What Does an Indentation in the Breast Mean?

An indentation in the breast can result from a wide range of causes, some completely harmless and others worth prompt medical attention. The concern most people have when they notice a new dent or dimple is breast cancer, and that concern is not unfounded: skin dimpling is a recognized sign that a tumor may be pulling on the internal support structures of the breast. But cancer is only one item on a longer list that includes prior trauma, a benign vascular condition called Mondor’s disease, post-surgical scarring, chest wall anatomy, and inflammatory conditions that can mimic malignancy on imaging.

Why Breast Cancer Can Cause a Visible Dent

The breast contains a network of fibrous bands called Cooper’s ligaments that run from the chest wall through the breast tissue to the skin. These ligaments act like an internal scaffold, helping maintain the breast’s shape. When a tumor grows into or near these ligaments, it can shorten and tighten them, pulling the overlying skin inward and creating a visible dimple or indentation. Researchers have described this as a sign of “early skin tethering,” noting that a tumor’s involvement of Cooper’s ligaments can produce subtle skin changes long before the tethering becomes obvious to the naked eye.¹

A large study examining how breast cancer presents clinically found that dimpling was present in 264 cancer cases and was often associated with smaller, earlier-stage tumors described as “minimal” lesions.² That detail matters: skin dimpling does not necessarily mean a cancer is advanced. In some patients, the dimple only became apparent when the examiner physically manipulated the area around the tumor, meaning a subtle indentation that shows up in certain positions or with certain movements is still worth investigating.

Inflammatory breast cancer, a less common but aggressive form, can also alter the skin’s surface. Rather than producing a single focal dimple, it tends to cause widespread skin thickening, redness, and a peau d’orange (orange-peel) texture across much of the breast. A multi-center study found that about 91% of inflammatory breast cancer cases exhibited erythema (redness), and roughly 57% showed mammographic evidence of skin thickening, compared to far lower rates in non-inflammatory cancers.³ If an indentation is accompanied by redness, warmth, or the skin looks swollen and textured across a broader area, that pattern raises more concern for inflammatory disease and warrants urgent evaluation.

Mondor’s Disease and the Linear Indentation

Not every indentation is round. Some people notice a long, narrow groove running along the surface of the breast, almost like a line pressed into the skin. This pattern is characteristic of Mondor’s disease, a condition in which a superficial vein in the breast wall becomes inflamed and clots off. The clotted vein hardens into a cord-like structure beneath the skin, and the surrounding inflammation pulls the overlying skin downward, creating a linear indentation.

In one reported case, a patient presented with a palpable cord-like fibrous lesion and a linear retraction of the breast skin extending from the upper outer area toward the nipple.⁴ The indentation can sometimes be noticeable only when standing upright, because gravity pulls the breast tissue downward and exposes the tethered skin. A review of Mondor’s disease cases noted that most patients were diagnosed based on history and physical examination alone, with typical features including localized pain, tenderness, a palpable cord, and retraction or indentation of the skin.⁵

Mondor’s disease is benign. It usually resolves on its own within weeks to a couple of months, often with nothing more than anti-inflammatory medication and warm compresses. But because a linear indentation can look alarming, imaging is sometimes performed to rule out an underlying mass. If you notice what looks like a groove or furrow rather than a round dimple, and it is tender to the touch with a firm cord underneath, Mondor’s disease is high on the list of explanations.

Fat Necrosis After Trauma or Surgery

The breast contains a substantial amount of fatty tissue, and when that tissue is injured, it can die off and be replaced by scar tissue or calcified lumps. This process is called fat necrosis. It happens after direct trauma to the breast, like a seatbelt injury in a car accident, a sports collision, or even a fall. A case series examining women who sustained breast injuries found that the majority of resulting imaging abnormalities were attributable to fat necrosis.⁶

Fat necrosis can form a firm lump that pulls on surrounding tissue, creating a dimple in the skin that looks and feels suspicious. On a mammogram, fat necrosis can mimic cancer with its irregular borders and calcifications, which is why it sometimes triggers biopsies even though it is entirely benign. The key clue is usually the patient’s history: if you recall a specific injury to the breast, or you have had a prior biopsy or surgery in that area, fat necrosis becomes a likely explanation for any new indentation. People sometimes forget the initial injury, though, and the scar tissue can take months to mature to the point where it causes a visible skin change, making the connection easy to miss.

Post-Surgical and Radiation Changes

Breast surgery and radiation therapy are common causes of indentations that people sometimes mistake for new problems. After a lumpectomy (removal of a tumor with a margin of surrounding tissue), the area where tissue was removed can contract as it heals, pulling the skin inward. If radiation therapy follows the surgery, the effect can be amplified because radiation causes gradual fibrosis, a stiffening and shrinking of irradiated tissue over months to years.

Evaluation of cosmetic outcomes after lumpectomy and radiation has identified a characteristic pattern of deformity that can include displacement of the nipple, loss of skin elasticity, and loss of underlying breast volume.⁷ These changes can produce anything from a barely noticeable contour irregularity to a deep indentation at the surgical site. The indentation is typically stable once it develops, though radiation fibrosis can worsen slowly over time.

Fat grafting, where fat harvested from another body area is injected into the breast, has become a common technique for correcting these contour deformities. It can be used as a standalone approach or alongside other reconstructive methods to restore a more natural breast shape.⁸ If you have an indentation at the site of a prior procedure and it bothers you, this is a conversation worth having with a plastic or reconstructive surgeon.

Granulomatous Conditions That Mimic Cancer

Certain inflammatory and infectious conditions can cause breast indentations that look worryingly similar to cancer on both physical examination and imaging. Granulomatous diseases of the breast, which include conditions like granulomatous mastitis and tuberculosis of the breast, can produce irregular masses, skin retraction, and even nipple retraction. A radiological review noted that these conditions have a variable appearance on imaging and can mimic malignancy, with fistulas to the skin and nipple retraction sometimes suggesting a chronic granulomatous process rather than cancer.⁹

These conditions are uncommon in Western countries but are seen more frequently in parts of the developing world and in immigrants from those regions. Granulomatous mastitis in particular tends to affect younger women, often within a few years of pregnancy. It can produce breast pain, swelling, skin changes including indentation, and sometimes draining sinuses through the skin. Because the imaging findings overlap heavily with cancer, a tissue biopsy is almost always needed to make the correct diagnosis. Treatment is usually medical rather than surgical, involving anti-inflammatory or immunosuppressive medications, which makes getting the diagnosis right all the more important.

When the Chest Wall Itself Is the Cause

Sometimes the indentation is not in the breast tissue at all but in the chest wall beneath it. Pectus excavatum, a condition where the breastbone is sunken inward, can distort the way the breast sits on the chest. In women, this can cause the breasts to appear asymmetric, slant inward, or seem to have a depression in one area where the underlying rib cage is concave.

Research comparing women with pectus excavatum to those without has found that breast volume in affected women was significantly smaller on both sides, with no significant difference between right and left breasts. However, the chest wall depression can make one breast appear noticeably different from the other, particularly when it is asymmetric.¹⁰ In one case report, a woman with severe asymmetric pectus excavatum still had visible breast asymmetry and a depressed anterior chest wall even after undergoing correction of the chest wall itself.¹¹

A related study found that the breasts in women with pectus excavatum tend to slant medially, following the angle of distorted ribs, and that surgical correction of the chest wall increased the distance between nipples, indicating the inward breast positioning had been partly corrected.¹² If you have always had an indentation or asymmetry in the breast area and it has not changed over time, a chest wall issue like pectus excavatum may be the explanation rather than anything happening in the breast tissue itself. This is something your doctor can usually identify on a standard physical exam.

Congenital Differences in Breast Development

Some indentations or shape irregularities are present from the time the breast develops during puberty. Poland syndrome, a congenital condition involving underdevelopment or absence of the pectoralis muscle on one side of the chest, frequently causes the breast on that side to be noticeably smaller, differently shaped, or positioned differently than the other. The condition can range from mild, where the breast is simply a bit smaller, to severe, where the chest wall is visibly concave and the breast is nearly absent.¹³

Because Poland syndrome affects both the chest wall and the muscle beneath the breast, it can create the appearance of a deep indentation in the breast area. The clinical presentation varies widely from person to person. Reconstructive options depend on the severity and can include anything from breast augmentation with implants to autologous tissue transfer, where tissue from elsewhere in the body is moved to the chest. If you have had a noticeable difference in your breasts since adolescence, particularly if one side of your chest also seems less muscular or slightly sunken, Poland syndrome is one possible explanation worth discussing with a doctor.

How Doctors Evaluate a New Breast Indentation

If you notice a new indentation, the evaluation typically starts with a clinical breast exam. Your doctor will look at the breast in different positions, often asking you to raise your arms, lean forward, or press your hands on your hips to contract the pectoral muscles. These maneuvers can make subtle dimpling more visible. As the research on cancer presentation noted, dimpling sometimes only appears with manipulation of the area, so a thorough physical exam includes these positional checks.²

Imaging typically comes next. A mammogram and breast ultrasound are the standard first-line tools. The mammogram provides a broad view and can detect masses, calcifications, and architectural distortion, which is a pattern where the normal tissue lines of the breast appear pulled toward a central point. Architectural distortion can be caused by cancer, but it can also result from benign entities like radial scars, which are star-shaped areas of fibrosis. A pathology review of radial scars describes them as benign lesions with a central fibrotic core and radiating ducts, commonly present in the population, especially alongside other benign breast disease.¹⁴ The practical point is that if imaging shows architectural distortion under your indentation, it does not automatically mean cancer, but it does usually mean a biopsy is recommended to sort out what is there.

MRI is sometimes added when mammography and ultrasound are inconclusive, or in women at high risk for breast cancer. If a mass or suspicious area is found, a core needle biopsy provides a tissue sample that can be examined under a microscope to determine the diagnosis. The whole process, from noticing the indentation to getting a definitive answer, can take a few weeks depending on scheduling, but the important step is starting it. A new indentation deserves evaluation even if you are fairly sure the cause is benign, because the clinical appearance of benign and malignant causes can overlap too much to tell apart without imaging.

Indentations That Have Always Been There Versus New Ones

The single most useful piece of information, both for you and for your doctor, is whether the indentation is new. A dimple or contour irregularity that has been present since your breasts developed, or that appeared after a known event like surgery or trauma, is far less concerning than one that showed up recently with no obvious explanation.

Long-standing indentations are most often related to chest wall anatomy, congenital differences, old scar tissue, or normal variation in breast shape. Many people have mild asymmetry or slight contour differences between their breasts that are simply the way their tissue is distributed. These do not require investigation unless they change.

A new indentation, especially one that appeared over the span of weeks to months, warrants a call to your doctor even if it is not painful. Pain is actually not a reliable discriminator here: most breast cancers are painless, while Mondor’s disease and fat necrosis are often tender. The presence or absence of a palpable lump underneath the indentation is also not definitive on its own, since both benign and malignant causes can present with or without a discrete mass. What matters is the change. If you see something new, get it checked. The evaluation is straightforward, the imaging is well-established, and the majority of breast indentations turn out to have a benign explanation.

Practical Steps if You Notice an Indentation

Stand in front of a mirror with good lighting and look at your breasts in three positions: arms at your sides, arms raised overhead, and hands pressed firmly against your hips. Compare both sides. A true indentation will often become more or less visible depending on the position, which is useful information for your doctor. Note whether the dimple is round and focal, or whether it follows a linear pattern. Feel the area gently: is there a lump, a cord, tenderness? Write these observations down before your appointment.

If you have had prior breast surgery, radiation, or a known trauma to the area, mention that upfront. It can significantly change how aggressively the finding needs to be pursued. Bring any prior mammogram or imaging reports if you have them, since comparison with previous images is one of the most powerful tools radiologists have for determining whether a finding is new or long-standing.

Avoid searching online for images to compare, as the visual overlap between benign and malignant skin changes is too great for self-diagnosis, and alarming images tend to dominate search results. The goal is not to diagnose yourself but to get the right evaluation started without delay. Most indentations are not cancer. But the ones that are tend to benefit enormously from early detection, which is why the threshold for seeking an exam should be low.