•A 46-year-old fisherman and Vietnam veteran presented with a recurrent rash on his arms and legs and a painful, swollen area on his left leg of several days’ duration. The rash had been a problem for about two years and was treated with several courses of antibiotics for cellulitis. The patient reported that for the past two years his skin had been prone to blister and tear with minor trauma and that at times his urine appeared to be dark reddish in color. On examination, he had a slight fever and an area of cellulitis on his left leg. His face was erythematous. On his hands, arms, and legs were vesicles and small bullae, some crusted lesions, and hypopigmented and hyperpigmented macules. What is the most important next step in diagnosis?
A. ANA
B. Rheumatoid factor
C. Skin biopsy
D. Hepatitis C serology
E. Hepatitis B serology
Filed under: USMLE Test Prep |
Archer USMLE Step 3 Blog 
May be D because of common association of Porphyria Cutanea tarda with hepatitis C.
I would also choose D, seem more like PCT.
D