils. DIF showed linear deposition of both IgG and IgA with IgG predominance and no C3 deposition. We diagnosed linear IgA dermatoses based upon its clinical features and HPE features despite IgG predominance. The patient responded drastically to dapsone and prednisolone. Within 11 days of starting medications the existing lesions healed with hypopigmentation and no new blisters appeared. Linear IgA disease or chronic bullous disorder is a rare bullous disorder of childhood characterised by linear IgA deposition at dermoepidermal junction. The major target antigen is the ectodomain of BP180. It has bifocal age predilection: in children it occurs between 6 months and 10 years and in adult after 60 years. Diagnosis is mainly based on HPE and immunological reports. We report this case for its uniqueness and to emphasise the fact that although the condition is termed linear IgA dermatoses it can present with IgG predominance; the disease course and response to treatment are the same as in IgA predominance, as shown here and as previously shown by Powell et al. [ABSTRACT FROM AUTHOR]