Mechanism of Blister Formation in Porphyria Cutanea Tarda: I. Histopathological Observation of Blisters in Three Cases of Porphyria Cutanea Tarda

Abstract

We performed a histopathological investigation of the bullous lesions in 3 cases of porphyria cutanea tarda. All cases showed subepidermal bullae by light microscopy. PAS positive materials were present on the roof of the bullae and partially present on their bases. Electronmicroscopically, the basal lamina was clearly recognized on the base. From these results, we suggest that the blister in porphyria cutanea tarda occurs initially within the junctional zone; this initial bulla may quickly change into a dermolytic bulla with additional stimulation.

Estudo da imunofluorescência direta, imunomapeamento e microscopia ótica na porfiria cutânea tardia

“…29 This degenerative phenomenon in the basal cells would explain why some authors claim that bullae can occur above the basal membrane. 3,27,28,30 They conclude that cleavage is a consequence of photodynamic injury of lysosomes, affecting endothelial cells, keratinocytes and dermal cells of the basal layer. 29 In our study, we used antigen immunomapping to determine the level of cleavage of bullae in seven patients.…”

“…30 Some authors believe that the blister initially originates in the junction zone and then, with additional stimulus, it quickly becomes a dermalcleavage blister; this would explain the occurrence of scars. 28 Other authors have hypothesized that patients with PCT have exposed skin so rigid that it does not tolerate friction or trauma. 2 Reinforcing this hypothesis, it was experimentally observed in patients with active PCT that exposed skin with normal clinical appearance presented cleavage formation in electron microscopy.…”

“…This explains why vascular injury is more pronounced than changes at the DEJ in this condition. 16 In PCT, the blisters result from variable cleavage, sometimes in the lamina lucida, 3,27,28 sometimes in the papillary dermis 2,15,29 or at the level of basal keratinocytes that show degenerative changes. 30 In some patients, the three types of cleavage can be observed in different biopsies, or even in the same biopsy.…”