Pretibial dystrophic epidermolysis bullosa with localized cutaneous amyloidosis: Coincidental or secondary amyloidosis?

Here, we describe the case of a patient with pretibial dystrophic epidermolysis bullosa (PDEB) with amyloid deposition. The patient was a 40‐year‐old Japanese woman who presented a blistering eruption in the pretibial area with flat violaceous‐brown lichenoid papules. The histology of the blister revealed a subepidermal bulla with antibodies bound to basement membrane antigens on the blister roof by immunoflourescent mapping. Electron microscopy revealed a blister cleavage plane below the lamina densa. The histology of the lichenoid papules showed amyloid deposition in the papillary dermis. Because it was confined to just beneath the bulla base of the blister specimen, the amyloid deposition may have been derived from degenerated keratinocytes induced by damage to the epidermal–dermal junction due to blister formation in PDEB in this case. PDEB, in general, is often misdiagnosed as lichen amyloidosis; however, some PDEB cases could actually be associated with amyloid deposition.