Question of the Week # 39

•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?


B. Rheumatoid factor

C. Skin biopsy

D. Hepatitis C serology

E. Hepatitis B serology

Copy Rights: USMLEGalaxy

11 Responses

  1. C
    the patient has porphiryria cutanea tarda

  2. c

  3. D, relationship with hepatitis c and porphyria cutanea tarda..

  4. Ans. D

    PCT is due to a defective enzyme (uroporphyrinogen decarboxylase) in liver . ( the enzyme is involved in hem synthesis).

    PCT begins in mid-adult life especially after exposure to substances that increase the production of porphyrins (precursors of haem) in the liver such as alcohol, estrogen e.g. oral contraceptive, hormone replacement or liver disease.

    Clinical features include Sores (erosions) following relatively minor injuries, Fluid filled blisters (vesicles and bullae) and Increased sensitivity to the sun .
    Characteristically, the urine is darker than usual, with a reddish or tea-coloured hue

    If asked on the exam, consider the diagnosis of Hepatitis C infection ( important association).

    DX – Elevated urinary porphyrins, wood’s light on urine gives marked fluorescence

    Avoid alcohol
    Use tanning creams in sun and avoid sun in acute flare.
    Discontinue estrogens
    Therapeutic phlebotomy to reduce iron stores (this improves heme synthesis disturbed by ferroinhibition of UROD. )
    In patients in whom phlebotomy is not convenient or is contraindicated and in those who have relatively mild iron overload –> use oral chloroquine phosphate (or ) hydroxychloroquine sulfate

  5. C

    Porphyria cutanea tarda (PCT) is a type of porphyria in which affected individuals are sensitive to sunlight. Exposed skin shows abnormalities that range from slight fragility of the skin to persistent scarring and disfiguration. Due to fragility of the skin, minor trauma may induce blister formation. Areas of increased and decreased pigment content may be noted on the skin. Blistering of light exposed skin and increased hair growth are also characteristic.

    PCT is caused by a deficiency of the uroporphyrinogen decarboxylase (URO-D) enzyme in the liver. The disorder can be acquired or can be caused by an inherited gene mutation in the UROD gene. The inherited form of PCT is also called familial PCT and follows autosomal dominant inheritance. Many individuals with a UROD gene mutation never experience symptoms of the disease.

    PCT becomes active and causes symptoms when triggered by an environmental factor that affects liver cells (hepatocytes). These environmental factors include alcohol, estrogens, hepatitis C, and human immunodeficiency viruses (HIV). Individuals who have disorders that lead to excess iron in tissues such as hemochromatosis also have an increased risk of developing PCT. It is usually necessary for an environmental trigger to be present to cause symptoms of either the acquired or inherited type of PCT.

    Agent Orange: Porphyria Cutanea Tarda
    VA recognizes Veterans’ porphyria cutanea tarda (PCT) as associated with exposure to Agent Orange and other herbicides during military service when it appears within one year of exposure to a degree of at least 10% disabling by VA’s rating regulations.

  6. I would love to get the real correct answer to this… As the real diagnosis everyone can guess is PCT, I would go with D as the next step due to trelationship of hep… Since that would be serious. And possibly alter the course of treatment. Why waste time on a skin biopsy in this case??


  7. Hep c

  8. Skin biopsy

  9. C

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