What Causes Granuloma Annulare? 

June 1st, 2026

Key takeaways

• Granuloma annulare (GA) is best understood as a benign inflammatory reaction pattern rather than a skin disease with one single established cause. Its exact etiology remains uncertain.  
• Current evidence supports an immune-mediated pathogenesis involving macrophages, T cells, and cytokine signaling, with granulomatous inflammation and dermal collagen alteration as central features.  
• A range of triggers and associations have been reported, including minor trauma, insect bites, sun exposure, medications, systemic disease, and infections, but most of these are inconsistent and do not prove causation.  
• Viral infections linked to GA in the literature include human immunodeficiency virus (HIV), Epstein-Barr virus, and varicella zoster virus, although these are better framed as possible triggers or associations instead of universal causes.  
• For most patients with classic localized GA, extensive systemic workup is not routinely required. Evaluation should be guided by morphology, distribution, chronicity, and the presence of atypical or generalized disease.  

Defining the question: What do clinicians mean by ‘cause’?

When patients ask what causes GA, they usually are asking for a simple explanation. Clinically, the answer is more nuanced. GA does not have one confirmed cause in the way ringworm (tinea corporis) has a fungal cause or scabies has a mite cause. Instead, it is more accurate to describe GA as a cutaneous inflammatory reaction pattern that can arise spontaneously or in the setting of multiple proposed triggers.  

That distinction matters. Much of the literature on GA discusses associations, triggers, and pathophysiology rather than definitive causation. For clinicians, the practical task is not to identify a single root cause in every patient, but to recognize when GA likely is idiopathic and when the presentation should prompt a closer search for contributing factors.  

The leading explanation: An immune-mediated granulomatous process

The most widely accepted explanation is that GA reflects an immune-mediated granulomatous inflammatory response in the skin. Reviews describe involvement of T-cell signaling, macrophage activation, and cytokine pathways that contribute to collagen degeneration and granuloma formation.  

This helps explain why GA is grouped with granulomatous dermatoses and why its histology often shows palisading or interstitial granulomatous inflammation. It also helps explain why anti-inflammatory and immunomodulatory therapies, rather than anti-infective therapy, are the mainstay when treatment is needed.  

In practical terms, the current model is that GA occurs when an immune response in the dermis becomes dysregulated enough to generate a recognizable annular granulomatous eruption. What initiates that immune response likely differs from patient to patient.  

Idiopathic disease is common

In many patients, no trigger is identified. That is especially true in classic localized GA, which often appears in otherwise healthy individuals and may resolve spontaneously over time.  

This is an important counseling point. Patients often assume a ring-shaped eruption must reflect infection, allergy, or a dangerous internal disorder. In most cases of localized GA, there is no single explanation that can be confidently assigned, and that uncertainty is built into the disease itself.  

Reported minor skin injury and environmental triggers

GA has been reported after local trauma, insect bites, and sun exposure. These observations support the idea that cutaneous injury or inflammation may trigger a granulomatous response in susceptible patients.  

These triggers are plausible, but they are not consistent enough to be predictive. Most patients cannot identify a clear inciting event, and many people experience these exposures without ever developing GA.  

Medications

Drug-associated GA has been described, although the evidence is based largely on case reports and series. Reviews have reported medication links without establishing a uniform high-risk drug class across all studies.  

That means medication review is reasonable in atypical, generalized, or temporally suspicious cases, but clinicians should avoid overstating causality when the evidence is weak or when multiple alternative explanations exist.  

Infections, including viral infections

Infectious triggers for GA have long been proposed. Viral associations reported in the literature include HIV, Epstein-Barr virus, and varicella zoster virus. Some publications also discuss hepatitis viruses and, more recently, SARS-CoV-2-related cases, but these data are limited and do not establish a uniform causal pathway.  

Among infectious associations, HIV is the one most likely to alter clinical decision-making, especially when GA is generalized, atypical, or treatment-refractory. By contrast, Epstein-Barr virus and varicella zoster virus are better understood as reported triggers than as targets for routine testing in every patient with classic disease.  

Systemic disease associations

GA has been linked in some studies to diabetes, dyslipidemia, thyroid disease, and malignancy, but the evidence is mixed. The Mayo Clinic notes that diabetes and thyroid disease are more often discussed in patients with widespread disease. Cancer association is described as uncommon and more relevant in severe or treatment-resistant cases, or in cases involving older patients.  

More recent epidemiologic work has continued to explore malignancy and autoimmune associations, but the literature remains heterogeneous and should not be interpreted as proving that GA usually reflects occult systemic disease. 

What most likely does not cause granuloma annulare

One of the most useful clinical clarifications is what GA is not.

GA is not a fungal infection. It may resemble ringworm because both can produce annular lesions, but GA is not caused by dermatophytes and is not contagious.  

GA also is not well explained by poor hygiene, food contamination, or routine allergic exposure. Patients frequently look for a simple lifestyle cause, but the literature supports an inflammatory pathogenesis far more than a hygiene-based or dietary explanation.  

Cause vs. association: A practical matrix 

Category	What the literature suggests	How clinicians should interpret it
Immune dysregulation	Strongest current explanation for pathogenesis	Best viewed as core disease mechanism rather than an external trigger
Trauma, bites, sun exposure	Repeatedly reported as possible triggers	Plausible in individual cases, but not consistent enough to be predictive
Medications	Reported in case-based literature	Review medication timeline in suspicious cases; avoid overcalling causality
Viral and other infections	Reported associations include human immunodeficiency virus, Epstein-Barr virus, varicella zoster virus, and others	Consider as possible triggers, especially in atypical or generalized granuloma annulare (GA)
Diabetes, thyroid disease, dyslipidemia	Commonly discussed associations, especially with generalized disease	Consider targeted evaluation when clinical context supports it
Malignancy	Rare, debated, and likely overgeneralized if applied broadly	More relevant in older adults with severe, atypical, or refractory disease
Idiopathic disease	Very common, especially in localized GA	Often the most accurate conclusion in routine practice

Does generalized granuloma annulare have different implications?

Yes. Generalized GA is more likely than localized GA to trigger questions about underlying associations, partly because it is more persistent and more often discussed in connection with systemic conditions in the literature.  

That does not mean generalized GA always has an identifiable cause. It means the threshold for reviewing medications, considering targeted laboratory evaluation, and assessing for relevant infectious or systemic clues is lower than it is for a patient with a few classic lesions on the dorsal hand.  

When should clinicians investigate further?

Most classic localized cases do not justify a broad search for an underlying cause. A more focused evaluation is reasonable when GA is generalized, atypical in morphology, unusually severe, treatment-resistant, recurrent in a concerning pattern, or accompanied by systemic symptoms or history that suggests infection, endocrine disease, autoimmunity, or malignancy.  

This is where clinical judgment matters most. The literature supports targeted workup more than routine blanket screening. For example, widespread disease in a patient with risk factors may justify diabetes or thyroid evaluation, while generalized or atypical disease with relevant exposure history may justify HIV testing.  

How to explain the cause of granuloma annulare to patients

A practical way to explain GA is this: It is an inflammatory skin condition in which the immune system creates ring-shaped or papular lesions in the skin, but in most people no single outside cause is found. Sometimes it appears after a trigger such as skin injury, illness, or medication exposure, and sometimes it appears without a clear reason.  

That explanation is accurate, reassuring, and less misleading than telling patients that GA is caused by fungus, infection, or a systemic disease unless the case truly supports one of those conclusions.  

Bottom line

The cause of granuloma annulare still is not fully known. The strongest current evidence points to an immune-mediated granulomatous process, although trauma, medications, infections, and systemic disease remain possible triggers or associations rather than universal explanations. In everyday practice, localized GA often is idiopathic. Generalized or atypical GA deserves a more deliberate review of possible contributors, but clinicians should be careful not to overpromise a single cause when the evidence does not support one.  

FAQ

What is the main cause of granuloma annulare?

There is no single confirmed main cause of granuloma annulare (GA). The best current explanation is an immune-mediated granulomatous inflammatory process in the skin.  

Is GA caused by stress?

Stress is not established as a primary cause of GA in the medical literature. Patients may report flares during stressful periods, but the core evidence supports immune dysregulation rather than stress as a direct proven cause.  

What viral infections are associated with GA?

Reported viral associations include human immunodeficiency virus (HIV), Epstein-Barr virus, and varicella zoster virus. These are best described as possible triggers or associations rather than definitive causes of GA in most patients.  

Is GA related to diabetes?

It can be associated with diabetes in some patients, particularly in generalized disease, but the relationship is not consistent enough to say diabetes causes GA in most cases.  

Can medications cause GA?

Medication-associated GA has been reported, but the evidence is mostly case-based. A medication may be a plausible trigger in some patients, although causality often is difficult to prove.  

Does GA mean the patient has cancer?

Usually, no. Malignancy has been discussed as a rare association, particularly in severe, atypical, or treatment-resistant cases, but most patients with GA do not have an occult cancer driving the eruption.  

Should every patient with GA get a broad laboratory workup?

No. Most patients with classic localized GA do not need broad screening. Workup should be targeted to generalized disease, atypical features, treatment resistance, or a history that suggests a relevant associated condition.