Cutaneous porphyrias part I: epidemiology, pathogenesis, presentation, diagnosis, and histopathology

Acute Intermittent Porphyria in a Burn Patient: Case Study and Review of the Literature

Healthcare providers evaluating patients presenting with neurological, visceral, or cutaneous symptoms that are disproportionate to the expected severity may need to consider porphyria in the differential. Porphyria is an inherited condition in which toxic metabolites of the heme pathway are increased. Carriers of porphyrias are asymptomatic and will not present with classical symptoms, nor will levels be elevated, until the disease is induced by certain drugs, hormones, or idiopathic causes such as the stress of trauma. Acute intermittent porphyria (AIP), a form of acute porphyria, is a rare autosomal dominant disease that results in a dysfunctional porphobilinogen deaminase. This consequently increases neurotoxic porphobilinogen and subsequent increase in δ-aminolevulinic acid. Both of these metabolites cause neurovisceral symptoms that afflict the patient in acute attacks. We present a rare case of AIP manifested in a burn patient suffering a burn injury. The patient presented with symptoms indicative of AIP, including altered mental status and abdominal pain accompanied with a chronic history of alcoholism and smoking. A negative work-up, including imaging and findings of associated manifestations consistent with AIP led to a discovery of elevated porphyrins. The patient's course and death due to his injuries gives insight into the presentation of AIP in a burn patient.

Update on the Porphyrias

The porphyrias are a group of rare diseases, each resulting from a defect in a different enzymatic step of the heme biosynthetic pathway. They can be broadly divided into two categories, hepatic and erythropoietic porphyrias, depending on the primary site of accumulation of heme intermediates. These disorders are multisystemic with variable symptoms that can be encountered by physicians in any specialty. Here, we review the porphyrias and describe their clinical presentation, diagnosis, and management. We discuss novel therapies that are approved or in development. Early diagnosis is key for the appropriate management and prevention of long-term complications in these rare disorders.

Histopathology of autoimmune bullous dermatoses: What's new?

Autoimmune bullous dermatoses are characterized by the presence of tissue-bound and often circulating pathogenic autoantibodies targeting structural components of the skin and/or mucous membranes. The diagnostic workup for this heterogeneous group of disorders consists of a multi-step process, of which the light microscopic examination is a crucial component. This review is organized following a classification scheme that is based on two main histopathologic features, namely level of intraepithelial split and composition of the inflammatory infiltrate. Overall, we aim to place emphasis on the histopathologic clues that can assist pathologists in differential diagnosis and review the updates in the literature.

Acitretin mitigates uroporphyrin-induced bone defects in congenital erythropoietic porphyria models

Congenital erythropoietic porphyria (CEP) is a rare genetic disorder leading to accumulation of uro/coproporphyrin-I in tissues due to inhibition of uroporphyrinogen-III synthase. Clinical manifestations of CEP include bone fragility, severe photosensitivity and photomutilation. Currently there is no specific treatment for CEP, except bone marrow transplantation, and there is an unmet need for treating this orphan disease. Fluorescent porphyrins cause protein aggregation, which led us to hypothesize that uroporphyrin-I accumulation leads to protein aggregation and CEP-related bone phenotype. We developed a zebrafish model that phenocopies features of CEP. As in human patients, uroporphyrin-I accumulated in the bones of zebrafish, leading to impaired bone development. Furthermore, in an osteoblast-like cell line, uroporphyrin-I decreased mineralization, aggregated bone matrix proteins, activated endoplasmic reticulum stress and disrupted autophagy. Using high-throughput drug screening, we identified acitretin, a second-generation retinoid, and showed that it reduced uroporphyrin-I accumulation and its deleterious effects on bones. Our findings provide a new CEP experimental model and a potential repurposed therapeutic.

Oral lesions containing amyloid-like material

During oral pathology daily practice, true amyloid may be identified in oral amyloidosis and several odontogenic tumors. However, histologic examination often reveals other oral and perioral diseases with similar eosinophilic, acellular, amorphous substances. These include extensive areas of collagenous sclerosis, fibrin deposition, elastic fiber degeneration, and dentinoid material, which may resemble amyloid under light microscopic examination. These materials are often termed "amyloid-like" due to their close histologic resemblance to true amyloid. The rarity of most of these conditions and their strong histologic similarity may hamper an accurate diagnosis. Definitive diagnosis of these lesions may require clinical correlation; laboratory evaluation; histochemical or immunohistochemical reactions; and, in some cases, genetic investigation. In this review, we describe the main clinicopathologic features of this group of diseases that may manifest in the oral and/or perioral regions and that have in common the presence of amyloid-like material deposition.

Variegate Porphyria Triggered by Acute Hepatitis A Infection

Background

Variegate porphyria (VP) is a rare disorder of haem biosynthesis. We report a novel association with hepatitis A infection.

Patient and methods

A 31-year-old man was diagnosed with acute hepatitis A infection. During recovery, he presented with abdominal pain and a photoaggravated blistering skin eruption.

Results

Urine porphyrin precursors were markedly raised with high coproporphyrin III isomer levels. Faecal protoporphyrin levels were markedly increased and a maximum plasma fluorescence emission at 629 nm was noted.

Discussion

Acute hepatitis A infection, and the associated metabolic stress exerted on the haem biosynthetic pathway, induced overt presentation of latent VP.

LEARNING POINTS

Whole-Exome Sequencing in Idiopathic Short Stature: Rare Mutations Affecting Growth

Idiopathic short stature (ISS) is a common diagnosis of exclusion in patients with short stature (SS). In this article, we aimed to identify the genetic causes of SS in patients with ISS and investigate treatment options. Fourteen children with diagnosis of ISS were identified, and whole-exome sequencing (WES) was subsequently conducted on blood-derived DNA. Five patients were correctly diagnosed with ISS and four had rare mutations that have not been previously reported. Four patients had mutations known to cause SS and one had a mutation that was known not to affect height. WES can help identify rare mutations implicated in ISS.

Sporadic Porphyria Cutanea Tarda as the Initial Manifestation of Hereditary Hemochromatosis

Porphyria cutanea tarda (PCT) is a skin disorder characterized by abnormal heme synthesis. We present a 45-year-old man with intermittent skin lesions recurring annually for years. Skin biopsy and measurement of serum heme precursors confirmed a diagnosis of PCT. He had persistently elevated alanine and aspartate transferase. He was referred to hematology and had genetic testing with iron studies which also revealed hereditary hemochromatosis (HH). Therapeutic phlebotomy was initiated, which led to resolution of iron overload and skin lesions. We highlight the associated conditions of PCT and HH, their common therapy of phlebotomy, and initial manifestations of HH.

Porphyrias: A clinically based approach

BACKGROUND

Porphyrias are a group of metabolic diseases, individually rare but with an important combined prevalence. Because of their pathological complexity and clinical heterogeneity, they present a challenging diagnosis. The present review aims to provide a clinically based approach to the recognition and treatment of these disorders.

METHODS

We carried out a search in PubMed, with the keyword "porphyria", for reviews published in English from 2010 until 2017.

RESULTS

The research yielded 196 papers, of which 64 were included in the final narrative review.

CONCLUSIONS

Porphyrias can be divided based on clinical presentation in acute neurovisceral, chronic cutaneous bullous, chronic cutaneous non-bullous and acute neurovisceral/chronic cutaneous bullous. Each individual porphyria presents a characteristic pattern of porphyrins in plasma, urine, stool and red blood cells. As such, diagnosis is easily obtained by following a simple diagnostic algorithm. Early recognition is key in managing these diseases. Neurovisceral porphyrias require acute support therapy and chronic eviction of precipitating factors. Cutaneous prophyrias, as photosensitivity disorders, rely on sunlight avoidance and, in some cases, specific therapeutic interventions. Given the rarity of these conditions, physician awareness is crucial.

Experience in management of porphyria cutanea tarda in a tertiary referral Brazilian hospital from 2002 to 2017

BACKGROUND

Porphyria cutanea tarda (PCT) is the most common porphyria worldwide. The known acquired precipitating factors that induce PCT include alcoholism, hepatitis C virus infection, human immunodeficiency virus infection, and estrogen intake. Hereditary hemochromatosis is considered an inherited risk factor. The aim of this study was to describe and analyze precipitating factors and family history, with emphasis on PCT management.

METHODS

A retrospective study of 87 patients with PCT was conducted between January 2002 and December 2017.

RESULTS

A male predominance of 1.8 : 1 was found. The median age at diagnosis was 49 years (range 18-71). Family history of PCT was observed in 19.5% of patients. Two or more acquired precipitating factors were present in 42.5%. Patients were treated with antimalarial monotherapy (72.4%), antimalarial combined with phlebotomy (22.9%), and only with phlebotomy (4.6%). Acquired precipitating factors and inherited factors were not associated with treatment group. There was a difference in 24 h-UP normalization rate between treatment groups; combined therapy takes longer than antimalarial monotherapy, 38 months versus 15 months, respectively (CI 95%, 6.5-63.5 vs. 12.9-17) (log-rank test, P = 0.004).

CONCLUSION

Precipitating factors did not seem to be associated with treatment choice; however, all acquired and inherited precipitating factors should be investigated, and the choice between phlebotomy and/or antimalarials should be individualized. All dermatologists treating PCT patients should observe transferrin saturation and ferritin levels to search for underlying hereditary hemochromatosis.

[The cutaneous porphyrias]

The porphyrias are a group of metabolic disorders resulting from an innate abnormality in haem biosynthesis, and the clinical settings of which vary according to the genetic enzyme abnormality in question. These are genetic disorders with autosomal dominant or recessive inheritance of varying penetrance, and whose clinical expression differs according to the preferential location of haem precursors. Different classifications have been proposed according to genetic inheritance, the enzyme anomaly at issue, and clinical expression. The clinical classification distinguishes between acute porphyria (acute intermittent porphyria, porphyria variegata, hereditary coproporphyria), bullous cutaneous porphyrias (porphyria cutanea tarda, porphyria variegata and hereditary coproporphyria), painful photosensitive acute cutaneous porphyrias (erythropoietic protoporphyria and X-linked dominant protoporphyria), and rare recessive porphyrias (congenital erythropoietic porphyria, Doss porphyria, hepatoerythropoietic porphyria and harderoporphyria). Treatment depends on the clinical expression of the disorder.

Porphyrias and photosensitivity: pathophysiology for the clinician

Porphyrias are disorders caused by defects in the biosynthetic pathway of heme. Their manifestations can be divided into three distinct syndromes, each attributable to the accumulation of three distinct classes of molecules. The acute neurovisceral syndrome is caused by the accumulation of the neurotoxic porphyrin precursors, delta aminolevulinic acid, and porphobilinogen; the syndrome of immediate painful photosensitivity is caused by the lipid-soluble protoporphyrin IX and, the syndrome of delayed blistering photosensitivity, caused by the water-soluble porphyrins, uroporphyrin, and coproporphyrin. Porphyrias can manifest with one, or with a combination, of these syndromes, depending on whether one or more types of molecules are being accumulated. Iron plays a significant role in some of these conditions, as evidenced by improvements in both clinical manifestations and laboratory parameters, following iron depletion in porphyria cutanea tarda, or iron administration in some cases of X-linked erythropoietic protoporphyria. While the pathophysiology of a specific type of porphyrias, the protoporphyrias, appears to favor the administration of zinc, results so far have been conflicting, necessitating further studies in order to assess its potential benefit. The pathways involved in each disease, as well as insights into their pathobiological processes are presented, with an emphasis on the development of photosensitivity reactions.

Unraveling the Role of Heme in Neurodegeneration

Heme (iron-protoporphyrin IX) is an essential co-factor involved in several biological processes, including neuronal survival and differentiation. Nevertheless, an excess of free-heme promotes oxidative stress and lipid peroxidation, thus leading to cell death. The toxic properties of heme in the brain have been extensively studied during intracerebral or subarachnoid hemorrhages. Recently, a growing number of neurodegenerative disorders have been associated to alterations of heme metabolism. Hence, the etiology of such diseases remains undefined. The aim of this review is to highlight the neuropathological role of heme and to discuss the major heme-regulated pathways that might be crucial for the survival of neuronal cells. The understanding of the molecular mechanisms linking heme to neurodegeneration will be important for therapeutic purposes.

Recent Developments in the Diagnosis and Management of Photosensitive Disorders

Photodermatoses occur in males and females of all races and ages. Onset can be variable in timing and influenced by genetic and environmental factors. Photodermatoses are broadly classified as immunologically mediated, chemical- and drug-induced, photoaggravated, and genetic (defective DNA repair or chromosomal instability) diseases. Advances in the field have led to improved recognition and treatment of many photodermatoses. The purpose of this focused review is to provide an update on the diagnosis and management of a variety of photodermatoses, both common and less common, with review of recent updates in the literature pertaining to their diagnosis and management.

Genetic ancestry of patients with porphyria cutanea tarda in a country with mixed races: a cross-sectional study (Rio de Janeiro - Brazil)

Porphyria cutanea tarda has a complex etiology with genetic factors not completely elucidated. The miscegenation of the Brazilian population has important implications in the predisposition to diseases. There are no studies concerning the genetic ancestry of patients with porphyria cutanea tarda from a mixed population. Thirty patients living in Rio de Janeiro with sporadic porphyria cutanea tarda were studied for the genetic ancestry through informative markers - INDELS. There was a significant predominance of European ancestry across the sample of patients with porphyria cutanea tarda (70.2%), and a small contribution of African and Amerindian ancestry, 20.1% and 10.9%, respectively.

Photosensitization in Porphyrias and Photodynamic Therapy Involves TRPA1 and TRPV1

Photosensitization, an exaggerated sensitivity to harmless light, occurs genetically in rare diseases, such as porphyrias, and in photodynamic therapy where short-term toxicity is intended. A common feature is the experience of pain from bright light. In human subjects, skin exposure to 405 nm light induced moderate pain, which was intensified by pretreatment with aminolevulinic acid. In heterologous expression systems and cultured sensory neurons, exposure to blue light activated TRPA1 and, to a lesser extent, TRPV1 channels in the absence of additional photosensitization. Pretreatment with aminolevulinic acid or with protoporphyrin IX dramatically increased the light sensitivity of both TRPA1 and TRPV1 via generation of reactive oxygen species. Artificial lipid bilayers equipped with purified human TRPA1 showed substantial single-channel activity only in the presence of protoporphyrin IX and blue light. Photosensitivity and photosensitization could be demonstrated in freshly isolated mouse tissues and led to TRP channel-dependent release of proinflammatory neuropeptides upon illumination. With antagonists in clinical development, these findings may help to alleviate pain during photodynamic therapy and also allow for disease modification in porphyria patients.

SIGNIFICANCE STATEMENT

Cutaneous porphyria patients suffer from burning pain upon exposure to sunlight and other patients undergoing photodynamic therapy experience similar pain, which can limit the therapeutic efforts. This study elucidates the underlying molecular transduction mechanism and identifies potential targets of therapy. Ultraviolet and blue light generates singlet oxygen, which oxidizes and activates the ion channels TRPA1 and TRPV1. The disease and the therapeutic options could be reproduced in models ranging from isolated ion channels to human subjects, applying protoporphyrin IX or its precursor aminolevulinic acid. There is an unmet medical need, and our results suggest a therapeutic use of the pertinent antagonists in clinical development.

Porphyria cutanea tarda: an intriguing genetic disease and marker

Porphyrias are a group of intriguing genetic diseases of the heme pathway, of which porphyria cutanea tarda (PCT) is the most common. Resulting from a defect in enzymes in the porphyria pathway, PCT has been linked to several conditions. Recent studies have demonstrated a change in thinking regarding the human immunodeficiency virus (HIV) and development of PCT. The exacerbation of PCT with contraction of HIV is now believed to result from coinfection from the hepatitis C virus (HCV). Blistering of sun-exposed skin, a classic presenting sign of PCT, is not exclusive to the condition. Cutaneous findings must also trigger physicians to consider additional types of porphyrias, such as variegate porphyria. The diagnosis of pseudoporphyria, which does not result from enzymatic absence, must be considered in patients with photosensitivity and cutaneous bullae. Recent health food trends, such as chlorophyll, have been linked to pseudoporphyria. PCT is a serious condition in which accurate diagnosis is necessary for appropriate management.

Fragility of epidermis in newborns, children and adolescents

Within their first days of life, newborns' skin undergoes various adaptation processes needed to accommodate the transition from the wet uterine environment to the dry atmosphere. The skin of newborns and infants is considered as a physiological fragile skin, a skin with lower resistance to aggressions. Fragile skin is divided into four categories up to its origin: physiological fragile skin (age, location), pathological fragile skin (acute and chronic), circumstantial fragile skin (due to environmental extrinsic factors or intrinsic factors such as stress) and iatrogenic fragile skin. Extensive research of the past 10 years have proven evidence that at birth albeit showing a nearly perfect appearance, newborn skin is structurally and functionally immature compared to adult skin undergoing a physiological maturation process after birth at least throughout the first year of life. This article is an overview of all known data about fragility of epidermis in 'fragile populations': newborns, children and adolescents. It includes the recent pathological, pathophysiological and clinical data about fragility of epidermis in various dermatological diseases, such as atopic dermatitis, acne, rosacea, contact dermatitis, irritative dermatitis and focus on UV protection.

Bullous, pseudobullous, & pustular dermatoses

Several dermatoses are typified by the formation of spaces (blisters; bullae) within or beneath the epidermis. These may be acellular or filled with particular species of inflammatory cells. Etiological categories include infectious, immune-mediated, genetic, drug-related, and idiopathic lesions. Examples of such disorders include impetigo, Herpes virus infections, pemphigus, bullous pemphigoid and pemphigoid gestationis, epidermolysis bullosa acquisita, IgA-related dermatoses, inherited epidermolysis bullosa variants, Hailey-Hailey disease, and porphyria cutanea tarda. Other conditions manifest microscopic acantholysis within the surface epithelium but are not associated with clinical bullae, such as Darier disease and Grover disease. Finally, both infectious and non-infectious causes exist for the development of neutrophilic pustules in the epidermis, as seen in pustular psoriasis, Sneddon-Wilkinson disease (subcorneal pustular dermatosis), and acute generalized exanthematous pustulosis. This review considers the clinical and histological features of all of these diseases.

[Congenital erythropoietic porphyria : An update]

BACKGROUND

Congenital erythropoetic porphria is a very rare type of autosomal recessive nonacute porphyria. Homozygous or compound heterozygous mutations in the uroporphyrinogen III consynthase gene cause a marked enzymatic deficiency of uroporphyrinogen III consynthase, the fourth enzyme along the heme biosynthetic pathway.

CLINICAL PRESENTATION

Clinically, affected patients are characterized by a moderate to severe photosensitivity. Starting early in infancy, they develop blisters, erosions, and exulcerations in sun-exposed areas of the body, often resulting in scar formation and mutilation. Besides the cutaneous changes, hemolytic anemia, transfusion-dependent pancytopenia, hepatosplenomegaly and liver cirrhosis can occur. Due to increased susceptibility for infections and because of the hematological and hepatic complications, affected individuals have a decreased life expectancy, rarely exceeding 40 years of age.

TREATMENT

Currently, no causal treatment is available for the disorder. Therefore, the most important therapeutic modality is strict avoidance of sunlight, preferably by inversion of the day-night rhythm, or at least consequent photoprotection with adequate clothing. In severe cases, bone marrow or stem cell transplantation should be considered.

Protoporphyrin IX: the Good, the Bad, and the Ugly

Protoporphyrin IX (PPIX) is ubiquitously present in all living cells in small amounts as a precursor of heme. PPIX has some biologic functions of its own, and PPIX-based strategies have been used for cancer diagnosis and treatment (the good). PPIX serves as the substrate for ferrochelatase, the final enzyme in heme biosynthesis, and its homeostasis is tightly regulated during heme synthesis. Accumulation of PPIX in human porphyrias can cause skin photosensitivity, biliary stones, hepatobiliary damage, and even liver failure (the bad and the ugly). In this work, we review the mechanisms that are associated with the broad aspects of PPIX. Because PPIX is a hydrophobic molecule, its disposition is by hepatic rather than renal excretion. Large amounts of PPIX are toxic to the liver and can cause cholestatic liver injury. Application of PPIX in cancer diagnosis and treatment is based on its photodynamic effects.

Porphyria Cutanea Tarda Masquerading as Epidermolysis Bullosa Acquisita: A Report of Two Cases

Porphyria cutanea tarda (PCT) is the most common type of porphyria worldwide and is often initially diagnosed when cutaneous manifestations arise. We present two patients where misdiagnosis of PCT occurred due to the condition masquerading as epidermolysis bullosa acquisita histologically. In patients with undifferentiated bullous/erosive skin conditions occurring in photo-distributed regions, PCT should be considered in the differential diagnosis irrespective of histopathological findings on biopsies and further investigated and treated appropriately.