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A 6 year old boy, born of second degree consanguineous parents, presented with mildly itchy blisters all over his body of 20 days’ duration. The skin lesions were present for 3–4 days and then ruptured spontaneously. Most of these lesions were healing spontaneously, but a ring of blisters was appearing again around the healed lesions. The child had no preceding history of drug intake and had achieved normal milestones and was vaccinated up to date. There was no family history of a similar disorder. The boy was healthy looking on physical examination, with numerous tense vesicles and bullae on a slightly erythematous skin with erosions and crusting found bilaterally, but asymmetrically on the face, especially in the perioral area (fig 1), neck, forearms, thighs (fig 2), groin, and gluteal region (around the anus and perigenital skin). In most of the locations, these vesicles and bullae were arranged in an annular or rosette pattern around a central crust or an erythematous plaque giving the appearance of a “string of pearls” appearance (fig 2).
Routine investigations of haematological and biochemical parameters were within normal limits. Tzanck smear examination from the skin lesions showed neutrophils only; no acantholytic cells were seen. A Gram stained smear of vesicle fluid demonstrated pus cells, but no bacterial organisms were seen. Histopathological examination of a representative biopsy specimen (back) revealed a subepidermal bulla with plenty of neutrophils. The papillary dermis had an accumulation of neutrophils. These findings were consistent with chronic bullous dermatosis of childhood (CBDC). Direct immunofluorescence study of the perilesional skin (back) demonstrated linear deposits of IgA and C3 at the dermoepidermal junction, confirming our clinical diagnosis of CBDC. The child was started on dapsone at a dose of 50 mg per day. Since new lesions were still appearing even after one week of treatment, the dose of dapsone was increased to 50 mg twice a day. He started responding to treatment symptomatically and the lesions completely resolved by 10 days. The child is being followed up.
CBDC is a rare, chronic acquired subepidermal blistering disease of childhood. Among acquired immunobullous diseases in children, the most commonly seen is CBDC and has homogeneous linear deposits of IgA at the epidermal basement membrane. Histopathological examination reveals a subepidermal bulla with collections of neutrophils along the basement membrane, often accumulating at the papillary tips. It predominantly occurs in preschool children (average age of onset is 5 years). The clinical presentation of CBDC is most often characterised by abrupt onset of pruritic or non-pruritic tense vesicles or bullae that can arise on normal or erythematous skin. Most often these lesions occur in clusters giving a “cluster of jewels” or “string of pearls” appearance. These lesions have a predilection for perioral, lower trunk, buttocks, thighs, and perineal surfaces. Oral lesions may occur. The disorder usually remits by age 6–8 years, in most cases by adolescence. The differential diagnosis of CBDC includes bullous impetigo, dermatitis herpetiformis, bullous pemphigoid, and scabies. Paediatricians frequently misdiagnose CBDC as impetigo. In patients with impetigo, Gram stain should demonstrate leucocytes and bacterial organisms.
CBDC is an IgA mediated disorder characterised by IgA antibodies against two different epidermal and dermal associated antigens with molecular weights of 285 kDa and 97/120 kDa. The majority of cases of CBDC respond to either sulfapyridine or dapsone therapy. Dapsone is begun at 1–2 mg/kg per day increasing at weekly intervals until symptoms are adequately controlled. The dosage of dapsone should not exceed 3–4 mg/kg per day. Recommendations for the follow up of patients on dapsone are: (1) complete blood cell count and liver function tests at baseline, (2) a complete blood cell count weekly for the first month, monthly for next five months, and every six months thereafter, and (3) liver function tests every six months. Addition of systemic steroids may be required in some cases where there are mixed immunobullous characteristics.
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