A small, firm, painless bump on the inside of the cheek, often right where the teeth meet, is one of the most frequent reasons people ask a dentist to look at a lump. In most cases it turns out to be a fibroma, a knot of tough scar-like tissue that builds up where the lining of the mouth keeps getting rubbed or nipped. It is benign. Still, a few other lumps can look similar, so it is worth knowing what is typical and what deserves a prompt check.
Fibromas are the usual explanation
A fibroma is the most common answer when a solid lump is found in the mouth. In a 2019 retrospective review of benign oral lumps and tumour-like lesions (Błochowiak and colleagues, Advances in Dermatology and Allergology), fibroma was the most frequent diagnosis, ahead of mucoceles and papillomas.
The cause is mechanical. When one spot is irritated over and over, perhaps by a chipped tooth, a rough filling edge, a denture flange or a habit of chewing the cheek, the tissue responds by laying down extra collagen. That repair tissue gradually forms a nodule. This is why fibromas tend to sit along the bite line of the inner cheek, on the lower lip or on the side of the tongue: they appear exactly where the friction happens.
What a typical fibroma feels like
Most fibromas are a few millimetres across, smooth and dome-shaped, and firm when pressed, a bit like a small pea under the lining. They are usually the same pink as the surrounding tissue, or a little paler where the surface has thickened. They do not hurt unless you bite them, and they tend to stay much the same size for months or years.
Those features are reassuring, but they are not a diagnosis on their own. Some less common lumps share the same appearance, which is why a dentist will want to examine a lump rather than rely on a description.
Signs that a lump needs a prompt look
Book an examination sooner rather than later if a lump:
- feels hard, fixed in place or irregular, rather than smooth and slightly movable
- is growing over a matter of weeks
- bleeds, has an ulcer on its surface, or is painful or numb
- sits within or next to a red, white or speckled patch
- is new and has not settled or has changed within three weeks.
Three weeks gives ordinary bites and scrapes time to heal, so anything still there after that should be seen by a dentist or GP. Most persistent lumps are still harmless, but this is the same threshold we use in our guide to oral cancer screening.
Other lumps that can look similar
Not every bump is a fibroma. A soft, bluish, fluid-filled swelling on the lower lip is often a mucocele, caused by a blocked or damaged minor salivary gland. A similar, larger swelling in the floor of the mouth may be a ranula. Swellings on the gum next to a tooth can come from infection or from tissue overgrowth around plaque or a rough edge. Small cauliflower-like growths are often papillomas. Flat white or red areas, rather than raised lumps, belong to a separate group discussed in our article on white and red patches.
A dentist sorts these out by looking at where the lump is, how it feels, what colour it is and how long it has been there, together with any obvious source of irritation nearby.
Leaving it, or removing it
A small fibroma that has been examined, is not changing and does not get in the way can often be left alone and checked at routine visits. Clinical photographs can help compare it accurately from one visit to the next.
If the lump keeps being bitten, interferes with eating, or you would simply prefer it gone, it can be removed in a short procedure under local anaesthetic. The tissue is usually sent to a pathology laboratory to confirm what it is, which is standard practice for any lump that is taken out. Most people find the area tender for a few days while it heals.
Removal deals with the lump. Treating the cause is just as important: smoothing a sharp tooth, polishing or replacing a rough filling, adjusting a denture, or working on a cheek-chewing habit. If the irritation continues, a new fibroma can form in the same place. Our companion article on traumatic fibromas and cheek biting looks more closely at those causes and how to prevent a return.
What people often ask
Can a fibroma turn into cancer?
A fibroma is a benign reaction to irritation. The reason to have a lump examined is to make sure it really is a fibroma, because a small number of lumps that look similar are something else.
Will it shrink on its own?
Usually not. Removing the source of rubbing may stop it growing, but the tissue that has already formed tends to stay unless it is removed.
Is removal painful?
The area is numbed first, so the procedure itself should not hurt. Expect some tenderness for a few days afterwards.
If you have found a lump in your mouth, our dentists can examine it, explain what it is likely to be and talk through whether to monitor or remove it. Book with our general dentistry team in Melrose Park, or see current offers for new patients.
