Fibroepithelial polyps are among the most common benign growths in the human body, most familiar as the soft, flesh-colored nubs known as skin tags. They are small, pedunculated (stalk-attached) outgrowths of skin or mucosa that appear overwhelmingly in areas where skin folds or rubs against itself. Despite being harmless in the vast majority of cases, fibroepithelial polyps have drawn significant clinical attention because of their surprisingly strong links to metabolic disease, their tendency to appear in internal organs where they can mimic cancer, and the fact that they occasionally grow to dramatic sizes that defy their reputation as trivial nuisances.
Where Fibroepithelial Polyps Grow
The classic locations are the neck, armpits, groin, and eyelids. These are all areas subject to skin-on-skin or skin-on-clothing friction, and the pattern is consistent enough that friction is widely considered a contributing cause. One case report described a patient with multiple skin tags arranged in a straight line, strongly suggesting that repeated rubbing against a surface triggered their formation.1PubMed. Friction induced skin tags Beyond those familiar spots, fibroepithelial polyps also grow on the chest wall, under the breasts, and in the genital area.2PubMed Central. Giant Fibroepithelial Polyps: Why do they Grow Excessively?
What surprises most people is that fibroepithelial polyps are not limited to the skin. They also develop inside the body, particularly in the urinary tract and the lower female genital tract. Ureteral fibroepithelial polyps grow on the lining of the ureter, the tube connecting the kidney to the bladder, and present very differently from a skin tag. Vaginal and vulvar fibroepithelial polyps form on mucosal surfaces and can become quite large, especially during pregnancy. These internal variants share the same basic structure as a skin tag but raise entirely different clinical questions, which is why the term “fibroepithelial polyp” appears across dermatology, urology, and gynecology literature.
Why They Form
No single cause explains all fibroepithelial polyps, but several mechanisms converge. Friction is the most intuitive. Repeated mechanical irritation of the skin appears to trigger a local tissue response in which mast cells, a type of immune cell, accumulate in the area and drive connective-tissue growth. Research has found that mast cell density in skin tags is significantly higher than in normal surrounding skin, and the level of an inflammatory signaling molecule called TNF-alpha is markedly elevated as well.3PubMed Central. The Possible Role of Trauma in Skin Tags Through the Release of Mast Cell Mediators A separate study confirmed the mast cell finding and added that high mast cell tryptase expression was associated with increased collagen deposition and the presence of eosinophils, suggesting mast cells help recruit other immune cells that together promote the fibrous overgrowth characteristic of a skin tag.4PubMed. Role of mast cells in skin tag development: an immunohistochemical study
Human papillomavirus may also play a role, though this remains debated. One study found HPV DNA (specifically types 6 and 11) in about half of the skin tags tested,5PubMed. Human papillomavirus and skin tags: Is there any association? while an earlier study detected HPV 6/11 in roughly nine out of ten specimens examined.6PubMed. The detection of human papillomavirus DNA in skin tags The wide gap between those detection rates hints at differences in methodology and sample selection. Researchers have not established that HPV causes skin tags in the way it causes warts, but the virus does seem to be present far more often than you would expect by chance, which suggests it may act as a co-factor alongside friction and metabolic drivers.
The Metabolic Connection
If you have multiple skin tags, your doctor may see it as a soft signal worth investigating. A growing body of evidence links fibroepithelial polyps of the skin to insulin resistance, obesity, and metabolic syndrome, the cluster of conditions that raises cardiovascular risk. In one study, insulin resistance (measured by the HOMA-IR index) was directly associated with skin tags regardless of whether a person had diagnosed diabetes, and people with markedly elevated HOMA-IR scores had roughly seven and a half times the odds of having skin tags compared to those with normal values.7PubMed. Association between skin tags and insulin resistance
The metabolic picture extends beyond blood sugar. One study found that patients with skin tags had significantly higher levels of glucose, insulin, inflammatory markers (high-sensitivity C-reactive protein), uric acid, free fatty acids, total cholesterol, LDL cholesterol, and triglycerides compared to controls. Over half of the skin tag patients were overweight, about a third were obese, and roughly 30 percent had hypertension.8PubMed. The metabolic profile in patients with skin tags A case-control study from eastern India echoed these findings, reporting that the risk of metabolic syndrome was about eleven times higher in people with skin tags than in matched controls.9PubMed Central. Association of Skin Tag with Metabolic Syndrome and its Components: A Case–control Study from Eastern India
Interestingly, the relationship between skin tags and diabetes specifically is not as straightforward as it sometimes gets portrayed. A clinical evaluation found that while skin tags were slightly more common in diabetic patients than in non-diabetic ones, the difference was not statistically significant.10PubMed Central. A Clinical Evaluation of Skin Tags in Relation to Obesity, Type 2 Diabetes Mellitus, Age, and Sex The stronger, more consistent association appears to be with insulin resistance itself and with the broader metabolic syndrome profile rather than with diabetes as a standalone diagnosis. The mechanism likely involves insulin-like growth factor, which circulates at higher levels in insulin-resistant states and stimulates the growth of skin cells and connective tissue.
Research has also examined a potential link between skin tags and cardiovascular risk more directly. One study compared patients with skin tags who had cardiac disease to those with skin tags but no cardiac history and to healthy controls. The rates of metabolic syndrome were dramatically different across the groups, and both skin-tag groups showed significantly higher triglyceride and cholesterol levels than controls.11PubMed Central. The Evaluation of the Impact of Age, Skin Tags, Metabolic Syndrome, Body Mass Index, and Smoking on Homocysteine, Endothelin-1, High-sensitive C-reactive Protein, and on the Heart None of this means skin tags cause heart disease, but in aggregate the data support the idea that skin tags serve as a visible, low-cost clue that the metabolic machinery underneath may be off-track.
Hormones and Growth Spurts
Fibroepithelial polyps are hormone-responsive, and nowhere is this more obvious than during pregnancy. Existing skin tags can enlarge, and new ones can appear as estrogen and progesterone levels surge. In the lower female genital tract, this hormonal sensitivity can occasionally produce dramatic results. A case report described a giant vulvar acrochordon that appeared during the second trimester of pregnancy, consistent with the observation that these lesions are hormone-responsive and common on mucosal and cutaneous surfaces of women of reproductive age.12BMJ Case Reports. Giant vulvar acrochordon (skin tag) presenting in second trimester of pregnancy
Microscopic examination of vaginal fibroepithelial polyps reveals stromal cells that reliably express receptors for estrogen and progesterone, confirming that these growths are biologically wired to respond to sex hormones.13PubMed Central. An Unusual Presentation of Giant Fibroepithelial Polyp of the Vagina This explains why they can swell quickly during pregnancy and may shrink afterward. Another hormonal context in which skin tags appear is acromegaly, a condition marked by excess growth hormone and its downstream messenger IGF-1. Pigmented skin tags are a recognized skin manifestation of acromegaly.14PubMed. Skin manifestations in acromegaly This ties back to the insulin resistance connection, since both acromegaly and metabolic syndrome involve elevated IGF-1 signaling that promotes tissue overgrowth.
When a Skin Tag Is Not a Skin Tag
Most fibroepithelial polyps never need to be biopsied. But occasionally, a growth that looks and feels exactly like a skin tag turns out to be something else entirely. In one published case, a lesion removed as a presumed skin tag was found on pathology to be a cutaneous leiomyosarcoma, a rare smooth-muscle cancer. The authors noted that malignant tumors resembling skin tags, while uncommon, are most frequently basal cell carcinomas, and recommended that solitary, wide-based, papilloma-like lesions should be submitted for histologic examination to rule out malignancy.15Journal of Cutaneous Pathology. Cutaneous Leiomyosarcoma Resembling a Skin Tag
Misdiagnosis also runs in the opposite direction, especially for genital fibroepithelial polyps. Large vulvar fibroepithelial polyps can be mistaken for vulvar cancer because of their size and alarming appearance, even though they are benign. Surgical excision is the standard treatment, recurrence is uncommon, and outcomes are excellent once the correct diagnosis is made.16PubMed Central. Unveiling the Truth: Fibroepithelial Polyp of the Vulva and Its Misdiagnosis as Cancer During pregnancy, the diagnostic confusion can be even more pronounced because fibroepithelial stromal polyps of the vagina sometimes develop hypercellularity and bizarre-looking cells that pathologists can mistake for sarcoma, despite the lesion’s completely benign behavior.17PubMed Central. Cellular pseudosarcomatous fibroepithelial stromal polyp of the vagina during pregnancy: a lesion that is overdiagnosed as a malignant tumor This “pseudosarcomatous” variant has also been reported in the renal pelvis, where the atypical stromal cells and mitotic figures can similarly suggest a malignant process that is not actually present.18PubMed. Cellular pseudosarcomatous fibroepithelial stromal polyp of the renal pelvis
Fibroepithelial Polyps Inside the Urinary Tract
Ureteral fibroepithelial polyps are a distinct clinical entity that shares a name and basic tissue architecture with skin tags but otherwise has little in common with them. These polyps grow from the lining of the ureter and typically cause flank pain or blood in the urine. They are uncommon, and diagnosing them is genuinely difficult because standard imaging like CT scans and MRIs often fails to detect them. Retrograde pyelography, a procedure in which dye is injected upward into the ureter and X-rays are taken, will typically show a smooth filling defect, and the definitive diagnosis usually comes from passing a scope into the ureter and seeing the polyp directly.19PubMed Central. Ureteral fibroepithelial polyp: A diagnostic challenge
A systematic review of the literature found descriptions of 134 patients with ureteral fibroepithelial polyps. Most had a single polyp, though some had as many as ten. The median polyp length was 4 centimeters, but sizes ranged from under half a centimeter to 17 centimeters.20PubMed Central. Treatment and outcome of fibroepithelial ureteral polyps: A systematic literature review Treatment has evolved from open surgery toward minimally invasive options including endoscopic, laparoscopic, and robotic approaches.21PubMed. Minimally Invasive Surgical Therapies for Ureteral Polyps: A Systematic Review One retrospective study comparing two types of laser resection during ureteroscopy found both effective, with thulium laser showing an advantage in reducing the risk of post-surgical narrowing of the ureter.22PubMed. Treatment of Ureteral Fibroepithelial Polyp by Ureteroscopy Combined with Holmium Laser or Thulium Laser: A Retrospective Study
In children, fibroepithelial polyps can arise in the bladder neck or prostatic urethra and are considered congenital. They tend to present with urinary symptoms like difficulty voiding or blood in the urine and are treated with transurethral resection. Two reported pediatric cases, in boys aged two and five, were symptom-free one and five years after surgery, respectively, though the authors noted that long-term follow-up is warranted because recurrence is possible.23PubMed. Fibroepithelial polyp of the bladder neck in children
Removing Skin Tags
For the garden-variety skin tag on the neck or armpit, treatment is elective. Most skin tags do not grow, do not become cancerous, and do not cause symptoms beyond occasional cosmetic self-consciousness or mild irritation when they catch on clothing or jewelry. When removal is desired, several methods are available: snip excision with scissors, electrosurgery (using a small electrical current to burn the base), and cryotherapy (freezing with liquid nitrogen). A randomized clinical trial comparing electrosurgery and cryotherapy for several benign skin lesions including skin tags found that patient and physician satisfaction was significantly higher with electrosurgery than with cryotherapy.24PubMed Central. Evaluation and Comparison of the Efficacy and Safety of Cryotherapy and Electrosurgery in the Treatment of Sebaceous Hyperplasia, Seborrheic Keratosis, Cherry Angioma, and Skin Tag: A Blinded Randomized Clinical Trial Snip excision remains the simplest and fastest approach for small, pedunculated tags, and many dermatologists prefer it for that reason.
Over-the-counter skin tag removal kits, typically based on freezing or ligation (tying off the base to cut blood supply), are widely sold. They work on small tags but carry a higher risk of incomplete removal, scarring, or infection compared to a quick in-office procedure. Home remedies involving tea tree oil, apple cider vinegar, or string are popular but have no rigorous clinical evidence supporting their effectiveness. The practical advice is straightforward: if a skin tag is small and bothers you, an office visit for removal is fast, inexpensive, and definitive. If the growth is large, unusually firm, rapidly growing, or irregularly colored, get it looked at rather than removing it yourself, because those features raise the probability that it is not a simple skin tag.
Fibroepithelial Polyps in Animals
The same basic lesion shows up in veterinary medicine, which is useful because it helps confirm theories about causation. A study of 21 dogs with oral fibroepithelial polyps (sometimes called “chewing granulomas”) found that the polyps typically arose under or beside the tongue and had thick fibrovascular stalks with dense collagen, hyperplastic surface epithelium, and frequent ulceration and inflammation. None recurred after surgical removal. The chronic irritation pattern was striking enough that the authors concluded chronic oral trauma was likely the primary driver.25PubMed. Oral fibroepithelial polyps (“chewing granulomas”) in 21 dogs: Histomorphology, immunohistochemical characterization, and clinical outcome
In female dogs, vaginal fibroepithelial polyps also occur and share histological features with their human counterparts, including stromal cells that express vimentin and desmin. Some canine cases showed changes suggestive of papillomavirus infection, paralleling the HPV findings in human skin tags.26PubMed. Fibroepithelial polyps of the vagina in bitches: a histological and immunohistochemical study The cross-species consistency reinforces the idea that fibroepithelial polyps are a conserved tissue response to chronic irritation and hormonal stimulation rather than a uniquely human quirk. Dogs do not develop insulin resistance in the same patterns humans do, yet they still produce these polyps in mechanically stressed tissue, which underscores how central the friction-and-inflammation pathway is to their formation.