Furrowing in the esophagus, the appearance of vertical grooves or ridges running along the inner lining, is overwhelmingly caused by eosinophilic esophagitis (EoE), a chronic allergic condition in which a specific type of white blood cell accumulates in tissue where it does not normally belong. When a doctor sees furrows during an endoscopy, EoE is the leading suspect, though the story behind those grooves involves a surprisingly complex interplay of immune signaling, genetics, and environmental triggers that researchers are still piecing together.
Eosinophilic Esophagitis and the Furrowed Esophagus
EoE is a chronic, immune-driven disease that affects both children and adults. The hallmark is an infiltration of eosinophils into the lining of the esophagus, the muscular tube that carries food from your throat to your stomach. Eosinophils are white blood cells that normally help fight parasitic infections, but in EoE they show up in the wrong place, accumulating in tissue that should have almost none of them. Their presence triggers inflammation and physical changes to the esophageal wall, and one of the most recognizable of those changes is longitudinal furrowing.
During endoscopy, doctors look for a cluster of visual findings that together suggest EoE. These include mucosal fragility, ring-like ridges (sometimes called “felinization” because the ringed pattern resembles a cat’s esophagus), whitish plaques, swelling, and longitudinal furrows.1PubMed Central. An overview of eosinophilic esophagitis Furrows specifically have been shown to be a highly accurate marker of active disease. In one study of children with confirmed EoE, furrows had a sensitivity of about 89% and a specificity of about 90% for identifying active eosinophilic inflammation, meaning they are both commonly present when the disease is active and rarely present when it is not.2PubMed Central. Eosinophilic Esophagitis Reference Score Accurately Identifies Disease Activity and Treatment Effects in Children
The appearance of furrows is graded on a scale during endoscopy. Mild furrows are visible grooves without real depth, while severe furrows show visible depth or indentation into the mucosal surface.3Clinical Gastroenterology and Hepatology. Accuracy of the Eosinophilic Esophagitis Endoscopic Reference Score in Diagnosis and Determining Response to Treatment In practical terms, deeper furrows tend to indicate more severe or longer-standing inflammation. The grading system helps clinicians track whether a treatment is working, since furrows that flatten after therapy suggest the inflammation is resolving.
The Immune Cascade That Drives the Damage
Furrows do not just appear randomly. They are the visible result of an immune process gone awry. In EoE, the esophageal lining becomes a battleground for a type of immune response called a Th2 response, the same branch of the immune system involved in allergies and asthma. Th2 immune cells release signaling molecules, particularly IL-4 and IL-13, that act on the cells lining the esophagus. These signals trigger the esophageal cells to produce a chemical called eotaxin-3, which acts as a homing beacon for eosinophils, drawing them out of the bloodstream and into the esophageal tissue.4PubMed. Th2 cytokine signaling through IL-4Rα increases eotaxin-3 secretion and tension in human esophageal smooth muscle
Research has shown that this eotaxin-3 pathway is central to how eosinophils accumulate. IL-4 binds to a receptor on esophageal cells and sets off a chain of events involving calcium release inside those cells, which in turn ramps up eotaxin-3 production.5PubMed Central. In Esophageal Squamous Cells From Eosinophilic Esophagitis Patients, Th2 Cytokines Increase Eotaxin-3 Secretion Through Effects on Intracellular Calcium and a Non-Gastric Proton Pump Studies of EoE patients have confirmed that this cooperation between Th2 immune cells and the eotaxin-3 signaling pathway is a defining feature of the disease.6PubMed. Interplay of adaptive th2 immunity with eotaxin-3/c-C chemokine receptor 3 in eosinophilic esophagitis
Once eosinophils arrive in the esophageal tissue, they release their own destructive proteins, causing direct tissue damage. The inflammation swells the lining, disrupts its normal smooth architecture, and produces the furrows visible on endoscopy. Think of it as the mucosal surface buckling under the pressure of swelling and immune activity.
How the Esophageal Barrier Breaks Down
A key piece of the furrowing puzzle is what happens to the esophageal lining itself. Healthy esophageal cells are knitted tightly together by a protein called desmoglein-1, which acts like molecular glue holding the surface barrier intact. In EoE, IL-13, one of the Th2 signaling molecules, directly suppresses desmoglein-1 production. When that glue weakens, cells begin to separate, and the barrier function of the esophagus breaks down.7PubMed. Desmoglein-1 regulates esophageal epithelial barrier function and immune responses in eosinophilic esophagitis
This impaired barrier matters beyond just creating furrows. When the esophageal lining becomes leaky, allergens and irritants that would normally stay on the surface can penetrate deeper, triggering even more immune activation. It creates a vicious cycle: inflammation damages the barrier, the weakened barrier lets more allergens in, and the immune system ramps up further. The furrows you see on endoscopy are the outward sign of this process running unchecked.
Genetic Susceptibility
Not everyone exposed to the same foods and allergens develops EoE, which points to a strong genetic component. Genome-wide studies have identified several gene regions linked to increased EoE risk. One early finding was the TSLP gene, which produces a molecule that helps initiate allergic immune responses. More recent research has turned up additional loci, including regions near genes called STAT6 and c11orf30, which have also been tied to other allergic and autoimmune conditions. Two other identified genes are more specific to EoE: ANKRD27, involved in moving proteins within cells, and CAPN14, which encodes a protein whose activity is particularly concentrated in esophageal tissue.8Nature Communications. GWAS identifies four novel eosinophilic esophagitis loci
The CAPN14 finding is especially interesting because it suggests that the esophagus has a unique biological vulnerability. While many allergic conditions share overlapping genetic risk factors, CAPN14 appears to be an esophagus-specific player, which may help explain why some people with widespread allergies develop problems specifically in this one organ. Genetic variation in these regions does not guarantee that someone will develop EoE, but it lowers the threshold, making them more susceptible when exposed to the right triggers.
Food and Environmental Triggers
EoE is fundamentally a reaction to something in the environment, and food allergens are the most common culprits. The foods most frequently implicated are milk, wheat, eggs, soy, nuts, and seafood, with milk and wheat being especially common triggers. EoE and classic food allergy share a significant overlap: both are food-triggered, both involve Th2 immune skewing, and both appear to relate to impaired barrier function that lets allergens interact with the immune system inappropriately.9PubMed Central. Triggers for eosinophilic esophagitis (EoE): The intersection of food allergy and EoE
But food is not the only trigger. Airborne allergens also play a role, which explains a curious pattern: some patients experience seasonal flares. A study examining both adults and children with EoE found that specific endoscopic findings, including edema and furrows, worsened significantly during pollen seasons compared to off-seasons. Furrow scores roughly quadrupled from low-pollen to high-pollen periods.10PubMed Central. Seasonal exacerbation of eosinophilic esophagitis histologic activity in adults and children implicates role of aeroallergens This seasonal pattern suggests that for some people, inhaled allergens like pollen can drive esophageal inflammation the same way food allergens do. If you have EoE and notice your swallowing difficulties worsen every spring, aeroallergens may be a contributing factor alongside any dietary triggers.
Is It Always EoE?
While EoE is far and away the most common cause of esophageal furrowing, it is not the only possibility. Distinguishing EoE from gastroesophageal reflux disease (GERD) has been a longstanding challenge, because both conditions can cause esophageal inflammation and some overlapping symptoms. Typical EoE patients tend to be younger, often male, and frequently have a history of allergies. They present with difficulty swallowing solid foods and sometimes food getting stuck in the esophagus. The endoscopic picture, with furrows, rings, white plaques, and tissue swelling, tends to look distinct from GERD, which more commonly causes erosions and redness concentrated at the bottom of the esophagus near the stomach.11PubMed Central. Distinguishing GERD from eosinophilic oesophagitis: concepts and controversies
Other rare conditions can occasionally produce furrows or furrow-like changes. Lymphocytic esophagitis, in which a different type of immune cell infiltrates the esophageal lining, can create similar-looking endoscopic findings. Certain medication-induced injuries to the esophagus and rare forms of esophagitis can also mimic the appearance. In practice, biopsy is the definitive step: finding a high concentration of eosinophils in the tissue confirms EoE, while finding predominantly lymphocytes or a different inflammatory pattern points elsewhere. If your endoscopy shows furrows but biopsy results are ambiguous, your gastroenterologist will likely factor in your symptom history, allergy profile, and response to initial treatments.
What Happens When Furrowing Goes Untreated
Furrows belong to a category of endoscopic findings that reflect active inflammation. But over time, chronic untreated EoE can progress from inflammatory features, like furrows, swelling, and white plaques, to structural changes called fibro-stenotic features, such as rings and narrowing of the esophagus. Studies in children have documented this progression clearly: younger patients tend to present with more inflammatory findings, while longer disease duration is associated with increasing fibrosis and stricture formation.12PubMed Central. Eosinophilic Esophagitis in Children: Endoscopic Findings at Diagnosis and Post-intervention
Research correlating endoscopic findings with tissue biopsy results has found that furrows and loss of visible blood vessels in the lining correspond not only to surface inflammation but also to fibrosis in the deeper layers of the esophageal wall.13PubMed Central. Clinical Implications and Pathogenesis of Esophageal Remodeling in Eosinophilic Esophagitis This is important because fibrosis is not easily reversed. The esophagus can become stiffer and narrower, making it harder for food to pass through. Functional studies have confirmed this: EoE patients have measurably reduced esophageal stretch compared to healthy individuals, with the narrowest point in the esophagus expanding to only about 60% of normal capacity under the same pressure.14PubMed Central. Mechanical Properties of the Esophagus in Eosinophilic Esophagitis
The practical implication is that furrows are not just a cosmetic marker. They signal ongoing damage that, if left unchecked, can permanently change the structure and function of the esophagus. Catching and treating the disease while it is still in the inflammatory phase, when furrows and edema dominate the picture, offers the best chance of preventing irreversible stricturing.
How Treatment Reverses Furrowing
Furrows can improve or resolve entirely with effective treatment, which is one of the more encouraging aspects of EoE management. Treatment broadly falls into three categories: medication, dietary elimination, and biologic therapy.
Proton pump inhibitors (PPIs), the same drugs used to treat acid reflux, have an evolving role in EoE that surprises many patients. PPIs were originally used only to rule out acid reflux as a cause of eosinophil buildup. But it became clear that a meaningful subset of EoE patients responded to PPIs, and updated consensus guidelines now recognize PPI therapy as a legitimate treatment for EoE in both children and adults.15PubMed Central. Proton Pump Inhibitor Therapy for Eosinophilic Esophagitis: History, Mechanisms, Efficacy, and Future Directions The mechanism appears to go beyond acid suppression. Research has shown that PPIs can block some of the same inflammatory signaling pathways involved in eotaxin-3 production, acting as a partial anti-inflammatory agent in the esophageal lining itself.5PubMed Central. In Esophageal Squamous Cells From Eosinophilic Esophagitis Patients, Th2 Cytokines Increase Eotaxin-3 Secretion Through Effects on Intracellular Calcium and a Non-Gastric Proton Pump
Dietary elimination therapy works by removing the offending food triggers. When patients systematically cut out the most likely allergens, the results can be dramatic. In a study of adults treated with elimination diets, those who responded saw their total endoscopic score, which includes furrowing, drop from an average of about 3.2 down to 0.7. Eosinophil counts in their tissue plummeted from roughly 50 per high-power field to about 4, and reported dysphagia dropped from 95% of patients to 11%.16PubMed Central. Food Elimination Diets are Effective for Long-term Treatment of Adults with Eosinophilic Oesophagitis These improvements were maintained long-term in patients who stuck with their identified dietary restrictions.
The newest treatment option is biologic therapy. Dupilumab, a drug that blocks the IL-4 receptor and thereby interrupts the Th2 signaling cascade described earlier, was approved for EoE and has shown the ability to reduce eosinophil counts and improve endoscopic findings, including furrowing. By targeting the upstream immune signals rather than individual allergens, biologics offer a systemic approach for patients who do not respond adequately to PPIs or diet, or who find strict dietary elimination unsustainable.
How EoE Looks Different in Children and Adults
The symptoms that lead to an EoE diagnosis differ by age. Adults typically report difficulty swallowing solid foods and episodes of food impaction, which is food getting stuck in the esophagus badly enough to require medical removal. Children, especially younger ones, are more likely to present with feeding difficulties, vomiting, abdominal pain, and failure to thrive. A child who is not old enough to describe swallowing problems may simply refuse to eat certain textures or take abnormally long to finish meals.
Endoscopically, children tend to present with more inflammatory features: edema, furrows, and white plaques are dominant. Over time, if the disease goes untreated, the pattern shifts toward the fibro-stenotic features, rings and narrowing, that are more commonly seen in adults with long-standing disease.12PubMed Central. Eosinophilic Esophagitis in Children: Endoscopic Findings at Diagnosis and Post-intervention This trajectory underscores the idea that furrowing represents an earlier, more treatable phase of EoE. It also means that in pediatric patients, furrows on endoscopy are a strong early warning sign, even before any narrowing has developed.
The “Crepe Paper” Esophagus and Other Visual Patterns
Endoscopists have developed a colorful vocabulary for describing the EoE esophagus. Beyond furrows, there are terms like “feline esophagus” or “felinization” for the concentric rings that make the esophagus look like a ribbed tube, and “crepe paper mucosa” for tissue so fragile that it tears during the procedure itself. White exudates, which look like small white spots or plaques, are clusters of eosinophils visible on the mucosal surface.17ScienceDirect. Endoscopic Characterization of Eosinophilic Esophagitis
These different findings are not just descriptive curiosities. They have been organized into a scoring system called the EREFS (EoE Endoscopic Reference Score), which grades edema, rings, exudates, furrows, and strictures separately. Tracking each component over time helps clinicians distinguish inflammatory activity from structural damage and assess whether treatment is working. A patient whose furrow and exudate scores improve after starting therapy but whose ring score stays the same has likely stopped new inflammation but has not yet reversed existing remodeling. That distinction matters for decisions about whether to add additional therapies or consider dilation of narrowed segments.
The sensitivity and specificity numbers for individual EREFS features are not equal. Exudates have been shown to be the most sensitive single finding for detecting active disease (around 96%), while furrows have among the highest specificity (around 90%), meaning furrows in particular are a strong positive indicator that what you are seeing is indeed EoE and not something else.2PubMed Central. Eosinophilic Esophagitis Reference Score Accurately Identifies Disease Activity and Treatment Effects in Children For the patient, the practical meaning is straightforward: if your endoscopy report mentions longitudinal furrows, EoE should be high on the list of explanations, and a biopsy to confirm the diagnosis is the logical next step.
Esophageal Stiffness and Why It Matters for Everyday Life
Even before strictures are visible on endoscopy, EoE changes how the esophagus functions. The chronic inflammation and early-stage fibrosis reduce the wall’s ability to stretch when food passes through. Researchers have measured this directly using specialized tools that inflate a small balloon inside the esophagus and track how much the wall expands under increasing pressure. In EoE patients, the esophagus stretches to a significantly smaller cross-section than in healthy controls, reaching about 267 square millimeters compared to 438 in control subjects.14PubMed Central. Mechanical Properties of the Esophagus in Eosinophilic Esophagitis
This reduced distensibility explains why many EoE patients feel like food is “sticking” even when there is no visible stricture or narrowing on a standard endoscopy. The esophagus simply cannot expand enough to let larger bites pass comfortably. Many patients unconsciously adapt by chewing food to an extreme degree, eating very slowly, drinking water with every bite, or avoiding certain textures like bread and dry meat. These compensatory behaviors are so common that some patients do not realize anything is abnormal until a food impaction forces an emergency room visit. If you recognize that pattern, it is worth bringing up with your doctor even if you have never had a formal choking event.