S6C37P31-Porphyria

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S6C37P31-1: The margin of a sub-epidermal bulla is represented to the right side of the field. The roof of the bulla shows the features of the epidermis of an acral site; there is compact hyperkeratosis. The papillary dermis is fibrotic. Dermal papillae are preserved; they are elongated along the floor of the bulla; the pattern might be characterized as “festooning.” Vessels of the papillae are dilated; vessels at a slightly deeper level have thickened, hyalinized walls. The lesion is free of inflammatory cells. The basal layer of the roof of the bulla shows focal areas in which basal keratinocytes are either not represented, or they demonstrate degenerative changes with loss of a defined basement membrane. In other areas showing a basal layer, a basement membrane is represented; focally, it appears to be on the epidermal side (porphyria cutanea tarda).

S6C37P31-2: This example of a lesion of porphyria cutanea tarda shows a sub-epidermal bulla with a thin layer of epidermis as the roof. This lesion also shows the epidermal changes associated with an acral site; this is the common site for biopsy in the setting of porphyria cutanea tarda; by recognizing the site and some of the basic features, such as festooning of the dermal papillae and mild inflammatory infiltrates, the observer should be able to suggest the possibility of porphyria as the histologic diagnosis. Islands of squamous epithelium along the floor represent regeneration of epithelium; they provide evidence that the lesion is old and late in its evolution.

S6C37P31-3: At a higher magnification, the dermis is relatively free of inflammatory cells. Dermal papillae project into the subepidermal defect. Focally, the papillary dermis forming the floor of the bulla is pale with poor definition of collagen fibers. In areas, the floor is ragged and fibers project into the defect; in other areas, a membrane provides a sharply defined interface. There is a thin layer of fibrin loosely attached along the floor.

S6C37P31-4: This non-acral site shows solar elastosis. There is a small, cell-poor, subepidermal defect; the neighboring epidermis shows acanthosis and intercellular edema. The papillary dermis is widened and fibrotic; it appears to be hyalinized and is hypocellular. The hyalin extends along vessels into the reticular dermis (adventitial sclerosis in a lesion of variegate porphyria).

S6C37P31-5: At the margin of the bulla, the basal unit of the epidermis shows widening of inter-cellular spaces; there are occasional lymphocytes and histiocytes among the basal keratinocytes. The basement membrane zone is fibrotic.The fibrosing reaction involves the papillary dermis; it extends a short distance into the upper portion of the reticular dermis.The pattern of sclerosis is not that of either the delicate, edematous matrix of lichen sclerosis et atrophicus, or the more densely fibrous matrix of superficial morphea. Some of the whorls in the area of sclerosis are interpreted as obliterated (acellular) vessels.

S6C37P31-6: At a deeper level of the reticular dermis, the spaces among collagen bundles are widened. A vessel shows perivascular edema. The wall of the vessel is thickened and laminated; the lamellae are hyalinized. The vascular changes might be compared to those of erythropoietic protoprotoporphyia; the process is, in part, a perivascular hyalinosis.

 

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