Leiomyoma of the breast
A leiomyoma is a benign tumor of smooth muscle cells (‘leio‘ means ‘smooth‘, ‘myo‘ means ‘muscle‘ and ‘oma‘ means ‘tumor‘). It is a benign lesion, which can occur in various places in the body, and very rarely occurs in the breast.
Leiomyomas are most common as uterine fibroids, and sometimes they occur in your muscles, occasionally in the gut.) A leiomyoma is often grouped along with an informal category of ‘stromal‘ tumors such as the solitary fibrous tumor and myofibrobastoma, which develop from immature muscle and connective tissue cells in subtle variations of presentation.
A leiomyoma is composed mainly of ‘mature‘ (well differentiated) smooth muscle cells. It is important to note that these neoplasms do not develop from either glandular or epithelial cells, which are a common source of many benign fibrocystic breast changes, and also breast cancer development. Typically, a breast leiomyoma will either develop from smooth muscle cells in the breast duct lining, or from smooth muscle elements of blood vessels. Leiomyomas are neither malignant nor premalignant, and more of an inconvenience than anything else.
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Slightly more common in women than men
Leiomyomas are slightly more common in females than males overall, and tend to develop later in life, often between 55 and 70 years of age. Breast leiomyomas tend to occur in the subareolar region (below the nipple), and for no known reason, they tend to occur most often in the right breast.
Breast Vascular leiomyoma (angioleiomyoma), and ‘cutaneous‘ leiomyomas
When the leiomyoma forms from smooth muscle tissue in the lining of blood vessels, the tumor is often referred to as a ‘vascular‘ leiomyoma. If the leiomyoma forms within the dermis (in any region of the body) it might be referred to as a ‘cutaneous‘ leiomyomas. These cutaneous (‘relating to the skin‘) tumors tend to be very small, and often occur in groups or multiples, and are more likely to be superficial and palpable.
Pathological features of breast leiomyoma
Leiomyomas which are visible or palpable may take on a yellow or yellowish-pink appearance. They also tend to be rather firm to the touch. The histological features of breast leiomyomas tend to be almost identical with leiomyomas occurring at other sites. Tumors tend to display bundles of ‘spindle-like‘ cells with ‘blunt‘ nuclei. The cytoplasm of leiomyomas is highly eosinophilic (stains readily for protein-sensing dyes), and stain positive for vementin, desmin, and especially smooth-muscle-specific actin.
Mammographically, the tumor will tend to show a sharply defined border and will lack the irregular and random appearances typical of breast carcinoma, but this possibility cannot be ruled out by X-ray alone. Breast leiomyomas usually appear homogeneous and moderately to highly dense. They are also ‘negative‘ for certain features which might suggest ductal carcinoma, such as microcalcification, architectural distortion, and skin thickening or nipple retraction. Sonographically, breast leiomyomas are mainly solid, homogeneous, and well circumscribed nodules, and without apparent cystic features (fluids). Leiomyoma also tends to very closely resemble fibroadenoma (also benign) on sonography and mammography, so a microscopic and histological evaluation is required. Once the biopsy sample has been analyzed, it is fairly easy to determine that a leiomyoma is not breast cancer. However, in terms of differential diagnosis, the most likely point of confusion surrounding a leiomyoma are the similarities to leiomyosarcoma of the breast (muscle cancer), which is prone to metastasis.
Treatment and management of breast leiomyoma
Leiomyomas can cause pain and swelling in the nipple-areola complex of the breast, so treatment basically revolves around the management of symptoms. If the tumor is not causing any problems, it might be left alone. Otherwise, it will usually be surgically excised. There is also some evidence to suggest that tamoxifen therapy (a chemical often used to treat various cancers) can cause leiomyomas in the breast to grow quickly and enlarge.
Here are the most popular Q&A’s about this topic…
- Where can leiomyoma be found? In the heart and uterus. A leiomyoma of the uterus is commonly called a fibroid.
- What causes leiomyoma? Genetic changes, hormones, and other growth factors.
- How common are leiomyoma? As many as 3 out of 4 women have this sometime during their lives, but most are unaware of them because they often have no symptoms.
- How to diagnose leiomyoma? Ultrasound and lab tests if you have symptoms. If a traditional ultrasound doesn’t provide enough information, your doctor may suggest MRI, hysterosonography, hysterosalpingography, myomectomy, or hysteroscopy.
- What are leiomyoma symptoms? Heavy menstrual bleeding, prolonged periods (7 days or more), pelvic pressure or pain, frequent urination, difficulty emptying your bladder, constipation, pain constantly with intercourse, backache or leg pains.
- What are the leiomyoma risk factors? There are few known risk factors such as heredity, race, menstruation at an early age, having a diet higher than red meat and lower in green vegetables and fruit, drinking alcohol including beer which appears to increase your risk.
- What are some leiomyoma complications? Although these aren’t usually that dangerous, they can cause discomfort and may lead to anemia, and heavy blood loss. These usually don’t interfere with conception and pregnancy. However, it is possible that these could cause infertility or pregnancy loss, prevention of implantation and growth of an embryo. As well as blocking fallopian tubes, or interference with the passage of sperm from your cervix to your fallopian tubes.
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