DP15 A rare immunobullous diagnosis in a varicella zoster-naive patient
Authors: Smith Kirsty , Phillips Christopher , Khan Sabrina , McEntyre Nicholas , Lloyd-Lavery Antonia 
Published: June 2024

Abstract
We present a rare diagnosis in a 41-year-old man referred urgently from the infectious diseases team with a 3-week history of extensive itchy and painful mucocutaneous blistering and ulceration. This initially affected his hands, spreading to involve his limbs and trunk. His oral and genital mucosae were similarly affected. He reported lethargy and weight loss secondary to reduced oral intake but was otherwise systemically well. He had hypertension managed with amlodipine but he had not recently taken any other medications or supplements. He had emigrated to the UK from Ghana 6 months earlier and no contacts were similarly affected. Examination revealed multiple tense vesicles and bullae with crusted erosions scattered across his trunk and limbs on a background of urticated erythema involving approximately 40% of his body surface area. Haemorrhagic bullae were present on his tongue, his labial and buccal mucosa, and his genital mucosa. He had an extensive infection screen. Of note, viral polymerase chain reaction of vesicular fluid was negative and he was noted to have negative varicella zoster virus (VZV) IgG, in keeping with his history of never previously having chickenpox. Histopathology demonstrated subepidermal blistering with neutrophils and a neutrophil-rich superficial perivascular inflammatory infiltrate and small collections of neutrophils in dermal papillae with incipient clefting. Direct immunofluorescence showed linear deposition of IgG and C3 along the basement membrane zone localizing to the base on salt-split skin. Enzyme-linked immunosorbent assay to collagen VII was strongly positive, and it was negative to BP180/230. On the basis of his clinical findings and investigation results, epidermolysis bullosa acquisita (EBA) was diagnosed. After careful consideration and discussion with the patient, the decision was made to delay systemic immunosuppressive treatment until he had completed VZV vaccination. He was initially managed with clobetasol ointment, Trimovate cream (clobetasone butyrate, nystatin and oxytetracycline calcium) and fluticasone mouthwash. He subsequently commenced prednisolone 40 mg daily, with complete resolution of blistering within 1 month, leaving areas of postinflammatory hypopigmentation, scarring and milia. The introduction of dapsone 50 mg daily has enabled him to gradually wean the dose of prednisolone without further flares. EBA is a very rare immunobullous disease characterized by autoantibodies directed against collagen VII. Different clinical phenotypes are recognized, including a mechanobullous phenotype characterized by acral involvement, skin fragility, scarring and milia; an inflammatory phenotype with skin changes resembling pemphigoid; and a mucosal dominant phenotype. His case was complicated by the need to delay systemic immunosuppression to enable VZV vaccination, an important consideration when long-term immunosuppression may be required. Fortunately, our patient has shown an excellent response to dapsone, highlighting the value of this medication in EBA, among other immunobullous diseases.