Introduction:
Porphyria cutanea tarda (PCT) is a condition that is affected by both hereditary and environmental factors like smoking or consuming alcohol. PCT results when there is a shortage of an enzyme that produces heme (a component of hemoglobin that carries oxygen in the blood circulation). This condition also affects the liver. Painful lesions appear on the skin surface exposed to the sun and are the main symptom of PCT.
This condition is easy to find with skin blisters on the affected person’s skin. A few blood tests and urine analyses confirm the disease. The condition is treated by drawing blood from the body through the veins. In addition, administering certain medications like painkillers and Hydroxychloroquine (antimalarial drugs) that reduce the amount of iron in the blood is considered.
What Is Porphyria Cutanea Tarda?
Porphyria is a class of diseases that happens when there is an accumulation of an enzyme that is responsible for porphyrin production. Cutaneous refers to skin and skin-related, and tarda means the time between afternoon and early evening.
What Causes Porphyria Cutanea Tarda?
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Genetic Causes: The mutations in the gene UROD (uroporphyrinogen decarboxylase) cause PCT. The gene UROD is responsible for producing the enzyme uroporphyrinogen decarboxylase, which plays an essential role in heme synthesis. Hemoglobin is a kind of protein present in the RBC (red blood cells - a blood component) that carries oxygen in the blood. Hemoglobin is composed of heme and globin. The heme consists of iron and is responsible for oxygen transit throughout the body.
The human body utilizes certain enzymes like aminolevulinic acid synthetase (ALAS), aminolevulinic acid dehydrogenase (ALAD), and porphobilinogen deaminase (PBDG) to convert some compounds into porphyrins (a substance necessary for hemoglobin functioning). In addition, some enzymes like uroporphyrinogen III synthase (URO3S), uroporphyrinogen III dehydratase (UROD), and coproporphyrinogen oxidase (CPO) convert these porphyrins into heme.
When any disturbance occurs in this process, the porphyrins accumulate in the body without converting to heme leading to skin damage and excess iron build-up in the body. The deficiency of the enzyme UROD leads to PCT.
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Acquired Causes:
What Are the Types of Porphyria Cutanea Tarda?
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Type I: Acquired or sporadic (80 % of the affected cases). This type affects the liver mainly and occurs in the middle-aged population.
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Type II: Hereditary or familial (20 % of the affected cases). This type is genetically inherited from the parents, and the deficiency of the enzyme (UROD) affects all the blood cells. This type is sometimes seen in children.
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Type III: This type is hereditary and rare but does not involve defects in the UROD gene. A defect in an unidentified gene causes type III.
Type I and II are more common.
What Are the Symptoms of Porphyria Cutanea Tarda?
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Blisters on the skin surface are exposed to the sun as the skin of the face, arms, feet, and hands.
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Abnormal hair growth in the face.
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Flimsy and itchy skin.
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Increased sensitivity of the skin to sun exposure (photosensitive).
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Crust formation and scar formation in the skin.
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Red and inflamed skin.
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Wound formation on the skin, even on minor injuries.
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Hyperpigmentation or darkening of the skin
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Dark-color urine.
What Are the Tests to Find Portal Cutanea Tarda?
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Physical Examination: A physical examination is performed by the physician to check for the classical signs of PCT, like blisters on the skin and hyperpigmentation.
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Porphyrin Test: This test measures porphyrin levels in the blood, urine, and stool samples collected from the patient. Porphyrin levels are elevated in the urine and stools in patients with PCT.
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Complete Blood Count: A blood sample from the patient is collected and screened for the levels of red blood cells, white blood cells, platelets, and hemoglobin. These are a few components present in the blood.
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Liver Function Test: Liver function test is a group of blood tests that screens the enzymes and proteins in the liver. Liver enzymes like alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT) are screened. Bilirubin levels are also screened. Proteins like albumin, globulin and fibrinogen are also screened to assess any abnormal function in the liver.
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Genetic Tests: A blood test to detect the changes in the gene UROD.
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Serum Ferritin: This blood test screens for the presence of ferritin (a protein that consists of iron). Elevated serum ferritin levels reveal an excess presence of iron in the body.
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UROD Enzyme Activity Assay: A blood sample is collected from the patient to screen for the UROD enzyme activity in the red blood cells. It is a confirmatory test for PCT if the enzyme levels are decreased.
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HCV (Hepatitis C Virus) Test: A blood test that screens for the presence of antibodies to the hepatitis C virus.
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HIV Test: A blood that screens and detects the human immunodeficiency virus.
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Skin Biopsy: A small portion of the skin is removed and viewed under a light microscope to view the pathological changes.
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Liver Biopsy: In a liver biopsy, a small portion of the liver is removed with forceps to view pathological changes at microscopic levels. This procedure is done to evaluate the presence of iron in the liver. In addition, a biopsy is performed in patients with suspected malignancies.
How Is Porphyria Cutanea Tarda Treated?
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Stopping Estrogen: One of the prime factors that trigger the disease, like consuming medications that contain estrogen and oral contraceptive pills, has to be stopped.
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Phlebotomy: This technique involves the removal of the blood from the body through the veins to remove the excess iron present in the blood. Five to eight episodes of phlebotomies will be considered.
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Medications:
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Chloroquine And Hydroxychloroquine: Medications like Chloroquine and Hydroxychloroquine will be recommended in patients with anemia or when the vein approach is challenging in phlebotomy. These medications are antimalarial drugs and also reduce the iron levels in the blood and are recommended in a dosage of 100 mg twice a week for Hydroxychloroquine, and 125 mg of Chloroquine two times a week.
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Iron Chelators: Iron chelators like Deferiprone are medications that combine with iron and cause it to dissolve in the water. It is excreted out of the body during urination.
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Pain Killers: Pain-killer medications like Acetaminophen will be recommended to reduce the pain caused by skin blisters.
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Antibiotics: Antibiotic medications like Cephalosporins prevent infections caused by specific organisms in the skin lesions.
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Lifestyle Modifications: Lifestyle modifications like stopping alcohol consumption and quitting smoking that trigger the condition will be recommended. Wear long-sleeve clothes, a hat with a wide brim, sunglasses, and sunscreen that can protect against skin damage from sun exposure.
What Is the Incidence of Porphyria Cutanea Tarda?
The condition occurs in people of both genders. The symptoms usually develop in early adulthood.
What Are the Complications of Porphyria Cutanea Tarda?
Liver abnormalities appear in a few patients.
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Hepatic Siderosis: Build-up of iron in the liver.
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Hepatic Steatosis: Accumulation of fat in the liver.
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Portal Triaditis: Swelling in some parts of the liver.
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Periportal Fibrosis: Thickening or scarring of the areas around the portal vein.
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Cirrhosis: Replacement of healthy liver tissues by scar tissues.
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Hepatitis C: Inflammation or swelling of the liver due to hepatitis C virus infection.
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Hepatocellular Carcinoma: Cancer in the liver.
What Is the Prognosis of Patients With Porphyria Cutanea Tarda?
The prognosis is good in patients with porphyria cutanea tarda with average life expectancy. However, comorbid conditions like liver disease and tumors may result in recurrence.
Conclusion:
Porphyria cutanea tarda is a rare genetic condition that causes painful blisters on the sun-exposed surface of the skin. The deficiency of the enzyme UROD in heme synthesis is responsible for the disease. Other environmental factors like consuming alcohol and tobacco smoking also trigger the condition. A few symptoms, like crust and scar formation, hyperpigmentation, hypopigmentation, etc., occur. And they are treated with medications, etc. However, the chances of recurrence are minimal otherwise. Therefore, porphyria cutanea tarda is not a fatal condition, and with appropriate treatment and lifestyle modifications, the lifespan of the patient is improved.
