Endemic, Drug-Induced, and Other Variants of PF

Pemphigus Foliaceus (PF) is not a “one-size-fits-all” condition. While the underlying science involves the same attack on the skin’s “glue” (desmoglein-1), the reason that attack starts can vary from person to person. Understanding which “type” of PF you have can help you and your doctor identify triggers and refine your management plan.

Medication as a Trigger: Drug-Induced PF

Sometimes, PF isn’t caused by an internal malfunction or an environmental factor, but by a reaction to a medication. This is known as Drug-Induced Pemphigus Foliaceus (DIPF).

The first and most important step for this variant is identifying and withdrawing the offending drug, which may lead to the skin clearing up without the need for long-term, heavy immunosuppressants ^[1]. Common trigger medications include:

• Thiol-containing drugs: Such as penicillamine (used for rheumatoid arthritis or Wilson’s disease) ^[2].
• ACE Inhibitors: Common blood pressure medications like enalapril or captopril ^[3].
• Other common drugs: Certain NSAIDs (pain relievers), calcium channel blockers (like amlodipine), and even some antibiotics ^[4].

Variations in How PF Appears

Doctors also classify PF based on how it looks and how much of the body it covers.

• Localized/Dermatomal: In some cases, the crusting stays in one specific area, such as just the scalp or a small patch on the chest ^[5].
• Pemphigus Erythematosus (Senear-Usher Syndrome): This is a localized variant of PF that often presents on the face (across the cheeks and nose) and can resemble the rash of lupus. It often combines features of both pemphigus and lupus ^[6].
• Erythrodermic: This is a severe form where the disease spreads to cover almost the entire body. The skin becomes intensely red, hot, and scaly ^[7].

Geography and the Environment: “Fogo Selvagem”

Note: This specific variant is strictly geographic. If you live in the United States, Europe, or other non-endemic regions, everyday insect bites will not cause PF.

In most of the world, PF is a “sporadic” disease, meaning it happens randomly. However, in certain parts of the world, PF is endemic—it occurs frequently in specific geographic clusters. This variant is known as Fogo Selvagem, which is the Portuguese name for “wild fire,” used in Brazil to describe the burning sensation on the skin ^[8].

This variant is found mostly in rural areas of South America (like Brazil and Colombia) and North Africa (Tunisia) ^[9][10]. Research suggests it is triggered by bites from the Simuliidae black fly ^[11]. It is believed that proteins in the fly’s saliva may trick the immune systems of genetically susceptible people into attacking their own skin ^[9].

Other Environmental Triggers

Even after a diagnosis, your environment can continue to influence how “active” your PF is.

• Ultraviolet (UV) Light: Sun exposure is a major trigger for many PF patients ^[12]. It can cause stable skin to flare up or localized patches to spread ^[13].
• Vaccines and Infections: While rare, some case reports note PF flare-ups shortly after a viral infection or a vaccination, including COVID-19 vaccines ^[14][15]. These triggers don’t “cause” the disease in everyone, but can act as a stressor ^[16]. Importantly, dermatology guidelines still strongly recommend vaccinations for autoimmune patients. Because treatments for PF suppress the immune system, patients are at a high risk for severe complications from infections. The protective benefits of vaccines far outweigh the rare risk of a flare. Always discuss the optimal timing of vaccines with your doctor.