Firstly, the good news, hamartoma are benign lesions. Fibro-fatty tissues compose the breast hamartoma but often theses tissues are growing in an irregular way.
Although harmatomas may occur in the breast, they are common in other areas of the body as well. Because a breast harmatoma grows at the same rate as surrounding tissues, medics do not consider it to be a malignant tumor.
Hamartomas are mostly without symptoms and are often are only discovered accidentally on imaging studies for other reasons, such as screening. However, if the lump grows very large, it can cause cosmetic distortion of the breast shape. In these cases, surgeons will usually remove the lump.
The main concern about hamartoma is that it can present as either a palpable lump or an apparent breast mass on a mammogram (diagnostic chest x-ray), and this naturally leads to follow-up investigations to rule out possible breast cancer.
Other names for Breast Hamartoma
The term ‘hamartoma’, in the generic sense, indicates a tumor composed of several different types of normal tissue. Typically Harmatomas contain varying degrees of
- fibrous tissue
- glandular tissue
- fat tissue
but all growing in an unusual location and in a somewhat disorganized way. We often hear the term ‘fibroglandular’ breast tissue. This means a combination of fibrous tissue and glandular tissue supporting the breast lobules and other structures. The ‘glandular’ components of this connective tissue would be made of ‘adeno’ kinds of cells. In addition, the term ‘lipo’ refers to the fat components.
So, terms like
are really describing a hamartoma with respect to the cells that tend to be in a majority in that particular hamartoma.
Are all women prone to breast hamartoma development?
Hamartomas are in fact more prevalent amongst adolescent women. This may be due to imbalances in hormone levels during precocious puberty (early puberty). Also, hamartomas seem to grow faster during pregnancy and lactation.
Mammographic and microscopic appearance of Breast Hamartoma
On a breast X-ray the ‘classic’ appearance of a fibroadenolipoma will be a ‘lucent’ (see-through) area with smooth borders, consisting of both soft tissue (fibroglandular) and lipomatous (fat) elements. Sometimes, medics can describe a hamartoma as looking like a ‘slice of salami’.
On ultrasound a hamartoma will usually appear as a well-defined, solid, oval mass, quite similar visual acuity to the more common fibroadenoma It will usually reveal sonolucent fat and some echogenic fibrous elements, with a heterogeneous internal echo pattern. (In other words, the sonographic profile is kind of a mixed bag).
Specialists will also sometimes employ MRI imaging which tends to give a clearer picture of the internal fat densities, the smooth muscle cells and well-defined rim, and the heterogeneous internal elements.
Hamartomas lack a distinctive diagnostic appearance
In terms of its microscopic appearance and histology, breast hamartoma does not really have distinctive diagnostic properties. A pathologist might note fibrous tissue within the breast lobules, or fibrous tissue and fat in the supporting stroma with or without pseudo-angiomatous changes, (relating to blood vessels).
Commonly, hamartomas will appear as otherwise normal-looking breast tissue, but present in nodules within the fibrotic stroma surrounding and extending between individual breast lobules. Sometimes hamartomas can obliterate the normal ‘interlobular’ loose stroma. In the image of hamartoma below, the histology shows lots of fibrous tissue, with embedded islands of glandular cells, and fat around the outside (in the bottom-left).
These kind of features, in combination with mammogram and ultrasound images, and a clinical understanding of the age and context of the women in question, should suggest probable, and differential diagnosis of hamartoma. It is highly unlikely that any single diagnostic approach can confidently diagnose breast hamartoma.
Are Hamartomas worrisome in terms of possible breast cancer?
No, usually a breast hamartoma is a benign tumor, but, in rare instances, they can develop simultaneously with coincidental breast epithelial cell malignancy within the same lesion. So, it is possible that medics may dismiss a malignant tumor too quickly as just a hamartoma without full investigation.
If there is a distinct ‘lump’, and if there is evidence of asymmetrical breast density on the X-ray, this could suggest something more serious.
Incidence rate and treatment of breast hamartoma
Research studies estimate that breast hamartoma has an incidence rate between 0.1% and 0.7 %, which is very low. However, as more women participate in breast cancer screening programs, ct scans, and at earlier ages, the incidence rate may appear to rise.
Even though they are benign, the possibility that breast carcinoma may lie undiscovered within the epithelial elements of the hamartoma will likely lead to fairly intensive biopsy sampling. In addition surgical removal of the hamartoma may be necessary.
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