Adnexal carcinoma of the breast
Adnexal carcinoma is a kind of cancer that either arises from or resembles the sweat or sebaceous glands. Microcystic adnexal carcinoma is a rare malignant tumor which is essentially of sweat gland origin. It is a slowly progressing tumor, which is mostly associated with the skin, and not the breast duct tissues. However, as there are some of the adnexal glands in the breast, microcystic adnexal carcinoma has been known to occur in the breast. However, it is not really considered a kind of ‘breast cancer‘ per se, but rather a skin cancer which has either grown in the skin of the breast, or metastasized to the region. However, a woman undergoing a clinical evaluation of an unusual lesion or ‘lump‘ on her breast and concerned about potential breast cancer may discover that the lesion is in fact a microcystic adnexal carcinoma.
This page is a little bit old, but still has great information. We have created a newer page involving Adnexal carcinoma, but it’s pretty short, so I would still use this one.
Adnexal breast cancer is really a ‘skin cancer’
Adnexal carcinoma of the breast (which is really a skin cancer growing on the breast) is often misdiagnosed in both the clinical and histological settings. Clinically it usually presents as a firm subcutaneous nodule, which is often pale yellow and with overlying telangiectasias (dilated superficial blood vessels, appearing as ‘red spots‘). Most commonly, adnexal carcinoma occurs in the face, head, and neck, but rarely it does occur on the breast. An adnexal carcinoma of the breast might also present as a cyst, and frequently can be present for many years before being screened as a potential breast cancer. Adnexal carcinomas are usually without symptoms, and that is why they tend to be ignored. Occasionally, they may create symptoms of numbness and burning, even paresthesia, but not very often. They are generally considered a benign carcinoma, but there is a small possibility of malignancy and lymph node metastasis.
Subtypes of adnexal breast carcinomas may include Trichoepithelioma, Syringomas, and hidradenocarcinoma
There are various subtypes of adnexal carcinomas which may occur on the breast:
A ‘trichoepithelioma‘ is a benign epithelial tumor which develops from the hair follicles. Some people consider a trichoepithelioma to be a poorly differentiated hamartoma of the hair germ. These lesions are most common on the face, naturally, but could develop on the breast.
A ‘syringoma‘ is another harmless sweat duct tumor, which is usually found on the eyelids. However, they can occur on the breast. Syringomas are usually either yellow or skin-colored firm rounded bumps, and very small, only 1-3 mm in diameter.
‘Hidradenocarcinoma‘ is another kind of adnexal carcinoma which is derived from the epithelial cells of sweat glands. The term is sometimes also used in a general sense to describe all skin tumors which have a resemblance to the epithelial elements of sweat glands.
Infiltrating syringomatous adenoma (ISA) of the breast is another term of microcystic adnexal breast carcinoma
Infiltrating syringomatous adenoma (ISA) of the breast is another term that is often used interchangeably with microcystic adnexal carcinoma. Sometimes the lesion is also referred to as a well-differentiated adenosquamous carcinoma, or simply as a sclerosing sweat duct. Microcystic adnexal breast carcinomas, or infiltrating syringmatous adenomas of the breast can often be confused with a well-differentiated tubular carcinoma of the breast. Both kinds of tumors have a pattern of infiltration which tends to invade the surrounding nerves and smooth muscle tissue. However, the presence of aquamous metaplasia in the adnexal breast carcinoma will differentiate it from a tubular breast carcinoma.
Adnexal Carcinomas frequently occur in the ovaries, as a metastasis of breast cancer
Adnexal carcinomas are quite frequently associated with a cancer metastasis to the ovaries. It is estimated that about 35% of ovarian metastasis of carcinoma are from from breast cancers. In some studies, the figure is a bit higher, suggesting that about 50% of ovarian cancers are due to breast cancer metastasis. However, not all neoplastic growth in the ovaries are malignant carcinoma. About 75% of lesions which develop in the ovaries in women who have breast cancer turn out to be benign adnexal masses. So, overall, the rate of metastasis of carcinoma which actually develops in the ovaries from breast cancer is very small, and is a reflection of an advanced progression of the breast cancer.
Metastasis to the ovaries is a possibility
The average interval between the diagnosis of breast cancer and a metastasis to ovarian carcinoma is just under one year, and the average survival time once ovarian metastasis has occurred is estimated at about 16 months. However, it must be remembered that metastasis of breast cancer to the ovaries is still very unlikely, and it is far more likely that a neoplastic grows in the ovaries will turn out to be a benign adnexal tumor.
Mammographic features typical of an adnexal breast carcinoma
If a microcystic adnexal carcinoma develops in the breast, it will likely appear mammographically as an ill-defined spiculated mass, perhaps with some smudgy areas of infiltration. However, there are no specific radiological features of an adnexal breast carcinoma/infiltrating syringomatous adenoma which would distinguish it from conventional breast carcinoma. The actual location of the tumor, however, might be a clue. Microcystic adnexal carcinomas occur in the skin of the breast and as such will tend to be towards the peripheries.
Histological features common to breast adnexal carcinomas
Microscopically, a microcystic adnexal breast carcinoma will likely feature a stratified proliferation of microcysts, cords, and ducts of cells showing squamous or adnexal differentiation. The tumor will often extend beyond the clinical margins with local spreading in the dermal, subcutaneous, and perineural tissues (into the underlying muscle). Histologically, a microcystic adnexal breast carcinoma may exhibit both pillar and sweat duct differentiation, with a stroma of dense collagen. If a glandular component is particularly prominent, the tumor might be classified as a sclerosing sweat duct carcinoma or possibly a malignant syringoma. Of note, cellular atypia, mitoses, and also necrosis, are almost completely absent from breast adnexal carcinomas.
Adnexal breast carcinomas tend to show cysts filled with keratin
Frequently, the ‘deeper‘ component of a microcystic adnexal breast carcinoma will have a schirrous appearance which shows small nests and strands of cells within a dense, hyalinized stroma. Epithelial elements are often somewhat diminished in number, to small clusters of just 2 or 3 cells. Cytologically, the tumor cells are usually of a uniform size. And, characteristically, an adnexal breast tumor will usually exhibit keratin-filled cysts, and nests and cords of ‘basaloid‘ cells, which may invade deep into the dermis to the subcutaneous fat.
Immunohistochemical staining is an integral part of diagnosis
The histological evaluation is an important part of the differential diagnosis, which might consider alternative diagnoses of adenosquamous carcinoma, squamous cell carcinoma, morpheaform basal cell carcinoma, and possibly metastatic breast carcinoma. Immunohistochemically, the tumor cells also tend to stain positive for EMA and various cytokeratins (especially CK7). Microcystic adnexal carcinomas have been shown to commonly express p63, usually in more than 75% of the cells. S-100 positive cells are also frequently present, but the stroma will tend to be CD34 negative.The luminal cells of a microcystic adnexal breast carcinoma will typically express CEA. A low level of Ki 67 in an adnexal breast carcinoma would typically indicate a low proliferative index.
Treatment and Prognosis for breast adnexal carcinomas
Microcystic adnexal breast carcinomas are essentially a form of skin carcinoma, which can occur in the breast. It is considered to be a benign form of carcinoma, but is treated with a wide surgical excision because of its ‘locally agressive‘ behavior. In other words, it has a high rate of local recurrence, sometimes as high as 45%. It is a very slow growing tumor, but re-excision is still often required. Overall, the 10 year rate of recurrence for a microcystic carcinoma of the breast may be estimated at around 18%.
Malignancy is rare in microcystic adnexal breast carcinomas. Once the tumor has been excised, routine follow up is mandatory, and a sentinel lymph node biopsy might be recommended. Generally speaking, the single most important prognostic factor for predicting breast cancer survival is the status of the lymph nodes. Routine staining of a tumor-site biopsy sample has only a 1% chance of finding a tiny focus of metastatic breast cancer smaller than 3 cell diameters, so, a sentinel node biopsy might be a prudent management approach.
It is always a good idea to have any curious skin lesion or bump on the breast examined for potential breast cancer. Adnexal carcinoma is slow growing and benign and frequently ignored. The potential for malignancy is small, but better to have it checked and removed just to be sure.
Below are some Q&A…
- What are the two suspected risk factors for adnexal carcinoma? Unprotected sun exposure and previous radiation therapy are the two most suspected risk factors.
- Where else can this tumor spread to? This type of tumor rarely metastasizes to other parts of the body, but it can grow large and penetrate fat, muscle and other tissues as well. It can also affect a wide range of patients, though the average age of diagnosis is 56.
- What does adnexal carcinoma look like? Adnexal carcinoma first appears as a smooth, slightly raised bump or patch. It can be flesh-colored or yellow.
- What are the known symptoms that are associated with adnexal carcinoma? While the tumor can grow over time, it might not cause any problems for years until it interferes with nearby nerves that can lead to discomfort, numbness, tingling, burning and/or itching.
- How is adnexal carcinoma diagnosed? This tumor is difficult to distinguish from other conditions. Cancer specialist may recommend biopsy and or MRI.
- How is adnexal carcinoma treated? Mohs micrographic surgery is the main treatment for adnexal carcinoma. Radiation therapy is also sometimes used either with surgery or (rarely) as a stand-alone treatment.
- What causes adnexal carcinoma? Because the tumor most often occurs in whites and in areas that are most exposed to the sun (the face), sun exposure is thought to contribute to the onset of adnexal carcinoma. It often is found on the left side of the face, the part of the face that would be exposed to the sun while driving. However, somewhere between 20% and 50% of those with adnexal carcinoma also had previous radiation treatment for a previous condition, therefore, this may also contribute to the development of the tumor.
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