A hematoma is a collection of blood, usually the result of bleeding somewhere inside the breast tissue. Hematomas can be caused by a number of things, such as trauma from a sports injury or car accident, or a hard bump to a weak blood vessel. But in the context of breast cancer, hematomas are a common development following breast cancer surgical treatments. Small amounts of bleeding are common after core needle breast biopsies.
Hematomas tend to be visible and palpable and usually develop just below the skin, which might itself appear broken and bruised. Most hematomas are in fact very small, perhaps the size of a grain of rice. A 'large' breast hematoma might grow to the size of an apricot. What often happens though, is that a woman who has undergone some degree of surgical intervention for breast cancer takes a follow-up mammogram, and the curious 'mass-like' appearance of a hematoma on the X-ray has to be evaluated, just to make sure it is not a 'local recurrence' of the breast cancer.
Hematomas are usually quite obvious and predictable on mammogram and particularily on corresponding ultrasound, so they do not usually require biopsy. Very small hematomas may not even be detected on a mammogram, but when they are large enough to be seen, they typically appear as a well-defined oval mass. Less frequently, a hematoma may appear on the x-ray as a nodular image (a nodule usually refers to something with solid elements) with well-circumscribed margins, possibly with an edema (a build up of fluid, - basically water) around the periphery. Hematomas frequently occur in combination with a breast seroma (accumulation of clear 'blood-serum') and that can cause a little bit of ambiguity on the mammogram, but usually this is fully diagnosed with a subsequent ultrasound.
As hematomas tend to resolve on their own, the mass will likely not show up on a follow-up mammogram. However, as they dissipate, fibrous tissue (scar tissue) can grow in the area of the former hematoma and this can give an appearance of a 'proliferative' growth (which could possibly indicate breast cancer cell growth). This is not unexpected, but will still require the screening doctors to take a closer look. Usually this residual fibrous-scar tissue will appear as an architectural distortion on the mammogram; an oddly rearranged segment of breast tissue with a 'spikey' outline. These sorts of 'focal asymmetries' are very common and occur in about 60% of all breast hematomas, and an ultrasound will usually be sufficient to make the situation clear. But sometimes even the ultrasound can be inconclusive; the transitional nature of hematomas can present as a strange combination of liquid and solid elements. If there is any uncertainly, (perhaps a finding of irregular margins and a non-homogeneous hypochoic nodule) a biopsy will undertaken.
Calcifications may develop in later stages of the dispersal of a hematoma, but these are quite easily distinguished from the common microcalcification patterns associated with ductal carinoma, and are to be expected.
Hematomas usually resolve on their own, but that can take quite a while (4-6 six weeks, sometimes longer). Very large hematomas might have to be surgically drained. That is usually the end of the issue, but there are cases of 'spontaneous recurrence' of breast hematomas.
Hematomas need to be treated and closely followed because they do present risks for secondary health complications. While completely unrelated to cancer or anything of that nature, the pooled blood can become infected with bacteria, leading to inflammation, swelling, and fever. Skin discoloration is also a common side-effect. Special concern must be noted for women with any medical history of hemopathy and coagulation disorders, or those taking anticoagulant drugs. Some doctors might even suggest a patient keep away from certain pain killers (such as aspirin) which have been known to hinder the 'blood-clotting' process.
Hematomas are not related to breast cancer. They are caused be damaged blood vessels via surgery. But, it is quite important to get a clear differential diagnosis of hematoma if a patient is undergoing treatment for breast cancer. There are a couple of reasons for this. The asymmetric density and increased skin thickness that sometimes develops as the hematoma retreats often has a mammographic appearance that can mimick some breast carcinomas, so that has to be ruled out. Also, it is possible that an occult (hidden) breast tumor could be causing the internal bleeding. A hemorrage caused by an intracystic tumor (a breast-cancer growth growing in the middle of a cyst, surrounded by fluid) might also be a possibility, though rare.
Though hematomas following core biopsy procedures (for a suspected breast carcinoma) are quite rare, when they do develop it presents a certain pragmatic opportunity for subsequent surgical treatment. If the surgeons have decided to perform a lumpectomy, they can sometimes use a 'sonographically visible hematoma' (induced accidentally by the biopsy) as a localizing device and get very accurate surgical margins, and that's always a desired outcome in treating DCIS and breast cancer.