Adenoid Cystic carcinoma (ACC) of the breast
Adenoid cystic carcinoma of the breast is a rare form of breast cancer and it’s name derives from the microscopic appearance.
Cancer cells in adenoid cystic carcinoma are very similar in appearance to ‘adeno’ cells (the cells that create glandular secretions) and cystic cells.
Indeed, the name can be a bit confusing, as breast adenoid cystic carcinoma (ACC) is neither an adenoma, a breast fibroadenoma or a breast cyst. These conditions are benign and adenoid cystic carcinoma does not arise from these conditions.
Sometimes, specialists name this type of breast cancer ‘adenocystic breast carcinoma’. The good news is that medics consider adenoid cystic carcinoma to be a somewhat non-aggressive type breast carcinoma with a very good chance of full recovery.
With adenoid cystic breast carcinoma, lymph node involvement or metastases to distant areas is very uncommon.
Just letting you know that we have created a newer version of this page, with more up-to-date information on Adenoid cystic breast carcinoma. However, this page still has great reading material.
Breast adenoid cystic carcinoma is very rare and accounts for only about 0.2% of all breast cancers.
It tends to occur in postmenopausal women from the late 30’s right up into the 90’s. However, the average age for development of this cancer is between the late 50’s and mid 60’s. Adeno cystic breast cancer mainly affects women, but occasionally it develops in men as well.
Common Symptoms of Adenoid Cystic Carcinoma of the Breast
For most women, adenoid cystic carcinoma of the breast usually presents as a mass. Indeed, this mass or lump is often painful as well.
Even though breast adenoid cystic carcinoma frequently occurs in the subareolar region, nipple discharge is actually an uncommon symptom. The breast mass tends to develop over weeks to months, and typically there is no family history of breast cancer.
Because axillary lymph node metastasis is so rare, it is important to arrive at a diagnosis early in the presentation. Early discovery through breast cancer screening is always important for a better breast cancer prognosis.
However, in the case of adenoid cystic carcinoma, catching it before metastasis (or spread) provides extra assurance that the disease is treatable. Sampling of the axillary nodes by either fine-needle aspiration or core biopsy is rarely necessary with adenoid cystic breast cancer.
Mammographic findings typical of Adenoid Cystic Carcinoma of the Breast
Adenoid cystic carcinoma tends to develop a palpable mass, but also radiographers frequently find it on mammography. However, initial screening mammograms of potential adenoid cystic breast cancer tumors can be inconclusive and screening mammography often misses the tumor.
Radiological discovery of adenoid cystic carcinoma occurs in about 25% to 30% of cases. Adenoid cystic breast cancer tumors will tend to appear as developing asymmetric densities or irregular masses.
On ultrasound, adenocystic breast cancers will typically appear as as irregular, heterogeneous, or hypoechoic masses with minimal vascularity on color Doppler imaging.
MRI can actually be a useful diagnostic tool with adenoid cystic carcinoma of the breast. Due to the better soft-tissue contrast and dedicated multiplanar breast sequences, radiographers can often clearly see the full extent of the tumor.
Calcifications may develop in adenoid cystic breast cancer tumors, but mammograms rarely detect them.
Histological features characteristic of Adenoid Cystic Carcinoma of the Breast
With adenoid cystic carcinoma of the breast, traditional cytologic features of malignancy are generally not present. Tumor cells tend to be small, uniform, and monotonous, having very little cytoplasm, smooth chromatin, and just a few, if any, nuclei.
The diagnosis of adenocystic breast carcinoma is usually based on the presence of extracellular metachromatic spheres.
Breast Adenoid Cystic Carcinoma often presents in multilayered clusters
Syncytial, multilayered, and branching clusters of cells with a nuclear/cytoplasmic ratio tend to comprise adenoid cystic carcinoma of the breast .
Microscopically, adenoid cystic carcinoma appears highly cellular and usually contains extra cellular spheres of metachromatic material surrounded by uniform cells with scant cytoplasm. Spherules of adenoid cystic carcinoma of the breast are typically surrounded by several cell layers.
Adenoid cystic carcinoma is typically composed of basaloid cells outlining spaces containing basal-like material and of eosinophilic cells lining true glandular lumina.
So, an adenoid cystic carcinoma lesion will typically have an invasive proliferation of circumscribed nests, and islands. Also, there may be cord-like clusters of tumor cells. These cord-like custers can form into either cribriform, tubular, or solid arrangements.
Two different cell types compose the ‘tumor islands’. There is usually a basaloid cell population which predominates, and then a smaller population of cells which feature bright eosinophilic cytoplasm.
Myoepithelial origin of adenoid cystic Carcinoma of the Breast is possible, but not confirmed
The cribriform spaces or lumens of adenocystic breast carcinomas are usually filled with basement membrane material, mucoid secretions, or possibly an eosinophilic band deposited on the luminal surface of the cells.
Many adenocystic breast tumor cells contain densely packed fibrils, which might suggest a myoepithelial origin for this type of breast cancer.
So, while it is quite likely that the basaloid cells have a myoepithelial derivation, there is a still a lack of ultrastructural evidence to support this assertion.
The smaller, eosinophilic cell populations usually show prominent desmosomes and luminal microvillous projections, and this appearance is highly suggestive of adenosquamous cells.
Often ER and PR negative
In terms of the immunohistochemical profile of adenoid cystic carcinoma of the breast, one usually sees a variably positive reaction for actin and S-100.
In addition, the eosinophilic components will show a positive reaction for cytokeratin. Estrogen and progesterone receptor positivity is usually negative with adenoid cystic breast cancers. That is, ER and PR receptors are usually present, but only in relatively small quantities and only in around 40% of tumors.
Grading of Adenoid Cystic Carcinoma of the breast
Specialists base the grading of adenoid cystic breast carcinomas on the relative amount of solid versus cystic areas of the tumor. However, this is unusual because it is the atypical cellular features that doctors use to grade most other breast cancers.
Grade I adenoid cystic breast tumors basically do not have a solid component. However, grade II tumors have a solid area of less than 30% of the total tumor mass.
Adenoid cystic carcinoma of the breast in which the solid component comprises more than 30% of the total tumor are classified as grade III.
Treatment and Prognosis for Breast Adenoid Cystic Carcinoma
A simple or modified radical mastectomy is the treatment of choice for the majority of patients with adenoid cystic breast cancer However, sometimes a lumpectomy is the treatment, but this is for a minority of patients.
However, studies show that local excision of the tumor has unacceptably high rates of cancer recurrence. Most patients receive radiation therapy after surgical removal of adenocystic breast cancer tumors.
As the rate of metastasis for adenoid cystic breast carcinoma is known to be extremely low, (estimated at only around 2%) axillary lymph node dissection is generally not helpful in clinical management.
When distant metastases do occur with adenocystic breast cancers, they tend to do so without any prior lymph node involvement. The lung, in fact, is by far the most common site for rare metastasis of adenoid cystic breast cancers. Not all cases of adenocystic breast carcinoma are estrogen or progesterone positive, but some do demonstrate a high level of hormone sensitivity, and can effectively treated with chemotherapy.
The prognosis for adenoid cystic breast cancer is excellent
Long term follow up is necessary with adenoid cystic breast cancer, but overall the outlook is excellent and one can have high expectations for a full recovery.
Of course, the lower the tumor grade, the prognosis becomes even more encouraging. The five year disease free survival rate of adenoid cystic breast cancer is basically 100%, and the five year overall survival rate may be estimated at about 85% (most likely due to causes unrelated to breast cancer).
Below are a few common Q&A’s…
What are the signs and symptoms of adenoid cystic carcinoma of the Breast?
Adenoid cystic breast carcinoma may be quite small or it can be large enough to be felt as a breast lump, which sometimes causes swelling and breast pain. The size of an adenoid cystic breast carcinoma can vary from 0.5 cm to 20 mm.
What are some tests used to diagnose adenoid cystic breast cancer?
- Breast ultrasound
- Breast biopsy
- Sentinel lymph node biopsy.
The treatment for adenoid cystic carcinoma is very effective with little risk of recurrence. So ACC has an excellent outlook for complete recovery.
Does adenoid cystic breast cancer spread to the lymph nodes?
Most cases of adenoid cystic of the breast does not spread to the lymph nodes and rarely metastasizes to other parts of the body. Not all cases of ACC are fuelled by estrogen or progesterone, but some may be hormone-sensitive.
How is adenoid cystic breast cancer treated?
- Radiation therapy
- Hormone therapy
- Glazebrook KN, Reynolds C, Smith RL, Gimenez EI, Boughey JC.
(2010) Adenoid Cystic Carcinoma of the Breast. Am. J. Roentgenol. 2010;194:1391-1396 https://www.ncbi.nlm.nih.gov/pubmed/20410430
- Muslimani A, Ahluwalia M, Clark C, Daw H. (2006) Primary adenoid cystic carcinoma of the breast: case report and
review of the literature. International Seminars in Surgical Oncology 2006, 3:17 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1526742/
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