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Hematologic and hepatic manifestations of the cutaneous porphyrias
1Department of Internal Medicine, University of California, Davis, Sacramento.
Insights
This review covers five photocutaneous porphyrias, distinguishing childhood forms like congenital erythropoietic porphyria and protoporphyria, and adult forms like porphyria cutanea tarda. It highlights diagnostic methods and therapeutic approaches for these diverse heme precursor disorders.
Area of Science:
- Biochemistry
- Dermatology
- Hepatology
- Genetics
Background:
- Porphyrias are a diverse group of disorders affecting heme synthesis, leading to various hematologic, hepatologic, and neurologic manifestations.
- Photocutaneous porphyrias present with skin lesions and are classified based on age of onset and specific biochemical profiles.
Purpose of the Study:
- To review five photocutaneous forms of human porphyria, detailing their clinical and biochemical characteristics.
- To discuss diagnostic distinctions between childhood and adult-onset porphyrias.
- To outline current and novel therapeutic strategies for managing these conditions.
Main Methods:
- Analysis of heme precursor profiles in red cells, plasma, urine, and feces.
- Biochemical diagnosis using solvent extraction and chromatographic techniques.
- Review of clinical presentations, including skin lesions and organ-specific manifestations.
Main Results:
- Congenital erythropoietic porphyria (CEP) and protoporphyria are key childhood forms, distinguishable by lesion nature and precursor profiles.
- Porphyria cutanea tarda (PCT) is a common adult form associated with liver disease, effectively treated by phlebotomy.
- Rare subtypes like hepatoerythropoietic porphyria and CEP involve enzyme deficiencies, while hereditary hepatic porphyrias (VP, HCP) are linked to drug-induced acute attacks.
Conclusions:
- Accurate diagnosis of photocutaneous porphyrias relies on differentiating clinical features and specific biochemical marker analysis.
- Therapeutic strategies vary significantly, from phlebotomy for PCT to managing liver disease in protoporphyria and preventing acute attacks in hepatic porphyrias.
- Understanding the diverse manifestations and underlying biochemical defects is crucial for effective patient management.
Abstract:
This chapter has dealt with five photocutaneous forms of human porphyria. The forms are a diverse group of disorders with many different hematologic, hepatologic, and neurologic manifestations. In essence, most photocutaneous porphyrias occurring in childhood will relate to congenital erythropoietic porphyria or protoporphyria. The nature of the skin lesions and a study of the heme precursor profile in red cells, plasma, urine, and feces should easily distinguish these two conditions. CEP is a disease wherein photomutilation is a dominant concern and aggressive new approaches of therapy also have been discussed. In protoporphyria, the dermatologic problem is less severe and the dermatologist should be aware that a subset of patients could develop active liver disease that may lead to fatal cirrhosis. Novel approaches of therapy have been briefly alluded to. With regard to postpubertal photocutaneous porphyria, the classic porphyria cutanea tarda syndrome is associated with liver disease, usually alcoholic with siderosis, and the treatment by phlebotomy to reduce hepatic iron is highly effective. The potential danger of liver carcinoma has been discussed. In subsets of porphyria cutanea tarda, this can be an endemic disease relating to environmental factors, ie, ingestion of polyhalogenated hydrocarbons. The biochemical diagnosis can be attained by fairly straight-forward solvent extraction analyses of urine and feces, showing the dominance of uroporphyrin excretion in the urine and coproporphyrin in the feces. Chromatographic techniques in plasma, bile, and feces reveal a PCT-specific porphyrin: isocoproporphyrin. Rare subtypes with hematologic manifestations, ie, hepatoerythropoietic porphyria and CEP, indicate the wide spectra of disorders that might be associated with a spontaneous deficiency of uroporphyrinogen decarboxylase activity. These latter syndromes are, however, rare. Two hereditary hepatic porphyrias, ie, autosomal dominantly inherited VP and HCP, have been briefly discussed. The hepatic lesion is metabolic, not morphologic, and its expression by the liver relates to its adaptive response to induction of microsomal hemoproteins by a variety of exogeneous and endogeneous compounds, eg, drugs and hormones. Photocutaneous lesions of HCP and VP are identical to PCT, the latter having no neurologic sequelae. In the former two, however, exposure of persons to drugs, such as the hydantoins and barbiturates, can lead to potentially fatal acute porphyric attacks.(ABSTRACT TRUNCATED AT 400 WORDS)