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Case Reports

Abstract

Bullous pemphigoid (BP) is an immunobullous dermatosis caused by autoantibody formation against bullous pemphigoid antigens 1 and 2. BP is characterized by a pruritic phase preceding tense bullae formation distributed on the flexor limbs, trunk, and intertriginous skin folds. Histopathology of BP classically shows a subepidermal blister with direct immunofluorescence (DIF) displaying linear deposition of IgG and C3 along the dermal-epidermal junction and IgG deposition along the epidermal side, or “roof”, of the blister with indirect immunofluorescence (IIF). A 66-year-old Caucasian male with newly diagnosed acute myeloid leukemia (AML) was evaluated for pruritic bullae and erythematous plaques. The hematoxylin and eosin stain (H&E) biopsy demonstrated perivascular CD117 and myeloperoxidase positive mononuclear cells, consistent with leukemic myeloblast cells. The DIF biopsy revealed linear deposition of IgG and C3 along the dermal-epidermal junction with areas of subepidermal blistering and deposition of IgG antibodies against the blister roof. In the setting of this patient’s immunofluorescence biopsy findings consistent with BP, the leukemic myeloblast cells were thought to be representative of background inflammation rather than leukemia cutis. Leukemia cutis presents with sheets of blast cells in the dermis, as opposed to the perivascular pattern seen here. While BP has been reported to be associated with chronic lymphocytic leukemia (CLL) in the literature, there are few mentions of BP associated with AML, and the finding of perivascular myeloblast cells is unique. This case underscores the association of BP with hematologic malignancies and supports the need for further investigation into the pathophysiology of BP in AML.