Pseudoporphyria is a bullous photosensitivity that clinically and histologically mimics porphyria cutanea tarda

Porphyria cutanea tarda

Porphyria cutanea tarda is the most common subtype of porphyria. The disorder results from low levels of the enzyme responsible for the fifth step in heme production. Heme is a vital molecule for all of the body's organs...

. The difference is that no abnormalities in urine or serum porphyrin is noted on laboratories. Pseudoporphyria has been reported in patients with chronic renal failure treated with hemodialysis and in those with excessive exposure to ultraviolet A (UV-A) by tanning beds.

Pathophysiology

The precise pathophysiologic mechanism of pseudoporphyria is not fully understood. Some drugs, especially non steroidal anti-inflammatory drugs, can trigger pseudoporphyria in the presence of ultraviolet light.

The pathophysiology of pseudoporphyria associated with hemodialysis has not been fully explained. Aluminum hydroxide has been implicated in hemodialysis-associated pseudoporphyria. Aluminum hydroxide is found in dialysis solution and has been shown to produce a porphyrialike disorder after long-term administration in rats.

Frequency

Although fewer than 100 cases are documented in English language literature, pseudoporphyria is most likely underreported in the literature because it is only a symptom of some other affliction, e.g. side effect of medicine or symptom of liver problems.
As the symptoms of pseudoporhphyra have other names, those symptoms are mentioned.

The rarity of porphyria in modern times also makes the use of the term pseudoporphyria obscure.

Race

Although pseudoporphyria has no predilection toward any one race, it has been shown that fair-skinned children who are highly prone to sunburn are more likely to develop naproxen-induced pseudoporphyria than those children with skin types III or higher. Wallace et al. demonstrated that even in the absence of a history of blistering, children with light skin and blue or green eyes are at an increased risk of developing shallow scars on the face while taking naproxen

Naproxen

Naproxen sodium is a nonsteroidal anti-inflammatory drug commonly used for the reduction of pain, fever, inflammation and stiffness caused by conditions such as:...

.

History

A careful history is of utmost importance when the diagnosis of pseudoporphyria is being considered. A personal and family history of hepatitis, porphyria, or photosensitivity disorder must be sought.
Although a genetic factor has not been considered in pseudoporphyria, one case of monozygotic twins developing pseudoporphyria after excessive UV-A exposure from long-term tanning bed use has been documented.
The patient should be thoroughly questioned regarding any symptoms of connective tissue disorder, which may be the underlying pathology of the photosensitivity. Recent reports suggest that a connective tissue disorder may be a predisposing factor in patients using nonsteroidal anti-inflammatory drugs (NSAIDs) who develop pseudoporphyria.

Physical findings

Pseudoporphyria is clinically characterized by increased skin fragility; erythema; and the appearance of tense bullae and erosions on sun-exposed skin, which are identical to those seen in patients with PCT. However, a clinical pearl that may prove helpful in differentiating between pseudoporphyria and PCT is that the classic features of hypertrichosis, hyperpigmentation, and sclerodermoid changes found with PCT are unusual with pseudoporphyria.
A second clinical pattern of pseudoporphyria has a similar presentation to erythropoietic protoporphyria (EPP), an autosomal dominant porphyria resulting from a reduced activity of ferrochelatase.

In contrast to PCT, EPP usually begins in childhood with a history of photosensitivity, often described as a burning sensation immediately after sunlight exposure.
Clinically, EPP is characterized by erythema, edema, shallow scars, and waxy induration of the skin, particularly on the face.
Pseudoporphyria that clinically mimics EPP has been described almost exclusively in children taking naproxen for juvenile rheumatoid arthritis. Naproxen-induced pseudoporphyria seems to have a dimorphic presentation with the PCT-like pattern more often seen in the adult population and the EPP-like pattern more commonly seen in children, although some overlap has been documented.

Causes

Pseudoporphyria can be induced by a wide range of medications, excessive UV-A exposure, and hemodialysis

Hemodialysis

In medicine, hemodialysis is a method for removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies .Hemodialysis can be an outpatient or inpatient therapy...

. One frequently reported drug is naproxen

Naproxen

Naproxen sodium is a nonsteroidal anti-inflammatory drug commonly used for the reduction of pain, fever, inflammation and stiffness caused by conditions such as:...

. A frequent source of UV-A exposure is tanning booth

Tanning booth

A tanning booth is a device that emits ultraviolet radiation, usually for the purpose of a cosmetic tan. They are very similar to a tanning bed, but the design is such that it is intended to be used while standing up, rather than lying down....

s.

As recognition of pseudoporphyria increases and the number of new medications expands, the list of etiologic agents associated with pseudoporphyria will most likely continue to grow. Agents associated with pseudoporphyria are as follows :

Propionic acid

Propionic acid

Propanoic acid is a naturally occurring carboxylic acid with chemical formula CH3CH2COOH. It is a clear liquid with a pungent odor...

 derivatives (NSAIDs) - naproxen, diflunisal

Diflunisal

Diflunisal is a non-steroidal anti-inflammatory drug . It was developed by Merck Sharp & Dohme in 1971 after showing promise in a research project studying more potent chemical analogs of aspirin. It was first sold under the brand name Dolobid, marketed by Merck & Co., but generic versions are now...

, ketoprofen

Ketoprofen

Ketoprofen, 2--propionic acid is one of the propionic acid class of non-steroidal anti-inflammatory drug with analgesic and antipyretic effects...

, nabumetone

Nabumetone

Nabumetone is a non-steroidal anti-inflammatory drug , the only 1-naphthaleneacetic acid derivative. Nabumetone has been developed by Beecham...

, oxaprozin

Oxaprozin

Oxaprozin, also known as Oxaprozinum, is a non-steroidal anti-inflammatory drug , used to relieve the inflammation, swelling, stiffness, and joint pain associated with osteoarthritis and rheumatoid arthritis. Chemically, it is a propionic acid derivative. It is available in 600 mg tablets...

, mefenamic acid

Mefenamic acid

Mefenamic acid is a non-steroidal anti-inflammatory drug used to treat pain, including menstrual pain. It is typically prescribed for oral administration. Mefenamic acid is marketed in the USA as Ponstel....

, rofecoxib

Rofecoxib

Rofecoxib is a nonsteroidal anti-inflammatory drug that has now been withdrawn over safety concerns. It was marketed by Merck & Co. to treat osteoarthritis, acute pain conditions, and dysmenorrhoea...

Antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

s - nalidixic acid

Nalidixic acid

Nalidixic acid is the first of the synthetic quinolone antibiotics...

, tetracycline, oxytetracycline

Oxytetracycline

Oxytetracycline was the second of the broad-spectrum tetracycline group of antibiotics to be discovered.Oxytetracycline works by interfering with the ability of bacteria to produce proteins that are essential to them. Without these proteins the bacteria cannot grow, multiply and increase in numbers...

, ampicillin-sulbactam, cefepime

Cefepime

Cefepime is a fourth-generation cephalosporin antibiotic developed in 1994. Cefepime has an extended spectrum of activity against Gram-positive and Gram-negative bacteria, with greater activity against both Gram-negative and Gram-positive organisms than third-generation agents...

, fluoroquinolones (M Poh, personal communication, June 1999)

Antifungal

Antifungal

* Antifungal medication, a medication used to treat fungal infection s such as athlete's foot , ringworm, candidiasis, etc.* Antifungal protein, a protein family* an adjective referring to a fungicide compound...

s - voriconazole

Voriconazole

Voriconazole is a triazole antifungal medication that is generally used to treat serious, invasive fungal infections. These are generally seen in patients who are immunocompromised, and include invasive candidiasis, invasive aspergillosis, and certain emerging fungal infections.-Invasive...

Diuretic

Diuretic

A diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...

s - furosemide

Furosemide

Furosemide or frusemide is a loop diuretic used in the treatment of congestive heart failure and edema. It is most commonly marketed by Sanofi-Aventis under the brand name Lasix...

, chlorthalidone, butamide, triamterene/hydrochlorothiazide

Hydrochlorothiazide

Hydrochlorothiazide, abbreviated HCTZ, HCT, or HZT, is a first-line diuretic drug of the thiazide class that acts by inhibiting the kidneys' ability to retain water. This reduces the volume of the blood, decreasing blood return to the heart and thus cardiac output and, by other mechanisms, is...

Antiarrhythmics - amiodarone

Amiodarone

Amiodarone is an antiarrhythmic agent used for various types of tachyarrhythmias , both ventricular and supraventricular arrhythmias. Discovered in 1961, it was not approved for use in the United States until 1985...

Chemotherapy

Chemotherapy

Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

 - 5-fluorouracil

Immunosuppressant

Immunosuppressant

An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone...

s - cyclosporine

Sulfone

Sulfone

A sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms. The central hexavalent sulfur atom is double bonded to each of two oxygen atoms and has a single bond to each of two carbon atoms, usually in two separate hydrocarbon substituents.-IUPAC name and...

s - dapsone

Dapsone

Dapsone is a medication most commonly used in combination with rifampicin and clofazimine as multidrug therapy for the treatment of Mycobacterium leprae infections . It is also second-line treatment for prophylaxis against Pneumocystis pneumonia caused by Pneumocystis jiroveci Dapsone...

Vitamin

Vitamin

A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...

s - brewers' yeast, pyridoxine

Pyridoxine

Pyridoxine is one of the compounds that can be called vitamin B6, along with pyridoxal and pyridoxamine. It differs from pyridoxamine by the substituent at the '4' position. It is often used as 'pyridoxine hydrochloride'.-Chemistry:...

Vitamin A

Vitamin A

Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...

 derivatives - etretinate

Etretinate

Etretinate is a medication developed by Hoffmann–La Roche that was approved by the FDA in 1986 to treat severe psoriasis...

, isotretinoin

Isotretinoin

Isotretinoin, INN, is a medication used mostly for cystic acne. It was first developed for brain, pancreatic and other cancers. It is used to treat harlequin-type ichthyosis, a usually lethal skin disease, and lamellar ichthyosis. Its effects are systemic and nonselective...

Muscle relaxant

Muscle relaxant

A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics...

s - carisoprodol

Carisoprodol

Carisoprodol is a centrally-acting skeletal muscle relaxant. Carisoprodol is slightly soluble in water and freely soluble in alcohol, chloroform and acetone. The drug's solubility is practically independent of pH. Carisoprodol is manufactured and marketed in the United States by Meda Pharmaceuticals...

/aspirin

Aspirin

Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...

Nonsteroidal antiandrogens - flutamide

Flutamide

Flutamide is an oral nonsteroidal antiandrogen drug primarily used to treat prostate cancer. It competes with testosterone and its powerful metabolite, dihydrotestosterone for binding to androgen receptors in the prostate gland. By doing so, it prevents them from stimulating the prostate cancer...

Other - hemodialysis, excessive UV-A, cola

Cola

Cola is a carbonated beverage that was typically flavored by the kola nut as well as vanilla and other flavorings, however, some colas are now flavored artificially. It became popular worldwide after druggist John Pemberton invented Coca-Cola in 1886...

, oral contraceptive

Oral contraceptive

The combined oral contraceptive pill , often referred to as the birth-control pill or colloquially as "the Pill", is a birth control method that includes a combination of an estrogen and a progestin . When taken by mouth every day, these pills inhibit female fertility...

 pills (levonorgestrel

Levonorgestrel

Levonorgestrel is a second generation synthetic progestogen used as an active ingredient in some hormonal contraceptives.-Chemistry:...

 and ethinyl estradiol), narrowband

Narrowband

In radio, narrowband describes a channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth. It is a common misconception that narrowband refers to a channel which occupies only a "small" amount of space on the radio spectrum.The opposite of...

 UV-B phototherapy (rarely)

Treatment

Sun avoidance, avoidance of tanning booths, and usage of broad spectrum sunscreen

Sunscreen

Sunblock is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet radiation on the skin exposed to sunlight and thus helps protect against sunburn...

that blocks both UVA and UVB.

Identification and avoidance of the offending drug.