Linear IgA bullous dermatosis in a diabetic patient with chronic renal failure

A 60‐year‐old woman was admitted in October 2000 for disseminated polymorphic papular and vesiculobullous skin lesions with a herpetiform pattern ( Fig. 1). The eruption occurred 1 month prior to admission and was accompanied by intense itching and burning. A few vesicles in the oral mucosa appeared 6 months after the onset of the skin lesions. The patient's history was notable for noninsulin‐dependent diabetes mellitus since the age of 32 years, complicated by arterial hypertension, neuropathy, and nephropathy with subsequent renal failure. The patient started hemodialysis 20 years after the onset of diabetes and was hemodialyzed three times a week for 4 h (index of dialysis adequacy (Kt/v) ≈ 1.3). She had received insulin since the age of 55 years. Furosemide, started in 1998, was withdrawn in October 2000, a few days after admission. Figure 1 Papules, blisters, and erosions with a partial herpetiform pattern (popliteal region) Histopathologic examination of the skin lesions revealed subepidermal blisters with an infiltrate of polymorphonuclear cells within the tips of dermal papillae ( Fig. 2). A diagnosis of linear immunoglobulin A (IgA) bullous dermatosis was confirmed by direct immunofluorescence assay of perilesional skin showing linear IgA (++) and IgG (+) deposits within the basement membrane zone ( Fig. 3). No antiepidermal basement membrane zone or antiendomysial IgA antibodies were detected in the patient's serum. Abnormal laboratory values were as follows: hemoglobin concentration, 10.6 g/dL; red blood cell count, 3.1 × 10 6 /µL; platelets, 99.0 × 10 3 /µL; glucose concentration, 228.0 mg/dL; creatinine concentration, 5.3 mg/dL; glycosuria and proteinuria. 2Histopathology of lesional skin (upper leg): subepidermal blister and infiltrate of polymorphonuclear cells within the dermal papillae (hematoxylin and eosin, × 400)3Immunopathology of perilesional skin (buttock): linear immunoglobulin A (IgA) deposits within the basement membrane zone. Fluorescein‐labeled anti‐IgA antibodies (magnification, × 600) The administration of dapsone at a daily dose of 100 mg resulted in a rapid improvement of the skin lesions. The dose had to be decreased after 3 weeks, however, because of a worsening of the patient's blood morphology and an increase in the proportion of methemoglobin (MetHb) up to 3%. Erythropoietin at a weekly dose of 6000 U was administered. Treatment with tetracycline (1.5 g/day), followed by prednisone (40 mg/day, gradually tapered) and sulfasalazine (4.5 g/day), did not influence the clinical picture of the skin lesions. Finally, dapsone (50 mg/day), together with prednisone (35 mg every second day), was started. With this treatment regimen, almost complete clearing of the skin lesions was achieved and maintained for 1 year. A few small blisters develop periodically and the concentration of MetHb remains within the normal range.