Signet Ring Cell carcinoma of the Breast
Signet ring cell breast carcinoma as a whole was originally groups classified as a variation of mucinous carcinoma, but was later recognized as a distinctive cancer subtype. The most striking feature of signet-ring cell carcinoma, aside from the characteristic ‘signet-ring‘ shape of the cells involved, is the abundant accumulation of intracellular mucin. Signet ring cell carcinoma of the breast accounts for between 2% and 4.5% of all breast cancers.
I would like to inform you that I have created a newer version of this page with more up-to-date information on Signing Ring Cells in Breast Cancer. However, this page is still great for research material, and so because of that, I would still use it as well.
In terms of clinical presentation, the average age of patients with signet ring cell carcinoma of the breast tends tend to be a little older than for other breast cancers. Quite often, women with signet ring cell breast cancer also present with a more advanced disease state.
Signet ring cells occur in various types of cancer, not just breast cancer
Signet Ring cells can actually occur in many different types of cancer tumors. Signet-ring cells tend to arise in tumors originating in glands. When a cancer pathologist sees signet ring cells in a breast tumor, they tend to immediately think of lobular breast carcinoma rather than ductal carcinoma.
Sometimes signet-ring cell breast carcinoma is misdiagnosed
It is quite easy to either miss or dismiss the diagnosis of signet ring cells in a tumor because they are very small and often seem inconspicuous in the tissue. For patients with lobular carcinoma, the doctors will usually have a close inspection of the lymph nodes, and that’s one place they can usually find signet ring cells when they are associated with the disease.
Signet-ring cell carcinoma of the breast is a subtype of adenocarcinoma
Signet-ring cell breast carcinoma is really a unique subtype of mucin-producing adenocarcinoma, and as such care arise in virtually any organ. Breast, stomach, and colon signet-ring cell carcinomas nonetheless comprise about 90% of all cases of this particular cancer subtype. A majority of breast signet-ring cell carcinomas are in fact infiltrating lobular carcinomas, though ductal carcinomas are not uncommon.
Diagnosis of breast signet ring cell carcinoma
Signet-ring cell carcinoma is given the name because when viewed under a microscope the cells look like a signet ring. The nucleus appears to be ‘pushed over‘ (kind of like a stone in a ring) while the remainder cell membrane forming the outside ‘ring‘ shape. The cells are small and uniform usually. They are composed of a clear vacillated cytoplasm with a compressed nucleus situation at the bass of the cell. Signet ring cells can take up as much as 99% of a breast cancer lesion, but often occur in a lesser proportion.
The amount of signet ring cells thought to be ‘significant‘ enough to call the tumor a signet ring cell lesion is a little bit of a judgement call. Some people still use the term signet ring cell carcinoma when there are as little as 20% signet ring cells. Generally speaking nowadays the term signet ring cell breast carcinoma would not be used unless the signet ring cells comprise between 20% and 50% of the tumor mass, and 50% seems to be the most commonly used figure. The specific label would of course depend upon other findings and characteristics of the tumor.
Metastasis shows a unique aspect of signet ring cell carcinoma of the breast
One of the unique aspects of breast signet-ring cell carcinoma is its pattern of metastasis. A significantly greater number of metastatic breast signet ring cell carcinomas are found in the gastrointestinal tract, lung, peritoneum, and gynecologic organs than just about any other type of breast cancer. Studies have also shown that metastatic signet ring cell carcinoma will have virtually the same immunohistochemical profile as the primary breast carcinoma.
But regardless of the site of origin of signet ring cell carcinoma (breast, colon, stomach) they are all highly prone to metastasize to the regional lymph nodes, (as well as the ovaries, lung, and peritoneal surfaces). Breast signet ring cell carcinomas do show a greater extent of axillary lymph node involvement than many other types of breast cancer. When they occur in the lymph nodes they tend to display a ‘sinus catarrh‘ pattern.
Histological features common to Signet ring cell breast carcinoma
The biologic hallmark of signet-ring cell breast carcinoma is mucin production. There are various different types of mucins (MUC1, MUC2, MUC3, etc.) and different combinations and strengths of mucins have been widely used to histologically differentiate between the various different types of adenocarcinomas. The nature of this mucin is basically acid mucosubstances consisting mainly of sialomucin with lesser amounts of sulphomucin.
Mucins produced due to the decreased production and thus immunoreactivity for E-cadherin occurs in about 75% of breast lobular carcinomas (with signet ring cells). Most breast signet ring cell carcinomas are positive for estrogen receptors, and negative for E-cadherin, and just about all cases will express MUC1.
Most signet ring cell breast carcinomas also express the CK7 protein. Unlike the other primary sites of signet ring cell carcinoma, breast signet ring cell carcinoma will tend to show intracytoplasmic lunima containing siolomucin, while the other types have more extended and ‘clear‘ cytoplasmic acid mucin.
Outlook for patients with signet ring cell carcinoma of the breast
Unfortunately, the prognosis for breast signet ring cell carcinoma is generally poorer than for other breast cancers. One of the reasons that is important to distinguish between mucinous breast carcinoma and signet ring cell breast carcinoma is because the latter is generally associated with a more aggressive clinical course, and ultimately a poorer prognosis.
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