PMC6848154_01
(A) Initial clinical presentation of the patient's buttocks showing severe hidradenitis suppurativa lesions complicated with multifocal squamous cell carcinoma. (B) Inflammatory swelling of the patient's buttocks and surrounding squamous cell carcinoma localization, 1 week after pembrolizumab administration. (C-H) Widespread mucocutaneous blistering disease 3 weeks after pembrolizumab with tense blisters (indicated by arrows) (C), erythema and edema of the face, pseudomembranous conjunctivitis and eyelid erosions (D), pustular lesions (E), large erythematous plaques (F), erosive stomatitis (G), and erosions of the glans penis (H).
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F1
Clinical examination revealed a diffuse involvement of the buttocks, perineal, and perianal regions, with multiple interconnecting tracts and abscesses across entire areas (Figure 1A). One week after the first pembrolizumab administration (2 mg per kg), an intense inflammatory swelling affecting the HS areas was noted, followed by a relapse of the bullous cutaneous eruption (Figures 1B,C). Three weeks after the infusion, the patient developed erythema and edema of the face, bilateral pseudomembranous conjunctivitis with mucus discharge, and eyelid erosions (Figure 1D). Concomitantly, widespread polymorphic cutaneous lesions including flaccid and tense blisters, erosions, erythematous plaques, and pustular lesions occurred (Figures 1E,F). Mucosal examination revealed a severe stomatitis, crusting and bleeding erosions on the lips that extended beyond the vermilion border (Figure 1G), as well as erosions of the glans penis (Figure 1H).
Histological examination by hematoxylin and eosin staining of skin biopsies. (A) Suprabasal acantholysis and intraepidermal blister formation (original magnification x100). (B) Intraepidermal pustule containing neutrophils and eosinophils, as well as epidermal spongiosis with exocytosis of eosinophils (original magnification x100).
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F2
Histological examination by hematoxylin and eosin staining showed a suprabasal acantholysis and intraepidermal blister formations, without keratinocyte necrosis (Figure 2A), supporting the hypothesis of a pemphigus and ruling out drug-induced toxic epidermal necrolysis. A second biopsy demonstrated a spongiotic dermatitis with exocytosis of eosinophils, intraepidermal pustule formation (Figure 2B), and superficial perivascular dermal infiltrate of eosinophils and lymphocytes.