Sentinel pile: what is the lump next to a chronic anal fissure?

What is a sentinel pile?

Many people with a long-standing fissure notice a small lump at the edge of the anus and conclude that they "also have a hemorrhoid". In most of these cases, what they feel is a sentinel pile, also called a sentinel tag or sentinel skin tag. It is a fold of skin, usually 3 to 10 millimeters long, sitting exactly at the outer end of the fissure, like a guard posted at the entrance of the tear. That is where the name comes from.

It is made of skin and scar tissue, not of blood vessels. Every time a stool stretches the fissure, the outer edge of the tear swells. Over weeks, that swelling organizes into fibrous tissue and the skin over it stays raised, even when the inflammation calms down. The result is a soft-to-firm, skin-colored tag that does not change size when you strain.

Colorectal surgeons read the sentinel pile as part of a picture. A chronic fissure usually shows several of these signs at once:

• Thick, pale edges instead of the fresh, pink edges of a new tear.
• White fibers of the internal sphincter visible at the base of the fissure.
• A hypertrophied anal papilla, a small fleshy bump at the inner end of the tear, inside the canal.
• The sentinel pile at the outer end, the only one of the signs you can usually see or feel yourself.

If you want the full picture of how a fissure changes over time, read Acute or chronic anal fissure? What changes after 6 to 8 weeks and our page on chronic anal fissure.

Why does a sentinel pile form?

The sentinel pile is a consequence of the fissure, not its cause. To understand it, you need the mechanism that keeps a fissure open, which we explain step by step in What is an anal fissure? A surgeon explains it with a drawing of the anal canal.

1. The tear. A hard or bulky stool, or repeated diarrhea, tears the anoderm, the thin skin lining the lower anal canal. Most fissures sit in the back midline; in women, a minority sit in the front.
2. The spasm. The pain makes the internal anal sphincter contract. A tight sphincter squeezes the small vessels that feed the area, and the tear does not get enough blood to heal.
3. The repeated injury. Each bowel movement reopens the tear. The skin at its outer edge, the part exposed outside the anal opening, swells again and again.
4. The scar. After several weeks, the chronic swelling (lymphedema) and the repair tissue harden into a permanent fold. That fold is the sentinel pile.

That is why a sentinel pile is a marker of time. A fissure that is a few days old almost never has one; a fissure that has been opening and closing for two or three months often does. The tag tells your surgeon two useful things: the fissure is probably chronic, and the treatment plan should be a full course of a sphincter-relaxing ointment rather than a few days of a soothing cream.

How can you tell a sentinel pile from an external hemorrhoid?

This is the most common confusion we see in clinic, and it matters, because the treatments are different. Hemorrhoid creams and hemorrhoid procedures do nothing for a sentinel pile, and the fissure behind it stays open. Here is how the two compare:

A practical rule from the clinic: if the lump sits in the midline and the main symptom is sharp pain with bowel movements that lingers afterwards, think fissure with a sentinel pile. If the lump appeared overnight, is purple and hurts constantly whether or not you go to the toilet, think thrombosed external hemorrhoid. Also remember that residual skin tags left by an old hemorrhoid look very similar to a sentinel pile; the difference is the fissure next to it. We go deeper into the differences in Fissure or hemorrhoids? The pain rule that tells them apart.

Does a sentinel pile go away when the fissure heals?

Partly. Once the fissure closes and the area stops being injured with every bowel movement, the swelling inside the tag subsides. Many sentinel piles shrink noticeably over the following weeks or months. Some flatten so much that the patient no longer feels them. Others remain as a small, painless fold of skin, because the scar tissue does not disappear.

What matters is that a remaining tag is not a sign that the fissure is still open. The fissure is judged by symptoms (pain and bleeding with bowel movements) and by examination, not by whether the tag is there. If the pain has gone and the tag stays, the treatment worked.

The opposite also holds: shrinking the tag is not a treatment goal. Creams for hemorrhoids, steroid ointments or "natural" ointments applied to make the lump smaller miss the point. Steroids in particular thin the skin and slow healing, so never use hydrocortisone for more than 7 days. The goal is to close the fissure, and that requires soft stools and relaxing the internal sphincter for 6 to 8 weeks.

Should a sentinel pile be removed?

Our general answer is: not on its own, and not while the fissure is open. Removing the tag leaves a wound right at the edge of an area that already heals poorly because of the sphincter spasm. Cutting it off does not lower the pressure of the sphincter, so the fissure stays open and you have a second wound to heal.

The usual scenarios are these:

• Fissure still open, being treated with ointment: leave the tag alone. Focus on stools and a full 6- to 8-week course of nifedipine or diltiazem (nitroglycerin as an alternative).
• Chronic fissure that needs surgery: when the fissure does not heal with medical treatment, the next steps are botulinum toxin or a lateral internal sphincterotomy. If surgery is done, the surgeon generally removes the sentinel pile, and often the hypertrophied papilla, in the same procedure, so the scar heals as a single wound. The Cochrane review of operative procedures (27 trials, 2,056 patients) confirmed that open and closed sphincterotomy are equally effective. Read more in All guides.
• Fissure healed, tag remains: if the tag is small and painless, nothing needs to be done. If it is large and makes hygiene difficult or keeps the skin irritated, removal can be discussed with a colorectal surgeon once the fissure has been closed for a while, and only after an examination confirms that no fissure persists.

Never try to tie, cut or "burn off" a tag at home, and do not let anyone treat it as a hemorrhoid with banding: banding is for internal hemorrhoids, above the pain-sensitive zone, and the tag sits in the most sensitive skin of the body.

When should a skin tag near the anus worry you?

A typical sentinel pile is small, skin-colored, in the midline and next to a fissure that hurts with bowel movements. If what you see or feel does not fit that picture, it needs an examination, not a cream. See a doctor without delay if you notice:

Crohn’s disease deserves a specific mention, because its skin tags can look like sentinel piles. A 2025 review estimated that around 45 % of people with Crohn’s disease develop non-fistulizing perianal lesions such as fissures, ulcers, strictures and skin tags. In Crohn’s, tags tend to be larger, swollen and bluish, and fissures tend to be off the midline or multiple. If you have diarrhea, abdominal pain or weight loss together with these findings, see Anal fissure and inflammatory bowel disease: how is a Crohn’s fissure different?.

Where does FISURIN fit?

FISURIN does not remove a sentinel pile, and no cream does. What it targets is the fissure behind the tag: it combines nifedipine, a sphincter relaxant, with lidocaine for pain, in a water-based hydrogel used with a written 6-week protocol, prescribed by our surgeons at Clínica Proctológica de Lima for chronic and post-operative fissures. A randomized double-blind trial of nifedipine 0.3 % with lidocaine 1.5 % reported healing in 94.5 % of chronic fissures at 6 weeks, against 16.4 % in the control group (Perrotti, 2002); that is a study result, not a promise for every patient. Today FISURIN is a magistral formula prepared under prescription in Peru and is not shipped abroad; FISURIN Hydrogel and FISURIN Relief are in preparation, with a waiting list. See what is inside FISURIN or how to get it where you live.