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Home :: Porphyria Cutanea Tarda
Porphyria Cutanea Tarda
Porphyria cutanea tarda (PCT), as the name implies, occurs mostly in adults rather than children. Patients do not present with characteristic photosensitivity but with complaints of "fragile skin" vesicles, and bullae, particularly on the dorsa of the hands, especially after minor trauma; the diagnosis is confirmed by the presence of a pinkish-red fluorescence in the urine when examined with a Wood's lamp. PCT is distinct from variegate porphyria (VP) and acute intermittent porphyria (AlP) in that patients with PCT do not have acute life-threatening attacks (abdominal pain, peripheral autonomic neuropathy, and respiratory failure). Furthermore, the drugs that induce PCT (ethanol, estrogens, and chloroquine) are fewer than the drugs that induce VP and AlP. For classification of the porphyrias.
Causes of Porphyria Cutanea Tarda
In some patients there is a reduction in the liver enzyme uroporphyrin decarboxylase, which catalyzes decarboxylation of the four acetate groups to methyl groups. This reduction of enzyme may occur in familial or nonfamilial PCT.
Symptoms of Porphyria Cutanea Tarda
Affected individuals develop fragile skin, sores (erosions), blisters (vesicles and bullae), and tiny cysts (milia) on the sun-exposed areas i.e. the back of the hands and the forearms. They may notice that they sunburn easily. Some people develop mottled brown patches around the eyes and increased facial hair. Occasionally the skin becomes hardened (sclerodermoid) on the neck, face or chest. There may be small areas of permanent baldness (alopecia) or ulcers.
Diagnosis
By clinical features, pink-red fluorescence of urine and elevated urinary porphyrins.
Other important tests may involve checking the iron levels in the blood, looking for previous liver viral infections, and taking a history to detect aggravating drugs.
Treatment
- Avoid ethanol. Stop drugs that could be inducing PCT, such as estrogen, and eliminate exposure to chemicals (chlorinated phenols, tetrachlorodibenzo-p-dioxin). In some patients, complete avoidance of ethanol ingestion will result in a clinical and biochemical remission and in depletion of the high level of iron stores in the liver.
- Phlebotomy is done by removing 500 ml of blood at weekly or biweekly intervals until the hemoglobin is decreased to 10 g. Clinical and biochemical remission occurs within 5 to 12 months after regular phlebotomy. Relapse within a year is uncommon (5 to 10%).
- Chloroquine is used to induce remission of PCT in patients in whom phlebotomy is contraindicated because of anemia. Since chloroquine can exacerbate the disease and, in higher doses, may even induce hepatic failure in these patients, this treatment requires considerable experience. However, long-lasting remissions and, in a portion of patients, clinical and biochemical "cure" can be achieved.
The best approach currently used by one of us (K. W.) is to start with a course of three consecutive phlebotomies every other day followed by 150 mg of chloroquine PO/d. Close clinical and laboratory (transaminases, porphyrin excretion in urine) is required to adjust the chloroquine dose which is eventually tapered to 150 mg twice a week and continued for several months.
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