Pseudoporphyria has a similar presentation to PCT but with no abnormalities in porphyrin metabolism. Risk factors include UV radiation exposure; use of medications such as nonsteroidal anti-inflammatory drugs, diuretics, and retinoids; chronic renal failure; and hemodialysis.7
Acute intermittent porphyria is an autosomal dominant disorder due to deficiency of porphobilinogen deaminase, a heme biosynthetic enzyme. Clinical manifestations usually arise in adulthood and include neurovisceral attacks (eg, abdominal pain, vomiting, muscle weakness). Diagnosis during an acute attack can be made by measuring urinary 5-aminolaevulinc acid and porphobilinogen.1
Hereditary hemochromatosis is an autosomal recessive disorder most commonly due to mutations in the HFE gene. Patients typically have iron overload and abnormal liver function test results. The main cutaneous finding is skin hyperpigmentation. Patients also may develop diabetes mellitus, arthropathy, cardiac disease, and hypopituitarism, although most are diagnosed with asymptomatic disease following routine laboratory studies.8
Confirm the diagnosis with total porphyrin measurement
The preferred initial test to confirm the diagnosis of PCT is measurement of plasma or urine total porphyrins, which will be elevated.1 Further testing is then performed to discern PCT from the other, less common cutaneous porphyrias.1 If needed, biopsy can be done to exclude other diagnoses. Testing for HIV and viral hepatitis infection may be performed when clinical suspicion is high.1 Testing for UROD and HFE mutations may also be advised.1
Treatment choice is guided by iron levels
For patients with normal iron levels, low-dose hydroxychloroquine 100 mg or chloroquine 125 mg twice per week can be used until restoration of normal plasma or urine porphyrin levels has been achieved for several months.1 For those with iron excess (serum ferritin > 600 ng/dL), repeat phlebotomy is the preferred treatment; a unit of blood (350-500 mL) is typically removed, as tolerated, until iron stores return to normal.1 In severe cases of PCT, these therapies can be used in combination.1 Clinical remission with these methods can be expected within 6 to 9 months.9
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