PA17 A challenging case of refractory childhood pemphigus vulgaris

Abstract An 11-year-old boy presented with a 2-month history of oral ulceration and blisters. He was previously well. On examination he had haemorrhagic ulceration of the lips, buccal mucosa and tongue, and multiple superficial erosions affecting the scalp, face, trunk, limbs and penile shaft. He was admitted with suspected Stevens–Johnson syndrome. However, skin biopsy revealed intraepidermal suprabasal acantholytic blistering with tombstoning and accompanying eosinophils. Direct immunofluorescence showed intra­epidermal ‘chicken wire’ pattern of IgG and C3 deposition, diagnostic of pemphigus vulgaris (PV). Anti-desmoglein (Dsg)1 and anti-Dsg3 antibody titres were elevated at 142 and 132 U mL−1, respectively. He commenced oral prednisolone 20 mg daily, but continued to develop new blisters with 11-kg weight loss due to limited oral intake. He was transferred to a tertiary centre. Prednisolone was increased to 30 mg (1 mg kg−1 per day) and azathioprine (2 mg kg−1 per day) was started. Multidisciplinary team management included oral medicine, dietetics and psychology. Chest X-ray and abdominal ultrasound showed no evidence of underlying malignancy. Despite initial improvement, his disease flared shortly after discharge. Azathioprine was increased, leading to healing of cutaneous blisters, but oral ulceration persisted. Mycophenolate mofetil (MMF) (10 mg kg−1 twice daily) was added, leading to disease stabilization enabling prednisolone tapering. He had already developed cushingoid features and unfortunately flared on reducing prednisolone. On increasing MMF to 20 mg kg−1 twice daily, disease remission was eventually achieved, and azathioprine and prednisolone were stopped. One month later his disease flared, requiring further oral prednisolone. Following discussion with a specialist centre, he was assessed for treatment with rituximab. However, while awaiting an infusion bed, his condition improved and prednisolone was slowly weaned. Repeat anti-Dsg1 and anti-Dsg3 antibody titres are awaited and rituximab is currently withheld. PV is an immunobullous condition characterized by IgG autoantibodies targeting Dsg1 and Dsg3. It is rare in children, accounting for only 1.4–3.7% of all cases of PV. Diagnostic delay is common due to its rarity in this age group. Treatment is challenging due to the absence of evidence-based guidelines specific to childhood PV. Furthermore, children are more susceptible to the adverse effects of systemic corticosteroids, such as iatrogenic Cushing syndrome, growth retardation and adrenal suppression. A systematic review of the use of rituximab in childhood and juvenile PV analysed 18 studies comprising 46 patients (Shrivastava P, Mariam S, Abid L et al. Rituximab in childhood and juvenile pemphigus vulgaris: a systematic review. Cureus 2024; 16: e58288). Almost all cases achieved complete or partial remission after rituximab, mostly without relapse and only minor side-effects. A wide range of dosing regimens were used. Our case highlights the challenges in managing refractory PV in this age group.