PMC9818675_01
Clinical appearance of the skin lesions. a Scattered violet-brown papules and nodules <2 cm in diameter were observed on the back. a, b Many of the papules and nodules had central umbilicated necrosis or keratin plugs. c Two tense bullae and five erosions were present on the dorsal aspect of the left foot.
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F1
Physical examination revealed scattered violet-brown papules and nodules <2 cm in diameter on the trunk and extremities, many of which had central umbilicated necrosis or keratin plugs (Fig. 1a, b). In addition, two tense bullae and five erosions were noted on the dorsal aspect of the left foot (Fig. 1c).
a-f Histopathological findings of the skin lesions. A biopsy specimen from a nodule revealed a cup-shaped crust above the epidermis (H&E, original magnification, x20; a) and altered collagen fibers toward the external surface (arrows) (H&E, original magnification, x100; b). c The collagen fibers stained blue with Masson's trichrome (original magnification, x100). d A biopsy specimen from a bulla showed a sub-epidermal blister with moderate infiltration of eosinophils and lymphocytes. Direct immunofluorescence showed linear deposition of IgG (e) and C3 (f) along the basal membrane zone.
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F2
Histopathology of a biopsy specimen from a nodule revealed invagination of the epidermis with basophilic debris (Fig. 2a) and altered collagen fibers toward the external surface (Fig. 2b, c). Histopathological examination of a bulla demonstrated a sub-epidermal blister with moderate infiltration of eosinophils and lymphocytes (Fig. 2d). Direct immunofluorescence revealed linear deposition of immunoglobulin G and C3 along the basal membrane zone (Fig. 2e, f).