Breast adenomyoepithelioma
Adenomyoepithelioma of the breast is considered a ‘biphasic‘ neoplasm, which means it features a combination of epithelial cell and myoepithelial cell elements. Epithelial cells are normally associated with tissues such as skin and membranes, while myoepithelial cells tend to be associated with muscle tissue. Most breast cancers arise in the breast ducts, which are primarily made primarily of epithelial cells.
This page is getting somewhat out-of-date, but don’t get me wrong, it is still very useful and I would still use it. However, I have created a newer version of this page with more up-to-date information on Breast Adenomyoepithelioma.
A breast adenomyoepithelioma usually presents has a palpable mass, prompting screening evaluation for breast cancer. However a breast adenomyoepithelioma is considered to be a benign neoplasm. It has to be removed surgically, and that usually provides a final cure.
There is some evidence of local recurrence, but generally a breast adenomyoepithelioma does not undergo a malignant transformation and metastasize, though this has happened on occasion. One would have to say that for an adenomyoepithelioma of the breast, there is a ‘spectrum‘ of possibly disease behaviors. They are mostly benign, but with some potential for local recurrence and, rarely, distant metastasis.
Adenomyoepitheliomas are uncommon
Breast Adenomyoepitheliomas are quite uncommon, and tend to happen in older women. The average age for developing an adenomyoepithelioma of the breast is about 60 years. Some physicians consider a breast adenomyoepithelioma to be a variant of an intraductal papilloma. It also seems to be closely related to a clear cell hidradenoma of the breast.
Breast Adenomyoepitheliomas are often given ‘subcategories‘
Adenomyoepitheliomas of the breast can often be sub categorized into one of three types. These include tubular breast adenomyoepithelioma, lobulated breast adenomyoepithelioma, and spindled breast adenomyoepithelioma. The subtype distinction will largely depend upon the type of cell which seems to be a somewhat more prominent in the lesion than others.
‘Tubular breast adenomyoepithelioma‘ is the most common subtype, and it is characterized by a proliferation of glandular cells and surrounding myoepithelial cells with abundant clear cytoplasm.
Clinical and mammographic features of a breast adenomyoepithelioma
Breast adenomyoepitheliomas will usually presents as a solitary unilateral painless mass. Often they occur at the breast periphery, but do present in other regions as well. On mammography, a breast adenomyoepithelioma will probably appear as an opaque mass, and often with linear microcalcifications. The margins may be blurred here and there.
On ultrasound, and adenomyoepithelioma of the breast will probably appear as a hypoechoic tumor with microcalcification.
Microscopic and histological features of adenomyoepithelioma of the breast
Upon microscopic evaluation, a breast adenomyoepithelioma may be observed as glandular structures which are formed by an inner layer of epithelial cells, and by an outer layer composed of of myoepithelial cells.
The inner ‘adeno‘ or granular element will tend to have eosinophilic cytoplasm, while the outer myoepithelial cell layer will tend to have clear cytoplasm. The myoepithelial cells in a breast adenomyoepithelioma will tend to stain positive for calponin. One will often see tubules lined by the cuboidal or columnar epithelial cells.
Sometimes these columnar epithelial cells are pushed to the edge of the nodule, or they might be ‘compressed‘, appareling similar to multinucleated giant cells. Quite often, there is also an apocrine cell element to these lesions as well.
Benign breast adenomyoepitheliomas may exhibit mildly atypical features
The myoepithelial cell component of a breast adenomyoepithelioma tends to be expanded and prominent. They often form into ‘polygonal‘ structures, and have clear cytoplasm. They often have elements that resemble ‘spindle cells‘.
There are usually no mitotic figures and no necrosis, but sometimes they do appear, making the legion more suspicious of malignancy. A breast adenomyoepithelioma may have mild to moderate nuclear atypia as well.
Positive for smooth muscle actin
Immunohistochemical staining of a breast adenomyoepithelioma will usually show positively for smooth muscle actin, weakly positive for S-100, and most often negative for cytokeratin.
Differential Diagnosis for breast adenomyoepithelioma
It is quite easy to misdiagnose a breast adenomyoepithelioma. They are often difficult to distinguish from a sclerosing adenosis, fibroadenoma, or a tubular adenoma. However, these other potential tumors will typically have less prominent proliferative features compared with adenomyoepithelioma chondroid and osseous differentiation.
Treatment and prognosis of breast adenomyoepithelioma
Generally speaking the prognosis for women with breast adenomyoepitheliomas is good. But, it is important that the surgeon is able to achieve a good margin when removing the tumor. Local recurrence and malignant transformation are not uncommon.
The most important thing is to determine as clearly as possible, early on in the diagnosis, whether or not the breast adenomyoepithelioma has the potential for malignancy. The most important predictors of malignancy are cytologic atypia, a high mitotic rate, and an infiltrative peripheral border.
Malignant breast adenomyoepitheliomas rarely metastasize
Malignant breast adenomyoepitheliomas tend to be of a low grade. Axillary node metastasis has been rarely reported with breast adenomyoepithelioma, with very rare distant metastasis to the lung and brain. Malignant transformation may occur one or both cell types, but is generally thought to be associated with hematogenous, rather than lymphatic, metastasis.
Treated with surgical excision
Breast adenomyoepitheliomas are generally treated successfully with surgical excision. Where there is local recurrence, they may be treated with radiation therapy, or possibly with mastectomy.
For further reading, I suggest you go to this page for breast myoepithelioma, visit this page for adenosquamous breast cancer, go to this page with information on adenocarcinoma of the breast, as well as this page which has material on breast adenoma.
References
- Howlett DC, Mason CH, Biswas S, Sangle PD, Rubin G, Allan SM. Adenomyoepithelioma of the breast: spectrum of disease with associated imaging and pathology. AJR Am J Roentgenol. 2003 Mar;180(3):799-803.
- Chu, PY., Cheng, TF., Teng, TH., Lee, CC. Adenomyoepithelioma of the Breast — A Case Report. Tzu Chi Med J 2006. Vol. 18, no.1 p. 65-67.
- Ahmed AA, Heller DS: Malignant adenomyoepithelioma of the breast with malignant proliferation of epithelial and myoepithelial elements: A case report and review of the literature. Arch Pathol Lab Med 2000; 124:632-636.
- Kiaer H, Nielsen B, Paulsen S, Sorensen IM, Dyreborg U, Blichert-Toft M: Adenomyoepithelial adenosis and low-grade malignant adenomyoepithelioma of the breast. Virchows Arch A Pathol Anat Histopathol 1984; 405:55-67.
- Berna JD, Arcas I, Ballester A, Bas A: Adenomyoepithelioma of the breast in a male. AJR Am J Roentgenol 1997; 169:917-918.
- Choi JS, Bae JY, Jung WH: Adenomyoepithelioma of the breast—its diagnostic problems and histogenesis. Yonsei Med J 1996; 37:284-289.
- Tavassoli FA: Myoepithelial lesions of the breast. Myoepitheliosis, adenomyoepithelioma, and myoepithelial carcinoma. Am J Surg Pathol 1991; 15:554-568.
- Loose JH, Patchefsky AS, Hollander IJ, Lavin LS, Cooper HS, Katz SM: Adenomyoepithelioma of the breast. A spectrum of biologic behavior. Am J Surg Pathol 1992; 16:868-876.
- Tavassoli FA: Myoepithelial lesions of the breast. Myoepitheliosis, adenomyoepithelioma, and myoepithelial carcinoma. Am J Surg Pathol 1991; 15:554-568.
- Zarbo RJ, Oberman HA. Cellular adenomyoepithelioma of the breast. Am J Surg Pathol. 1983;7:863–870.
- Finck FM, Schwinn CP, Keasby LE. Clear cell hidradenoma of the breast cancer. 1968;22:125–135.
- Ocak, I., Hammerman, S., Lacomis, J., Metastatic transformation of benign breast adenomyoepithelioma. European Journal of Radiology Extra Volume 69, Issue 3, March 2009, Pages e93-e96
Back to Types of Lesions List or to the brand new Breast Cancer Homepage.
