10.11.2014
In erythropoietic porphyria, a very rare disease that typically develops during infancy or childhood, recurrent vesiculobullous eruptions in sun-exposed areas of the skin gradually result in mutilating ulcerations and scarring.
In erythropoietic protoporphyria, the usual reaction to light is erythema and edema followed by thickening and superficial scarring of the skin.
In porphyria variegata, different members of the same family may have either cutaneous manifestations identical to those of porphyria cutanea tarda or systemic involvement analogous to acute intermittent porphyria, or both, or the condition may remain latent {95, 101}. Three forms of porphyria cutanea tarda can be distinguished: sporadic, familial, and hepatoerythropoietic . In the familial form, a dominantly inherited disorder, in addition to the hepatic activity, the extrahepatic activity of uroporphyrinogen decarboxylase is decreased to about 50% of normal.
Clinically, the sporadic form of porphyria cutanea tarda, by far the most common type of porphyria, shows blisters that arise through a combination of sun exposure and minor trauma, mainly on the dorsa of the hands but sometimes also on the face {Fig. In hereditary coproporphyria, a very rare disorder, there are episodic attacks of abdominal pain and a variety of neurologic and psychiatric disturbances analogous to those observed in acute intermittent porphyria and porphyria variegata .
In mild cases, homogeneous, pale, eosinophilic deposits are limited to the immediate vicinity of the blood vessels in the papillary dermis . In severely involved areas, which are most common in erythropoietic protoporphyria, the perivascular mantles of homogeneous material are wide enough in the papillary dermis to coalesce with those of adjoining capillaries. In areas of sclerosis, which occur especially in porphyria cutanea tarda, the collagen bundles are thickened. The bullae, which are most common in porphyria cutanea tarda and least common in erythropoietic protoporphyria, arise subepidermally . The epidermis forming the roof of the blister often contains eosinophilic bodies that are elongate and sometimes segmented (123). On electron microscopic examination, concentric duplications of the basement membrane around the dermal blood vessels are observed. Proof that the perivascular material in porphyria represents excessively synthesized basement membrane material and as such contains type IV collagen is provided by positive immunofluorescence staining with anti-type IV collagen monospecific antibody . In the majority of patients, direct immunofluorescence testing has revealed the presence of immunoglobulins, particularly immunoglobulin G (lgG) , and occasionally also of complement (128), in the walls of blood vessels and at the dermal-epidermal junction of light-exposed skin.
In patients with chronic renal failure who are receiving maintenance hemodialysis, an eruption indistinguishable from that of porphyria cutanea tarda may develop on the dorsa of the hands and fingers during the summer months .
Pseudoporphyria cutanea tarda may also occur following the ingestion of certain drugs, such as furosemide, nalidixic acid, tetracycline hydrochloride, and naproxen (135). You must have JavaScript enabled in your browser to utilize the functionality of this website. The light sensitivity in the six types with cutaneous lesions is caused by wavelengths that are absorbed by the porphyrin molecule. In rare instances, vesicles are present that may resemble those seen in hydroa vacciniforme {93,94,95}. The presence of protoporphyrin in the feces distinguishes porphyria variegata from porphyria cutanea tarda . In the sporadic form, only the hepatic activity of uroporphyrinogen decarboxylase is decreased.


The damaging agent most commonly is ethanol, but iron supplements, estrogen treatment, and hepatitis are also implicated {1 06, 1 07}.
In some cases, there are also cutaneous manifestations indistinguishable from those of porphyria cutanea tarda and porphyria variegata . These deposits are best visualized with a PAS stain, being PAS positive and diastase resistant. In addition, deeper blood vessels may show homogeneous material around them, and similar homogeneous material may be found occasionally around eccrine glands . In contrast to scleroderma, PAS-positive, diastase-resistant material is often present in the dermis in perivascular locations .
Some blisters are dermolytic and arise beneath the PAS-positive basement membrane zone ; others form in the lamina lucida and are situated above the PAS-positive basement membrane zone . This phenomenon, referred to as festooning, is explained by the rigidity of the upper dermis induced by the presence of eosinophilic material within and around the capillary walls in the papillae and the papillary dermis.
Peripheral to this multilayered basement membrane, one observes a thick mantle of unlayered material with the same filamentous and amorphous composition as that of the basement membrane. The presence of small collagen fibrils analogous to reticulum fibrils suggests the presence also of type III collagen. It is unlikely that these deposits indicate an immunologic phenomenon; rather, they are the result of "trapping" of immunoglobulins and complement in the filamentous material. Enzyme determinations may be carried out on cultured skin fibroblasts, erythrocytes, or liver tissue. In erythropoietic protoporphyria, however, liver function tests are usually normal, even though microscopic deposits of protoporphyrin in the liver are found frequently . Because many patients on hemodialysis for renal failure also are receiving furosemide, withdrawal of the drug can determine whether the dialysis or the medication is the cause of the pseudoporphyria, because in drug-induced cases, withdrawal of the drug is curative . In patients with pseudoporphyria, the histologic picture is indistinguishable from that seen in mild cases of porphyria. These wavelengths lie in the 400-nm range, representing long-wave ultraviolet light (UVA) and visible light . It is an autosomal dominant disorder that results from a mutation in the gene that codes for ferrochelatase, which is the final enzyme in the heme synthesis chain .
Also, a sharp fluorescence emission peak at 626 nm is specific for the plasma of porphyria variegata {1 03,104}. Almost all patients are adults, and no clinical evidence of porphyria cutanea tarda is found in other members of the patient's family. The familial form may occur at any age, including childhood, and often, but not always, there is a family history of overt porphyria cutanea tarda. Homogeneous, eosinophilic material is regularly observed, and bullae are present in some instances. It has been suggested thatthe blisters in porphyria cutanea tarda in mild cases arise within the junctional zone but that in severe cases they form beneath the PAS-positive basement membrane zone and thus heal with scarring . Yet, in rare instances, death occurs from liver failure developing swiftly after the initial detection of hepatic dysfunction .


In a series of 180 patients receiving hemodialysis, 28 (16%) showed this type of eruption . The superficial blood vessels show thickened walls, and the PAS-positive basement membrane zone is often thickened as well.
The protoporphyrin is formed in reticulocytes in the bone marrow and is then carried in circulating erythrocytes and in the plasma. A reliable laboratory method for the diagnosis of the porphyrias is now provided by molecular genetics . In some instances, it also contains acid mucopolysaccharides, shown with Alcian blue or the colloidal iron stain , or lipids, demonstrable with Sudan IV or Sudan black B . Scattered through the thick, unlayered zone are solitary collagen fibrils with an average diameter of only 35 nm, in contrast to the 100 nm of mature collagen . Patients with liver failure have very high levels of protoporphyrin in the erythrocytes and at the time of death show extensive deposits of protoporphyrin in a cirrhotic liver.
Normal porphyrin levels in urine, stool, and plasma are the rule in hemodialyzed patients developing clinical signs of porphyria cutanea tarda. When a smear of blood from a patient is examined under a fluorescence microscope, large numbers of red-fluorescing erythrocytes are observed. In cases with severe involvement, intermingled filamentous and amorphous material is seen throughout the upper dermis and even in the mid dermis. However, in a few patients receiving hemodialysis for chronic renal failure, a true porphyria cutanea tarda coexists .
The protoporphyrin is cleared from the plasma by the liver and excreted into the bile and feces {97}.
This pigment exhibits birefringence on polariscopic examination and in unstained sections viewed with ultraviolet light shows red autofluorescence . In such patients, if a certain degree of diuresis persists, urinalysis may not be representative of the porphyria metabolism, and the plasma and fecal porphyrins should always be measured .
In rare instances, hepatocellular carcinoma or a carcinoma metastatic to the liver induces porphyria cutanea tarda {109}. In patients with normal liver function tests, biopsy of the liver mayor may not show portal and periportal fibrosis . In rare instances, fatal liver disease develops quite suddenly, usually in persons of middle age {9B} but occasionally in patients only in the second decade of life . In the familial form of porphyria cutanea tarda, the clinical picture is similar to that of the sporadic form, but the changes are more pronounced. On clinical grounds, the symptoms of most patients resemble those of erythropoietic porphyria, but when symptoms are milder, they resemble those of erythropoietic protoporphyria .
Vesicular eruptions lead to ulceration, severe scarring, partial alopecia, and sclerosis {111}.



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