What Is Porphyria Cutanea Tarda?

Porphyria cutanea tarda (PCT) is both an inherited disease and an acquired disease. It was first named by Wald Ensnstrom in 1937. Clinically, it is characterized by photosensitive dermatitis, facial hairiness, skin scarring, roughening, thickening, and pigmentation changes. Porphyria disease without neuropathy, some patients have liver damage.

Turkish porphyria

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Porphyria cutanea tarda (PCT) is both an inherited disease and an acquired disease. It was first named by Wald Ensnstrom in 1937. Clinically, it is characterized by photosensitive dermatitis, facial hairiness, skin scarring, roughening, thickening, and pigmentation changes. Porphyria disease without neuropathy, some patients have liver damage.

Turkish porphyria

porphyria cutaneous tarda

Delayed skin porphyria; symptomatic porphyria

Dermatology> Nutrition and metabolic disorders

Hematology> Red blood cell disease> Porphyria

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Turkish porphyria is reported all over the world, and the sporadic type is also known as nonfamily, accounting for 80% of all cases. It usually develops in middle age (average 45 years), and about 10% of patients develop scleroderma-like skin lesions. % To 20% of patients with this disease are complicated by diabetes; some are associated with cirrhosis, jaundice and methemia. The Chinese Journal of Dermatology reported in 1990 that the disease accounted for 23.9% of the total number of porphyrias in the same period. Men are more common than women.

The etiology is unknown, and it is generally believed that it develops under the combined effect of various acquired factors on the basis of hereditary background.

genetic factors

Urinary porphyrinogen decarboxylase deficiency. Its gene is located on chromosome 1q34. Urinary porphyrinogen decarboxylase deficiency in liver tissues is found in all patients with Turkish porphyria, but genetic factors are only found in familial and few sporadic patients. It is autosomal dominant.

Excessive iron load

Liver iron deposits can be seen in more than 80% of patients with Turkish porphyria. Iron deposits are moderate. Blood deposits are used to reduce iron deposits, or trials of iron expulsion therapy can provide patients with clinical and biochemical relief. Stopping bloodletting or using iron can relieve relapse in patients, indicating that iron is closely related to the disease.

Inhibitory enzyme activity factor

There are the following: inhibitory enzyme active factors present in the liver; estrogen; alcohol increases ALA activity and promotes iron absorption. The deficiency of urinary porphyrinogen decarboxylase is limited to the liver, and the enzymes in the red blood cells are normal.

Insecticide hexachloride poisoning causes epidemic of the disease

Benzene hexachloride is a urinary porphyrinogen decarboxylase inhibitor. Other inhaled aromatic hydrocarbon compounds and rust removers can cause human porphyria.

May be combined with porphyria

Patients with multiple liver benign and malignant tumors can be associated with porphyria without cirrhosis. The fluorescence response of some patients is only found in the tumor site, and the mechanism is unknown.

Hepatitis C

Hepatitis C has recently been found to be closely related to sporadic porphyria. In some areas, 80% of patients with sporadic disease have chronic hepatitis C, and the mechanism by which hepatitis C virus inhibits porphyrinogen decarboxylase activity is unclear and needs further study.

Renal Failure

Chronic renal failure patients with hemodialysis may be complicated by sporadic porphyria.

Studies have shown that splicing point mutations in some patients result in the loss of six exons of mRNA, resulting in a decrease in enzyme activity. It has also been reported that some patients have mutations in the coding region of the gene. Urinary porphyrinogen decarboxylase is an enzyme that catalyzes the continuous decarboxylation reaction of uroporphyrinogen to fecal porphyrinogen. This enzyme deficiency causes urinary porphyrinogen to accumulate in the liver and increase excretion from the urine. The enzyme activity of red blood cells in familial patients is only half that of normal people, but many family members with genetic defects have neither clinical accumulation of urinary porphyrinogen in the liver nor increased excretion in urine, indicating that there are other conditions for the occurrence of this disease. In many patients with sporadic porphyria, the deficiency of uroporphyrinogen decarboxylase is limited to the liver, and there is no deficiency in red blood cells. In these patients, the urinary porphyrinogen decarboxylase has a lower catalytic activity than normal, but its enzyme is determined by immunochemical Normal, combined with its lack of family history and no evidence of genetic defects, suggest that some artificially acquired enzyme activities are reduced, rather than hereditary diseases.

Further research proves that iron can inhibit the activity of uroporphyrinogen decarboxylase, and at the same time promote the production of uroporphyrinogen by promoting the synthesis of amino-gamma ketovaleric acid (ALA) and porphyllogen, resulting in the accumulation of uroporphyrinogen III.

And the liver has normal immune-reactive enzyme synthesis, but its catalytic biological activity is reduced. Most patients have no family genetic history, suggesting that liver enzymes may be partially inhibited by inhibitors. Increased iron load can stimulate the secretion of inhibitors and cause symptoms in patients. In recent years, with the increase of estrogen application by women, the proportion of women with sporadic cases of this disease has increased, indicating that estrogen may also inhibit uroporphyrinogen decarboxylase, but it does not exclude genetic factors, because the incidence of only a small proportion of patients taking drugs.

Animal tests have shown that the above compounds can inhibit enzyme activity, and iron loading can aggravate the enzyme inhibition of the above compounds. There are three reasons: one is the increase in iron load caused by excessive blood transfusion, the other is that hemodialysis and peritoneal dialysis cannot effectively clear the uroporphyrin that exists in the plasma in a protein-bound form, and the third is that some harmful metabolites of uremia can inhibit urine. Porphyrin decarboxylase activity leads to urinary porphyrinogen accumulation and pathogenesis.

There are two clinical types of porphyria in Turkey. The sporadic type is also known as nonfamilial type, accounting for 80% of all cases. It usually develops in middle age (average 45 years). The liver urinary porphyrinogen decarboxylase activity is abnormal and normal in other tissues. The liver enzyme activity returned to normal after remission. Some cases are related to hepatotoxic substances, known as acquired toxic PCT; the other type is a family type, which is an autosomal genetic disease. Patients and unaffected family members may have abnormalities in the liver and erythrocyte uroporphyrinogen decarboxylase. Its activity and concentration are reduced by about 50%. Patients often develop early in life, and most of the PCTs that occur before the age of 20 belong to this type. Patients have mild to moderate photosensitive dermatitis, which is more common in summer. The affected areas are mostly exposed areas such as the hands, face, neck, upper chest, lower legs, and feet. The rash is mostly erythema, which can also manifest as solar urticaria, with conscious itching or burning. Chronic damage is blisters, bullae, erosions, scabs, and superficial scars. The blisters range in diameter from 2 to 30 mm, are round or irregular, and the blister fluid is more clear but bloody. The fragility of the skin on the hands and wrists increases, and minor trauma can lead to multiple painless red erosions. Scraping with the nail can scrape away the affected skin, which is called Dean's sign. About 10% of patients develop scleroderma-like lesions, which are more common on the neck, chest, and face, but can also occur in non-exposed areas, and it is difficult to distinguish clinically and histopathologically from scleroderma. There are miliform rashes on the scars on the back of the hands, fingers, and face. One third of patients had pigmentation or loss. Peripheral orbits can see purple-red spots similar to dermatomyositis. A few cases caused deformity and disfigurement due to scarring. Others included nail detachment, auricular dystrophic calcification, cataracts, and scleral ulcers. 15% to 20% of patients with this disease are complicated by diabetes; some are associated with cirrhosis, jaundice and methemia.

A few cases caused deformity and disfigurement due to scarring. Others included nail detachment, auricular dystrophic calcification, cataracts, and scleral ulcers. 15% to 20% of patients with this disease are complicated by diabetes; some are associated with liver cirrhosis.

Histopathology: The bullae are located under the epidermis, there are a small number of inflammatory cells in the dermis, elastic fibrosis, and the PAS-positive and amylase-resistant substance deposits at the junction of the dermal papilla blood vessels and the epidermis. A type of eosinophil can be found in the epidermis above the bullae. It is segmentally homogeneous, PAS-positive, and has type IV collagen and laminin components. The linear arrangement is called caterpillar body. The diagnosis is specific. Direct immunofluorescence examination showed linear deposition of IgG and C3 at the junction of the epidermis and blood vessels. Liver iron deposits, histopathological changes of cirrhosis can be seen.

According to the skin delayed photosensitivity, skin damage, red urine, laboratory examination of urine urinary porphyrin excretion increased significantly, which can make a diagnosis. The diagnosis should pay attention to the causes of porphyria, such as drinking, history of taking estrogen, and history of chemical poisoning. Patients over 60 years of age should pay attention to liver tumors.

Attention should be paid to the exclusion of pleomorphic solar rash, vaccinia-like vesicular vesicular disease, niacin deficiency deficiency, scleroderma, drug photodermatitis, various bullous diseases, impetigo, etc. Hemodialysis may cause pseudo-delayed porphyria, which may have a rash similar to this disease, but urine, feces, and blood porphyrin measurements are normal and can be identified.

The onset of Turkish porphyria is insidious and progresses slowly. There is no onset of acute porphyria, and sometimes skin light sensitivity is not obvious, and it is easy to miss diagnosis. Prone to cirrhosis or liver cancer.

Harmful factors should be removed, especially alcohol should be banned. Avoid using drugs that are harmful to the liver, such as barbiturates, estrogen, hydroxy chemicals, iron, etc. Avoid sun and trauma and apply sunscreen.

Sulfobromide sodium, collagen, interferon, barbitur

Urinary porphyrin, estrogen, fecal porphyrin, urobilinogen, serum iron, amylase, erythropoietin, hemoglobin, interferon