What is Pemphigus Foliaceus?
Pemphigus is a serious, autoimmune disease that results in blistering of the skin. It happens because your body mistakenly produces antibodies that attack special proteins called desmogleins – these proteins are essential for holding skin cells together. This disease can generally impact both your skin and the lining of your mouth (mucosal lesions). However, there is a specific type of pemphigus, called pemphigus foliaceus (PF), which only affects the skin and not the mouth. PF is an acquired form, brought on by a specific kind of antibody known as immunoglobulin G (IgG). This antibody wrongly targets a particular type of desmoglein (desmoglein-1), found in a layer of the skin called the epidermis.
What Causes Pemphigus Foliaceus?
Pemphigus foliaceus is a skin condition that has been linked to the presence of certain genetic factors known as HLA-DR4, DR-14, and DR-1. However, unlike another skin disease called pemphigus vulgaris, there isn’t one particular genetic variant, or ‘allele’, that has been singled out as a cause for this condition.
Risk Factors and Frequency for Pemphigus Foliaceus
Pemphigus foliaceous is a less common disease globally compared to pemphigus vulgaris. It is seen equally in both men and women, typically appearing between the ages of 50 to 60. However, it is important to know that it can also occur in children.
There’s a type of pemphigus foliaceous that is quite common in Tunisia and Brazil, where it’s often referred to as ‘fogo selvagem’. This form often appears in individuals who share a genetic connection, like family members. Despite this, it’s not a contagious disease and there’s no evidence that it can be spread through blood or other body fluids.
Signs and Symptoms of Pemphigus Foliaceus
Pemphigus Foliaceus (PF) is a medical condition where most patients aren’t severely ill, but still may experience discomfort. Common complaints include feelings of burning, itchiness, and pain. Usually, it starts off subtly with a few scattered and crusted lesions appearing in areas like the scalp, face, chest, and upper back. Blistering is not typically noticeable due to their shallow nature and the ease with which they rupture. What often remains visible are the crust and scales left behind. The Nikolsky sign, a skin condition where light rubbing of the skin results in exfoliation, may be present. In some cases, the disease can remain localized for years, but it may also rapidly spread, leading to a red scaly rash covering the body. Involvement of the mucous membranes (like the inside of the mouth or the lining of the nose) is relatively rare, even in severe cases.
There are different types of PF, including one that initially mirrors dermatitis herpetiformis (an intensely itchy rash), particularly in the early phase. This version of the disease may evolve into classical PF or even precede a more severe form of the disease called pemphigus vulgaris. However, generally, this tends to follow a mild course.
Another form of PF is called Pemphigus Erythematosus, which is characterized by features common to both lupus erythematosus and PF. Symptoms include scaly, red lesions on the nose and cheeks in a butterfly-like pattern. Sunlight can worsen the condition. Involvement of the oral mucosa is fairly uncommon.
Conditions like myasthenia gravis – a long-term neuromuscular disease – and thymoma – a type of tumor – have been found in association with both pemphigus vulgaris and PF diseases.
Testing for Pemphigus Foliaceus
To rule out the possibility of a medication causing a skin condition known as pemphigus foliaceus, your doctor will thoroughly review all the medications you’re currently taking.
To diagnose pemphigus, a sample of your skin from a fresh lesion is taken for a kind of test known as a biopsy. The biopsy helps your doctor see where the skin blisters are forming. Alongside this, another test is carried out to confirm the presence of specific proteins known as autoantibodies in your skin. This test can be conducted in two ways: by examining the skin around the lesion (direct immunofluorescence) or by using a special kind of test called an ELISA.
A key feature of pemphigus is the presence of a specific autoantibody, IgG, against skin cells called keratinocytes. It’s important to note, if this specific test (direct immunofluorescence) is negative, then your doctor might question whether it’s really pemphigus. To get a clear result, the skin sample for this test is often taken from a normal-looking area of skin close to the lesion, as it’s harder to detect these proteins in blistered skin.
These tests can produce results that look identical to another type of pemphigus, known as pemphigus vulgaris. Here, proteins known as intercellular IgG and C3 spread through the skin. Sometimes, these proteins are found only in the top layers of the skin.
Another type of immunofluorescence, known as indirect immunofluorescence, can detect pemphigus foliaceus in more than 85% of cases. The ELISA test can detect a specific type of autoantibody in up to 71% of cases, but another method, immunoblotting, is less accurate.
Recently, trichoscopy, which is a method of examining the scalp, has proven to be useful in diagnosing scalp pemphigus. This tool can identify common features such as bleeding or yellow crusts. A new feature known as the “fried egg sign” (yellow dots with a whitish halo) has been identified as a way to spot this condition.
Treatment Options for Pemphigus Foliaceus
Pemphigus foliaceus, a rare skin disorder, was often deadly before the introduction of steroid treatments, particularly for older patients with other health problems. Now, thanks to steroids and other medications that suppress the immune system, the death rate from this disease has been greatly decreased.
Corticosteroids, a type of medication that reduces inflammation, are the first course of treatment for pemphigus foliaceus. The common ones are Prednisone or Prednisolone.
Other medications like Azathioprine and Mycophenolate Mofetil are often used in combination with steroids, although it’s not always clear when these additional medications should be introduced. It should be noted that it may take a long time – between two and 12 months – for Mycophenolate Mofetil to show results.
If the disease proves resistant to these treatments, or if the patient cannot take immune-suppressing medications, other options include hydroxychloroquine, dapsone, methotrexate, intravenous immunoglobulin, or rituximab.
Because these treatments can have serious side effects, patients need to be carefully monitored. Once a patient’s pemphigus foliaceus is under control, and there are no active skin lesions for several months, doctors may start to gradually decrease the amount of immune-suppressing medication. Clinical examinations, as well as tests like ELISA-Dsg1 values or negative immunofluorescence, can help doctors decide when it’s safe to discontinue therapy.
What else can Pemphigus Foliaceus be?
When a doctor is attempting to confirm a diagnosis, they consider several similar conditions to make sure they get it right. In this case, they might consider whether the patient condition could instead be:
- Another type of pemphigus (a group of skin disorders)
- Bullous impetigo (a contagious skin infection)
- Subcorneal pustular dermatosis (a skin disorder characterized by pustules)
- Subacute cutaneous lupus erythematosus (a type of lupus that affects the skin)
- Seborrheic dermatitis (a common skin condition causing scaly patches, red skin, and stubborn dandruff)
An essential step to confirm if the patient’s condition is a form of pemphigus involves detecting certain autoantibodies (a type of protein produced by the immune system) against the skin’s surfaces.
What to expect with Pemphigus Foliaceus
Pemphigus foliaceus is considered a mild disease that often reacts positively to treatments and can potentially disappear completely. On the other hand, pemphigus erythematosus, a different type of the disease, can persist in a localized area for several years. However, its progression tends to resemble that of pemphigus foliaceus.
