Spindle cell Lipoma of the breast
A spindle cell lipoma is a rare variant of a benign breast lipoma.
So, the characteristics of a spindle cell lipoma of the breast include a mixture of:-
- mature fat cells
- collagen-forming spindle cells
- varying degrees of myxoid change (myxoid means containing mucus)
These lesions were first described in 1975 and are most common in the subcutaneous tissue of the upper back and shoulders of males, but have been known to occur in the female or male breast as well.
This page is getting somewhat old, but don’t get me wrong, it is still very useful and I would still use it. However, I have a newer page with more up-to-date information on benign breast conditions, including Spindle Cell Lipoma of the Breast.
Spindle cell lipomas tend to develop in individuals over the age of 40, with an average age of around the mid-50’s. The rate at which spindle cell lipomas develop in the breast of both men and women is approximately equal. However, overall spindle cell lipomas are much more common in men.
A bit more about the Spindle Cell Breast Lipoma
The composition of all spindle cell breast lipomas is some combination of the following cells:-
- bland spindle cells
- mature adipocytes
- collagen bundles.
Specialists sometimes call a breast spindle cell lipoma a ‘benign stromal spindle cell tumor with a predominant adipocytic component’.
Most spindle cell breast lipomas are benign, but not all of them. However, within the benign group, their appearance may at times mimic malignant breast cancer, so they require a thorough, conservative approach to diagnosis and management.
Potentially malignant features of spindle cell breast lipoma
One common feature to all breast spindle cell lipomas is the presence of spindle cells without epithelial cells. Benign spindle cell lipomas tend to have a very bland appearance. There is a varied mixture of spindle and oval cells with bland nuclei, inconspicuous nucleoli, and a very low rate of cell mitosis. A benign spindle cell lipoma will also not show signs of necrosis.
A malignant spindle cell breast lipoma (which really means it is something else and not a spindle cell lipoma) may show a range of atypical features. These features include:-
- discohesive cells with mitotic activity
- cell necrosis in the background
- nuclear atypica
- abnormal mitosis
- a myxoid stromal background is also a bit more worrisome for malignancy.
‘Myxoid’ substances show an overproduction of mucopolysaccharide substances, and are characterized by a loose pale-to-light staining profile. Myxoid substances appear as a thin, amorphous and semitransparent substance. Specifically, myxoid background substances contain glycosaminoglycans, both sulphated (chondroitin sulphate, keratan sulphate) and non sulphated (hyaluronic acid).
Some features are similar to malignant breast myoepithelioma
Potentially malignant breast tumors which have similar features to breast spindle cell lipoma would include:-
Mammogram and ultrasound evaluation of breast spindle cell lipoma
A breast spindle cell lipoma usually appears on a mammogram as a well-circumscribed mass. On ultrasound, a spindle cell lipoma of the breast will usually be seen as a homogeneously hyperechoic mass or nodule, primarly solid and with a low echogenicity shell.
Sonogram features of breast spindle cell lipomas can share some characteristics with hamartoma and other benign breast tumors, so fine needle biopsy is usually necessary for further investigation, at the very least.
Typical histological features of breast spindle cell lipoma
So, a typical benign spindle cell lipoma of the breast will contain somewhat uniform spindle cells together with thick collagen bundles and mature adipocytes. Sometimes they can appear ‘entrapped’ within normal breast ducts, lobules, blood vessels, and nerves. So, this can be confusing to medics as it gives the false appearance of an aggressively infiltrating tumor.
Breast spindle cell lipomas will typically be immunoreactive to CD34 and vimentin. However, a spindle celll lipoma of the breast will be non-reactive for:-
- smooth muscle actin
- Factor VIII
So this can help solidify the diagnosis.
Spindle cell breast lipomas can grow quite large
Most spindle cell breast lipomas are between 3 cm and 5 cm in diameter, but they can grow to be very large (up to 14 cm). Most spindle cell lipomas are composed of a relatively equal ratio of fat and spindle cells, but actually either component may predominate.
Treatment and follow-up for spindle cell lipoma of the breast
Given the fact that spindle cell lipoma can resemble quite a large number of both benign tumors (such as myofibroblastoma of the breast and breast leiomyoma) and malignant breast tumors, (such as leiomyosarcoma) it is very unlikely that a diagnosis will be possible on the basis of clinical exam and mammography alone.
A fine needle biopsy is usually undertaken to get a sense of whether or not there are any of the atypical or myxoid features described above. If these features are present, even to a very small degree, a wide excisional biopsy will almost certainly be undertaken.
Benign spindle cell breast lipomas will probably be managed with routine follow-up evaluations. However, treatment for those with a malignant or potentially malignant profile will most likely be complete surgical removal.
For further reading, I suggest you visit this page with some information on lipoma of the breast, go to this page with spindle cell carcinoma of the breast, as well as this page, for breast adenocarcinoma with spindle cell metaplasia.
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