Fogo Selvagem - An Overview

Introduction:

Fogo selvagem is an autoimmune disease that is organ-specific and is characterized by blister formation. Individuals with fogo selvagem show positive Nikolsky’s sign, which means the affected skin starts blistering when rubbed against something. Dr. Piotr Nikolsky initially identified this sign. Fogo selvagem is an endemic variant of pemphigus foliaceus , which was previously known as Brazilian pemphigus foliaceus as it was first discovered in particular river valleys in Brazil. The outlook for individuals with fogo selvagem is favorable with proper treatment. The majority of patients do well.

What Is Fogo Selvagem?

Fogo selvagem, also known as endemic pemphigus foliaceus, is an autoimmune bullous disease. It is a variation of pemphigus foliaceus with a distinctive epidemiological profile. This condition mainly affects the seborrheic areas. The term pemphigus refers to a class of cutaneous illnesses clinically characterized by blisters, acantholysis (keratinocyte detachment), and skin or mucous membrane erosions. Endemic pemphigus foliaceus is prevalent in Brazil, where it is referred to as fogo selvagem. Fogo selvagem is a Portuguese phrase that translates to wildfire.

Who Is Affected by Fogo Selvagem?

• Fogo selvagem is a rare condition globally, with an annual incidence of 0.76 to 5 new cases per million people worldwide.

• The rural areas of Brazil's southern and midwestern states, including Goiás, Mato Grosso do Sul, Paraná, So Paulo, and Minas Gerais, are where fogo selvagem is most common. Additionally, cases have been documented in Colombia, Paraguay, El Salvador, Peru, Tunisia, and Peru.

• Fogo selvagem is prevalent among children and young adults.

• The prevalence of fogo selvagem is higher in places near rivers and streams and is closely related to poverty and malnutrition.

• Fogo selvagem is linked to the human leukocyte antigen complex, suggesting a genetic predisposition to the condition.

• Fogo selvagem affects both genders and all races equally.

What Causes Fogo Selvagem?

Although the exact pathophysiology of fogo selvagem is unknown, it is believed that a combination of genetic and environmental factors is at play. The causes of fogo selvagem include the following:

• Immune Response: Fogo selvagem is an autoimmune condition which means the affected person's immune system starts attacking the body's healthy cells. In fogo selvagem, the immune system starts reacting against the keratinocytes and desmosomes of the skin. The body makes immunoglobulin G4 antibodies, which bind to the desmosomal protein in response to fogo selvagem. The surface keratinocytes of the epidermis get detached from one another and fill with fluid, producing blisters.

• Genetic Factors: Fogo selvagem can occur in up to 20 percent of genetically linked family members. Patients with fogo selvagem have the expression of the HLA-DRB1-0404, 1402, or 1406 alleles, which suggests a genetic predisposition.

• Black Fly: The autoimmune reaction is thought to be triggered by a salivary protein from a blood-sucking bug like the black fly because individuals with fogo selvagem have been observed to experience black fly bites more frequently.

• Drugs: D-penicillamine and Captopril are the two most commonly prescribed medications that can cause pemphigus foliaceus.

What Are the Symptoms of Fogo Selvagem?

Common signs and symptoms of fogo selvagem are:

• Surface vesicles or blisters that develop over weeks to months.

• Blisters and lesions that are prone to rupture when the skin is touched.

• Erosion and crusting on the seborrheic areas, such as the head, face, neck, and upper trunk.

• Burning sensation.

• Redness of the skin.

What Are the Complications of Fogo Selvagem?

Complications of untreated fogo selvagem include:

• Growth delay in children.

• Dwarfism.

• Infertility in men (azoospermia).

• Increased susceptibility to viral infections.

What Is the Differential Diagnosis of Fogo Selvagem?

Conditions with similar symptoms that should be considered as the differential diagnosis of fogo selvagem are:

• Seborrheic dermatitis (a skin disease that primarily affects the scalp and generates red skin and scaly patches.).

• Cutaneous lupus erythematosus (an autoimmune disease affecting the skin).

• Pemphigus vulgaris (an autoimmune disease that causes blistering of the skin and the mucus membrane).

• Psoriasis (It is a skin condition that typically affects the knees, elbows, trunk, and scalp. It causes a rash with itchy, scaly spots.).

• Atopic dermatitis (eczema or atopic dermatitis results in dry, itchy, and irritated skin.).

How Is Fogo Selvagem Diagnosed?

• The presence of the disease in the area, the presence of the disease's distinctive blisters, and a positive Nikolsky sign all contribute to the diagnosis of fogo selvagem. Positive Nikolsky’s sign refers to blisters developing when the affected skin is lightly rubbed.

• A skin biopsy report reveals acantholysis of the top epidermis, which frequently results in a subcorneal cleft and occurs when keratinocytes lose their ability to adhere to one another, causing the skin layer to split. The subcorneal cleft widens and has the potential to separate, either with or without bulla development.

• Parakeratosis, hyperkeratosis, and papillomatosis are examples of other histological abnormalities. There could be a little lymphocytic infiltration as well.

• Intercellular fluorescence in the epidermis is visible with direct immunofluorescence.

• Intercellular fogo selvagem autoantibodies can be found using an ELISA (enzyme-linked immunosorbent assay) test.

How Is Fogo Selvagem Treated?

The preferred treatment for people with severe fogo selvagem is systemic corticosteroid therapy. Because of the lower morbidity and fatality rates than pemphigus vulgaris, therapy for fogo selvagem is typically less aggressive. Topical glucocorticoids may be sufficient in people with minimal symptoms.

Systemic corticosteroids, such as Prednisone or Prednisolone, are used to treat fogo selvagem, and most patients respond well. Moreover, other drugs may include; Azathioprine, Mycophenolate, Cyclophosphamide, etc. Prednisone (1 mg per kg body weight) is given as a single morning dose until blister production stops or the Nikolsky sign goes away.

After primary control is attained, the prednisone dose is reduced. The dosage is reduced to half the initial dose. This tapering in dosage is done until a minimum effective maintenance dose is achieved. The reduction in the dosage is made over weeks to months.

Conclusion:

Fogo selvagem is a rare condition and typically has a good prognosis with proper treatment. The majority of patients do well. The traits of stunted growth and widespread skin exfoliation in young individuals with fogo selvagem are remarkable. Growth is halted in patients who have poorly managed fogo selvagem.