A lipoma is a benign tumor of the breast. So, fat tissue is the main component of a lipoma.
Essentially, a lipoma is a pocket of fat that is encapsulated by a thin fibrous capsule. Lipomas are very common and can occur in many areas of the body. However, most frequently lipomas appear in the gastro-intestinal tract.
Do not worry, lipomas of the breast are not cancerous or pre-cancerous. Furthermore, lipomas do not increase the risk for breast cancer in any way.
Lipomas are slow growing tumors and mostly occur in adults between the ages of 40 and 60 years old, but they can also occur at any age, including in children.
Breast lipomas, however, occur more commonly in post-menopausal women.
Discovery of breast lipomas
Often, women will discover a lipoma of the breast herself and seek medical attention from their family physician. Next the family doctor will likely initiate breast cancer screening procedures, a mammogram or an ultrasound.
Most breast lipomas are painless, soft to the touch, and movable. They tend to be quite small (less than 1 cm), but can grow up to 6 or more cm in diameter.
However, breast lipomas are not always clinically palpable. Radiographers will discover some breast lipomas through breast cancer screening mammography.
Breast lipomas also tend to be solitary tumors. Most breast lipomas are small, weighing only a few grams. A breast lipomas which is larger than 5cm and weighs more than 500g is sometimes called a giant breast lipoma.
Breast lipomas can be difficult to diagnose
Breast lipomas are not always easy to diagnose right away. This can cause an increase in anxiety for possible breast cancer.
The presence of a painless lump in an older, adult woman does have the potential to be breast cancer. Indeed, both mammography and ultrasound are not always able to distinguish breast lipoma from breast carcinoma.
In addition, fine needle biopsies can often lead to confusing diagnostic results. The results may depend on the sample, that is which part of the lipoma the surgeon removes for testing.
Unfortunately, excisional biopsy is a requirement to properly diagnose breast lipoma. Interestingly, only about 11% of breast lipomas present in a ‘classic’ pattern. On average, about 25% of lipomas are under-diagnosed.
Mammographic and histological evaluation of breast lipomas
A breast lipoma is a fat cell neoplasm that starts with one cell that grows and divides too rapidly, more than its neighbors. So, essentially the microscopic evaluation should show primarily fat cells.
Histopathologic examination of breast lipomas often reveal well encapsulated nodules of mature adipocytes, typically separated by fibrovascular septae.
Breast lipomas are frequently found both with and without normal epithelial cells. Unless there is evidence of atypical nuclei and cell formations, then the lipoma is almost certainly benign in nature.
Lipomas of the breast typically show no suspicious mammographic features
Mammogram and breast ultrasound will typically show no suspicious features with a breast lipoma. Indeed, breast lipomas usually present as a well-circumscribed, smooth or lobulated mass.
Lipomas usually show on breast X-ray as a translucent or ‘radiolucent’ grey mass surrounded by a radio-opaque capsule.
Follow up evaluation in a few months is usually a sufficient management approach for lipoma of the breast. The exception to this is if the lipoma is a very large tumor or if it has increased in size from a previous scan.
A radiologist will diagnose most breast lipomas using common sense and evidence from the ultrasound and mammogram results. If the imaging results suggest that the lump is probably a lipoma, biopsy is not necessary.
There are 3 typical sonographic appearances of breast lipomas. So,they can be:-
- Completely isoechoic to surrounding normal fat lobules
- Mildly hyperechoic to nearby normal fat lobules
- Isoechoic in comparison to adjacent fat lobules and containing numerous thin, internal echogenic septa.
Sometime ultrasound can help demonstrate the ‘softness’ of a breast lipoma, by documenting a decrease in the anterior-posterior measurement of the breast mass with mild transducer pressure.
Treatment and management of breast lipomas
The most likely treatment for a breast lipoma, if there are no suspicious features on mammogram, is to leave it alone. A follow-up clinical and mammographic evaluation in about 6 months is necessary.
Medics will delay the decision to biopsy until there is some evidence of suspicious change. This is because both physicians and patients usually prefer not to biopsy breast lesions that are highly likely to be benign.
However, if a suspected breast lipoma appears to grow rapidly during the observation period, surgical removal is necessary. Some research sources claim that malignant transformation my occur within a breast lipoma, but this has yet to be proven convincingly.
See also our page on:-
- Bancroft LW, Kransdorf MJ, Peterson JJ, O’Connor MI. (2006) Benign fatty tumors: classification, clinical course, imaging appearance, and treatment. Skeletal Radiol. 35 (10): 719–33. https://www.ncbi.nlm.nih.gov/pubmed/16927086
- Lanng C, Eriksen BO, Hoffmann J. (2004) Lipoma of the breast: a diagnostic dilemma. The Breast (October 2004) Volume 13, Issue 5, Pages 408-411 https://www.ncbi.nlm.nih.gov/pubmed/15454196
- Ribeiro RC, Saltz R, Quintera LFE. (2008) Breast Reconstruction with Parenchymal Cross After Giant Lipoma Removal. Aesthetic Plastic Surgery, (May 2008)Volume 32, 4., p. 695-697 https://www.ncbi.nlm.nih.gov/pubmed/18498011
- Delli Santi G, Bellioni M, Loreti A, Stagnitto D, La Pinta M, Dell’Osso A. (2006) Giant breast lipoma: a rare cause of breast asymmetry. Plast Reconstr Surg 2006 Mar; 117 (3) : 1068-9.
- Lopez-Rios F, Alberti N, Perez-Barrios A, de Agustin PP. (2000) Aspiration biopsy of pleomorhiclipoma of the breast. A case report. Acta Cytol 2000; 44 (2) : 255-8.
- Miettien MM, Mandhal M. (2002) Spindle cell lipoma, pleomorphic lipoma. In Tumours of soft tissue and bone. Edited by: Fletcher CDM. WHO classification of tumors. IARC Press; 2002. http://surgpathcriteria.stanford.edu/softfat/spindle_cell_lipoma/printable.html
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