P097 Atypical pemphigoid and an acneiform eruption in a patient with inflammatory bowel disease

Abstract We report the case of a 20-year-old man with a 4-year history of an atypical immunobullous disorder. He initially presented with a 4-week history of a mildly pruritic, pustular eruption on his scalp, face and trunk. Examination revealed tense serpiginous pustular tracts on the scalp, and moderate facial and truncal papulopustular acne. Histopathology showed epidermal acanthosis, and intense superficial inflammation of hair follicles with granulation tissue, polymorphs and eosinophils. The differential diagnosis included fungal and bacterial infections, and his scalp responded to terbinafine and ciprofloxacin, with partial improvement of his face and trunk. Ten months later, he developed a new tense bullous eruption on the face, trunk and oral mucosa. Biopsy showed intraepithelial blisters with eosinophils and linear IgG deposition at the dermoepidermal junction. He responded rapidly to high-dose oral prednisolone, which was tapered over 3 months. On tapering, his acne worsened, and further biopsy showed folliculitis with linear IgG, IgM and C3 deposition at the dermoepidermal junction. Dapsone was initiated, and after 2 years without flare-ups, treatment was tapered. However, a pustulovesicular eruption rapidly developed on his scalp and back. Concurrently, he was diagnosed with ulcerative colitis, controlled with mesalazine. Given the atypical presentation and discordant histopathology and direct immunofluorescence findings, an expert immunobullous opinion was sought. His working diagnosis is two concurrent conditions: an atypical pemphigoid and a separate acneiform/pustular eruption possibly on the pyoderma gangrenosum–hidradenitis suppurativa spectrum in the context of irritable bowel disease. He is now well controlled on dapsone and doxycycline, with isotretinoin added recently, given an overarching clinical feature of an acneiform eruption at present.