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Autumn 2015, Vol. 23 No. 3

Hong Kong J. Dermatol. Venereol. (2015) 23, 147-148


Dermato-venereological Quiz

Dermato-venereological Quiz

MM Chang 張苗, CMT Cheung 張敏彤, PCL Choi 蔡祥龍

Case

A 57-year-old Chinese man presented with 3 days' history of lower limb purpura with blisters. He had underlying poorly controlled diabetes mellitus. The eruption involved the legs, buttocks and dorsum of the hands and was asymptomatic. There was no history of insect bites or use of new medications. On admission, the patient had a low grade fever but was otherwise well. Examination revealed multiple haemorrhagic blisters with surrounding roundish purpura (Figure 1). Urine Multistix® was positive for RBC and protein. His WCC was 12 and CRP 137. Otherwise, his renal and liver function, albumin, C3 and C4 levels were normal. His autoimmune markers, hepatitis serology, throat swab, urine and blood culture were negative. Serum IgA was not raised and serum protein electrophoresis did not show a monoclonal band. Blister fluid was negative for bacterial and viral culture. Renal biopsy showed diabetic glomerulosclerosis with 5% cortical scarring and IgA nephropathy with low chronicity grade.

Figure 1

An incisional skin biopsy was obtained on the leg for histological evaluation (Figures 2 & 3).

Figure 2 Skin biopsy. Haematoxylin & eosin stainm magnification x 100.

Figure 3 Skin biopsy. Haematoxylin & eosin stain, magnification x 400.

Questions

  1. What are the differential diagnoses?
  2. What does the biopsy show?
  3. What is the diagnosis?
  4. What is the treatment?