Approach Considerations
Porphyrias with photocutaneous manifestations should be considered in the differential diagnosis of bullous disease of dialysis. To exclude a true porphyria, a plasma or serum porphyrin assay is recommended. The test result will be grossly abnormal due to true porphyria in an individual with compromised renal function. Fecal porphyrin analyses may also reveal increased porphyrin excretion in such cases. [12]
However, in patients on hemodialysis or peritoneal dialysis, plasma porphyrin levels may be increased because of reduced excretion, in the absence of enzyme deficiency. [13]
The possibility of aluminum toxicity should be excluded.
Laboratory Studies
Plasma or serum porphyrin concentrations typically far exceed normal upper limits in true porphyrias in individuals with end-stage renal disease. Quantitative fecal porphyrin analyses may reveal abnormally high porphyrin excretion in such cases. Aluminum toxicity can be excluded by obtaining a serum aluminum level.
Histology
Light microscopic examination of a biopsy of a blister reveals a cell-poor subepidermal bulla indistinguishable from that of a true porphyria, with edematous dermal papillae and a scant perivascular lymphocytic infiltrate. [1] Festooning of dermal papillae and caterpillar bodies in the epidermis can be observed. Staining with periodic acid-Schiff and collagen IV stains could show thickening of vessel walls. [14]
Ultrastructural studies show thickening of the dermal venular walls and dermoepidermal junction due to replicated basal laminae, hypogranulated mast cells, and granulofilamentous hyaline masses in the dermal connective tissue that appear to be secreted by adjacent fibroblasts. [15]
Direct immunofluorescence examinations have revealed the presence of IgG and, inconsistently, IgA, IgM, fibrin, and complement around the dermal venules, with IgG and complement sporadically noted at the dermoepidermal junction or bulla floor. [1, 8, 16]
Deposition of IgG at the dermoepidermal junction has been found in pseudoporphyria, mostly homogenous, not intense, and finely delineated. [14]
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Hands of a transfusion-dependent patient on long-term hemodialysis. Several uremia-related cutaneous disorders are visible. The pigmentary alteration results from retained urochromes and hemosiderin deposition. The large bullae are consistent with either porphyria cutanea tarda or the bullous disease of dialysis. All nails show the distal brown-red and proximal white coloring of half-and-half nails.
