Pemphigus is a group of rare autoimmune blistering diseases in which the immune system produces antibodies that attack proteins holding skin cells together, causing painful blisters and erosions on the skin and mucous membranes. Left untreated, pemphigus was historically fatal; modern immunosuppressive therapy has changed that dramatically, though the disease remains serious and chronic. The biology, the clinical subtypes, and the rapidly evolving treatment landscape are all more nuanced than a single label suggests.
What Goes Wrong in the Skin
Your skin cells stick together through specialized structures called desmosomes, and the key molecular glue inside desmosomes is a family of adhesion proteins, the desmogleins. In pemphigus, the immune system generates autoantibodies that target desmoglein 1 (found mainly in the upper layers of the skin) and desmoglein 3 (concentrated in deeper layers and in mucous membranes). When these antibodies latch onto desmogleins, they disrupt cell-to-cell adhesion, and the skin cells literally come apart from one another. Researchers have shown that pemphigus vulgaris autoantibodies directly block desmoglein 3 from binding to its partners on neighboring cells, which is a central event in blister formation.1PubMed Central. Peptides Targeting the Desmoglein 3 Adhesive Interface Prevent Autoantibody-induced Acantholysis in Pemphigus More recent work has demonstrated that autoantibodies in both pemphigus vulgaris and pemphigus foliaceus also block the binding between desmogleins and another adhesion partner called desmocollin, broadening the picture of how the adhesion failure occurs.2PubMed. Pemphigus Vulgaris and Foliaceus IgG Autoantibodies Directly Block Heterophilic Transinteraction between Desmoglein and Desmocollin
There is an ongoing scientific debate about whether antibodies cause damage purely by physically blocking adhesion (steric hindrance) or whether they also trigger signaling pathways inside the cell that weaken desmosomes from within. Studies on pemphigus foliaceus have found evidence that autoantibodies can destabilize cell junctions without directly blocking desmoglein 1 binding, pointing toward intracellular signaling as an additional mechanism.3PubMed Central. Pemphigus foliaceus IgG causes dissociation of desmoglein 1-containing junctions without blocking desmoglein 1 transinteraction In practice, both pathways likely contribute, and the relative importance may differ between pemphigus subtypes.
Types of Pemphigus
Pemphigus Vulgaris
Pemphigus vulgaris (PV) is the most common form and the one most people mean when they say “pemphigus.” It typically starts with painful sores in the mouth that refuse to heal, sometimes months before any skin blisters appear. This progression tracks with the antibody profile: when only anti-desmoglein 3 antibodies are present, the disease stays confined to mucous membranes. When anti-desmoglein 1 antibodies develop as well, blisters spread to the skin.4PubMed. The clinical phenotype of pemphigus is defined by the anti-desmoglein autoantibody profile Researchers have documented individual patients whose disease evolved from pure mucosal involvement to generalized skin-and-mucosa disease, and this transition coincided exactly with the appearance of anti-desmoglein 1 antibodies in their blood.5PubMed. Mucosal and mucocutaneous (generalized) pemphigus vulgaris show distinct autoantibody profiles The blisters in PV are fragile and rupture easily, leaving raw, painful erosions that heal slowly.
Pemphigus Foliaceus
Pemphigus foliaceus (PF) involves only anti-desmoglein 1 antibodies, so it affects the superficial skin layers and spares the mucous membranes. Instead of the deep, weeping erosions of PV, PF tends to produce scaly, crusted lesions that can look like eczema or a bad sunburn. Because desmoglein 1 is most densely concentrated in the upper epidermis, PF blisters are so superficial they often break before a patient even notices them, leaving behind flaky patches on the scalp, face, chest, and upper back.
An endemic form called fogo selvagem (“wild fire”) occurs in rural Brazil and certain other regions of South America. Its cause is thought to be multifactorial, involving a genetic predisposition combined with environmental exposure. The geographic clustering of cases near rivers and within the flight range of black flies has led researchers to hypothesize that bites from the fly species Simulium pruinosum may trigger the autoimmune response in genetically susceptible individuals.6PubMed. Endemic pemphigus foliaceus (Fogo Selvagem): II. Current and historic epidemiologic studies This endemic form otherwise looks and behaves like ordinary PF, and the same anti-desmoglein 1 antibodies are found in affected patients.7PubMed Central. Fogo selvagem: endemic pemphigus foliaceus
Paraneoplastic Pemphigus
Paraneoplastic pemphigus (PNP) is the rarest and most dangerous subtype. It occurs in the setting of an underlying cancer and produces severe, painful erosions of the mouth and lips along with variable skin lesions that can mimic other blistering diseases. PNP is most commonly linked to blood cancers: non-Hodgkin lymphoma accounts for roughly 39–45% of associated tumors, followed by chronic lymphocytic leukemia and Castleman disease.8Anais Brasileiros de Dermatologia. Paraneoplastic pemphigus: a clinical, laboratorial, and therapeutic overview In children and adolescents, Castleman disease is the tumor most frequently seen alongside PNP. Solid tumors make up a smaller share of cases. The prognosis for PNP is generally worse than for other pemphigus types, partly because the underlying malignancy itself carries risk and partly because PNP can involve the lungs, causing a sometimes-fatal bronchiolitis obliterans.9PubMed. Paraneoplastic Pemphigus and Autoimmune Blistering Diseases Associated with Neoplasm: Characteristics, Diagnosis, Associated Neoplasms, Proposed Pathogenesis, Treatment
Drug-Induced Pemphigus
Certain medications can trigger pemphigus in susceptible individuals. The drugs most commonly implicated are thiol-containing compounds such as penicillamine, captopril, and bucillamine, but a growing list of non-thiol medications has also been linked to the disease.10PubMed Central. Drug-Induced Pemphigus Foliaceus Potentially Triggered by Piperacillin-Tazobactam, Linezolid, and Additional Factors: A Report of a Rare Case A systematic review of 170 patients with drug-induced pemphigus found that PV and PF were the most common presentations, and penicillamine was by far the most frequently reported culprit, associated with about a third of cases and with the most persistent disease.11PubMed. Drug-induced pemphigus: A systematic review of 170 patients The disease often improves after the offending drug is stopped, though some patients go on to develop persistent autoimmune pemphigus regardless.
Who Gets Pemphigus
Pemphigus can strike anyone, but it shows strong ethnic and geographic patterns. Incidence varies widely across populations. A study in Israel found an overall incidence of about 7.2 cases per million people per year, but the rate in the Jewish population was threefold higher than in Arab residents of the same region, and women were affected more often than men.12PubMed. Remarkable differences in the epidemiology of pemphigus among two ethnic populations in the same geographic region Populations of Ashkenazi Jewish, South Asian, and Mediterranean descent tend to have higher rates, while pemphigus is less common in northern European and East Asian groups.
Genetic susceptibility is strongly tied to the HLA system, the set of genes that helps your immune system distinguish self from non-self. Specific HLA variants have been linked to different pemphigus subtypes. For pemphigus vulgaris, variants including DRB1*0402 and DQB1*0503 are consistently associated with increased risk, while different HLA variants have been linked to pemphigus foliaceus.13PubMed. HLA class II polymorphism contributes to specify desmoglein derived peptides in pemphigus vulgaris and pemphigus foliaceus Carrying these HLA types doesn’t mean you will develop pemphigus; it means your immune system is more likely to present desmoglein fragments in a way that can activate an autoimmune response. Most people with “susceptibility” HLA types never develop the disease, which is why researchers suspect that environmental triggers are also needed.
Thiol-containing foods and compounds have drawn attention as possible environmental triggers. A case-control study found that daily consumption of foods rich in thiol groups, including leeks, tomatoes, and mustard oil, was associated with significantly higher odds of developing pemphigus vulgaris.14PubMed Central. Environmental triggers of pemphigus vulgaris and bullous pemphigoid: a case control study These dietary associations remain tentative and don’t establish causation, but they fit into a broader pattern where thiol-containing substances, whether drugs or foods, seem to stress the desmoglein system.
How Pemphigus Is Diagnosed
Diagnosis rests on three pillars: what the lesions look like, what the tissue shows under special staining, and what antibodies are circulating in the blood. Clinically, pemphigus should be suspected whenever a patient has persistent oral erosions that don’t respond to standard treatments, fragile blisters that rupture easily, or a positive Nikolsky sign (where gentle lateral pressure on normal-looking skin causes it to shear off).
A skin biopsy examined with direct immunofluorescence (DIF) is the gold standard. DIF detects antibodies bound directly within the tissue, typically showing a characteristic “chicken wire” or “fishnet” pattern of IgG deposited between skin cells. In one cross-sectional study, DIF had a sensitivity of about 94% for pemphigus, meaning it correctly identifies the disease in the vast majority of cases.15PubMed Central. A Cross-sectional Study of Direct Immunofluorescence in the Diagnosis of Immunobullous Dermatoses Indirect immunofluorescence, which tests the patient’s serum against a tissue substrate, and ELISA tests that measure specific anti-desmoglein 1 and anti-desmoglein 3 antibody levels provide additional confirmation and help classify the subtype.16PubMed Central. Utility of immunofluorescence in dermatology
ELISA testing has become especially useful for tracking disease activity over time, not just for initial diagnosis. In longitudinal studies, desmoglein ELISA values rose and fell in parallel with disease flares and remissions, and ELISA proved more reliable for monitoring than older indirect immunofluorescence titers.17PubMed Central. Detection of serum desmoglein antibody level using enzyme-linked immunosorbent assay (ELISA) for monitoring disease activity in patients with pemphigus vulgaris That said, antibody levels don’t always predict severity neatly. One study found a significant correlation between initial antibody titers and mucosal scores, but no consistent relationship between antibody levels and skin severity at later time points.18PubMed Central. Assessing the Autoantibody Levels in Relation to Disease Severity and Therapy Response in Pemphigus Patients In other words, blood tests help guide treatment decisions but don’t replace the clinical picture.
Treatment With Corticosteroids and Steroid-Sparing Agents
For decades, high-dose corticosteroids (usually prednisone or prednisolone) have been the first-line treatment. A typical starting dose for pemphigus vulgaris is around 1 mg per kilogram of body weight per day, sometimes higher for severe cases.19Clinical & Experimental Dermatology and Therapies. Alternate-Day Corticosteroid Therapy in Pemphigus Vulgaris and Bullous Pemphigoid Steroids suppress the immune system broadly and can bring pemphigus under control, but the doses required and the duration of treatment expose patients to serious side effects: bone loss, diabetes, weight gain, cataracts, and increased vulnerability to infections. In extreme cases, the complications of steroid therapy can be fatal; one case report documented a patient who died of pulmonary embolism after steroid doses were escalated to control refractory disease.20PubMed. Pemphigus vulgaris and complications of systemic corticosteroid therapy: a case report
Because of these risks, steroid-sparing immunosuppressants are added as soon as possible. The two most commonly used are azathioprine and mycophenolate mofetil.21PubMed Central. Management of pemphigus vulgaris: challenges and solutions Both work by tamping down the overactive immune response through different pathways, allowing doctors to taper steroids more quickly. A retrospective comparison found that patients on mycophenolate mofetil achieved complete remission faster than those on azathioprine (a median of about 7 months versus 12.5 months) and required lower cumulative steroid doses.22PubMed Central. A Comparison of Azathioprine and Mycophenolate Mofetil as Adjuvant Drugs in Patients with Pemphigus: A Retrospective Cohort Study Even with these agents, many patients face a long road of treatment adjustments and relapses.
Rituximab’s Rise as a First-Line Option
The biggest shift in pemphigus treatment in recent years has been the emergence of rituximab, a drug that targets and depletes a subset of immune cells called B lymphocytes, which are the cells responsible for producing the pathogenic autoantibodies. A landmark randomized trial compared rituximab plus a short course of prednisone against prednisone alone in newly diagnosed pemphigus patients. At 24 months, 89% of patients in the rituximab group were in complete remission off therapy, compared with 34% in the prednisone-alone group. The rituximab group also experienced fewer severe side effects.23The Lancet. Rituximab plus Prednisone versus Prednisone Alone in First-Line Pemphigus
Head-to-head data against other steroid-sparing agents have reinforced rituximab’s advantage. In a trial comparing rituximab to mycophenolate mofetil, 40% of rituximab patients achieved sustained complete remission at one year versus 10% on mycophenolate.24PubMed. Rituximab versus Mycophenolate Mofetil in Patients with Pemphigus Vulgaris A network meta-analysis found that rituximab reduced cumulative steroid exposure more than any other adjuvant, cutting it by nearly 12,000 mg of glucocorticoid equivalents compared with steroids alone.25PubMed. Network meta-analysis-based comparison of first-line steroid-sparing adjuvants in the treatment of pemphigus vulgaris and pemphigus foliaceus
Repeated courses of rituximab appear to work as well or better than the first. Studies of patients receiving second and third courses report complete remission rates of 75–81%, with each subsequent course tending to produce longer remissions and fewer flare-ups, suggesting that rituximab acts as a genuine disease-modifying agent rather than just a temporary fix.26PubMed Central. Efficacy of Repeated Courses of Rituximab as Treatment for Pemphigus Vulgaris Based on this evidence, rituximab is now approved in the EU and the US for moderate-to-severe pemphigus vulgaris and is increasingly used as a first-line therapy alongside a short steroid course rather than reserved for refractory cases.27PubMed. Rituximab: A Review in Pemphigus Vulgaris
For patients who don’t respond to rituximab, intravenous immunoglobulin (IVIg) has shown benefit. In one small series, patients with severe pemphigus who remained resistant to both immunoadsorption and rituximab achieved a good response with IVIg therapy.28British Journal of Dermatology. Treatment of severe pemphigus with protein A immunoadsorption, rituximab and intravenous immunoglobulins
Therapies on the Horizon
Two emerging approaches could change the treatment landscape further. The first targets the neonatal Fc receptor (FcRn), a molecule that protects IgG antibodies from being broken down, keeping them circulating in the blood for weeks. Drugs that block FcRn speed up the clearance of all IgG, including the pathogenic autoantibodies, without directly suppressing immune cells.29PubMed Central. FcRn Inhibition in Autoantibody-Mediated Autoimmune Diseases: From Broad Immunosuppression to Precision IgG Modulation Efgartigimod, one such FcRn inhibitor, showed rapid results in a phase II trial: 90% of pemphigus patients achieved early disease control after a median of 17 days, whether used alone or with a low dose of prednisone.30British Journal of Dermatology. Treatment of pemphigus vulgaris and foliaceus with efgartigimod, a neonatal Fc receptor inhibitor: a phase II multicentre, open‐label feasibility trial Larger confirmatory trials are ongoing.
The second and more radical approach borrows from cancer immunotherapy. Chimeric autoantibody receptor T cells (CAAR-T cells) are engineered T cells that display desmoglein 3 on their surface. When a B cell that makes anti-desmoglein 3 antibodies encounters the CAAR-T cell, it binds to the displayed desmoglein and the T cell destroys it. In preclinical studies, these engineered cells specifically killed anti-desmoglein 3 B cells from pemphigus patients while leaving other B cells untouched.31PubMed Central. Reengineering chimeric antigen receptor T cells for targeted therapy of autoimmune disease Follow-up preclinical work demonstrated that CAAR-T cells could engraft, persist, and reduce both target B cells and circulating autoantibodies in vivo, laying the groundwork for the first human trials.32JCI Insight. Antigen-specific B cell depletion for precision therapy of mucosal pemphigus vulgaris If this approach works in people, it would represent a true precision therapy: eliminating only the disease-causing immune cells without the broad immunosuppression of current treatments.
Infections and the Real Cost of Immunosuppression
The biggest day-to-day danger for someone living with pemphigus isn’t the blisters themselves but the infections that thrive in open wounds and immunosuppressed bodies. An analysis of hospital admissions in the United States found that about half of pemphigus inpatients had a serious infection, roughly double the rate seen in hospital patients without the disease. Pemphigus patients faced higher rates of skin infections, respiratory infections, sepsis, and antibiotic-resistant infections, and were specifically more susceptible to opportunistic pathogens. Among pemphigus inpatients, those who developed a serious infection had an in-hospital death rate of nearly 7%, compared with under 2% for pemphigus patients without infection.33PubMed. Association of serious infections with pemphigus and pemphigoid: analysis of the Nationwide Inpatient Sample
This underscores why the push toward steroid-sparing and more targeted therapies matters so much. Every milligram of steroid avoided is a step toward preserving the patient’s ability to fight ordinary infections. It also explains why dermatologists increasingly reach for rituximab early, before years of high-dose steroids have taken their toll.
Pemphigus in Cats and Dogs
Pemphigus is not exclusively a human disease. Pemphigus foliaceus is the most common autoimmune skin disease in cats and dogs, and it bears real similarities to the human version: autoantibodies attack desmoglein-family proteins, and the result is crusting, blistering skin disease. In cats, PF typically shows up as crusts and erosions on the face and feet, and more than half of affected cats also develop lethargy, fever, or loss of appetite. The good news for cat owners is that the prognosis is generally favorable, with most cats responding well to steroid therapy alone, though long-term treatment is usually required and relapses are common.34PubMed Central. Feline pemphigus foliaceus: original case series and a comprehensive literature review The existence of pemphigus across species reinforces that these adhesion proteins and the autoimmune vulnerabilities they carry are deeply conserved in biology, not quirks of human immunology.