To differenciate the origin of the tumor , immunohistochemistry of the tumor can be usefull:

tumor from thyroid specificaly express nuclear transcription factor TTF1 and thyroglobulin,

tumor from mammary gland can express hormonal receptors against estrogens and progesteron and erB2(HER1)

for salivary gland tumors, it is more delicate and very polymorphous.

So the precedent immunostains can exclude salivary origin

SE

Yes, I would support Sandrine idea. IHC is the way to distinguish tumor origin. I don't know specific markers for each tumor but you can easily find it in literature or in pathology books. Pay attention to buy the correct Ab for IHC application and to set up a proper protocol for the IHC. If you are familiar with this technique you should not have any problem.

Good luck

I think that best salivary gland tumours are represented by large spectrum cytokeratins, epithelial membrane antigen, lysozime , lactoferrin and alpha-1-antitrypsin/chymotrypsin for those derived from ductal cells; alternatively, smooth muscle actin, S-100 protein, fibronectin and GFAP for those constitued by myoepithelial cells. Of course, by immunohistochemical procedures....there a lot of protocols. Best regards, Giovanni Tuccari

To determine the origin of cancer cells in metastasis or secondary tumor sites, anatomo-pathologists used cytokeratin IHC for the breast epithelial cancer cells (cytokeratin 19 for example and others).

But development of mammary gland tumor in the mice neck is not usual !

I agree with Isabella. Mice can develop tumors in neck area, which may actually be mammary gland tumor. The anatomical location of mice breast is such that it appears a tumor in the neck but it is in one of the uppermost breast. Mice had 5 pairs of breast 3 in the upper and 2 in the lower region. The uppermost is actually wrapped around the neck. By dissection, it is easy to see the tumor in the breast. I can send you some pictures.

Good replies but, to recap, the best approach I would use should I face this problem, and I do very often, is to sit down with the pathologist(s) and look at the tumor morphology first, I'm not a MD, and usually I got the right tips from the pathologists as to what to use. Davide is right, look for the best and, IHC-tested, Abs to see what you get in your hands. Sometimes the Hospital Lab runs those Abs and you don't need to invent the wheel. IHC is a "voodoo" science if it's not approached correctly.

In addition to the markers listed in earlier discussions, staining for markers of myoepithelial cells like the S100A2 and osteonectin may further confirm mammary origin of the tumor. I agree, it is absolutely essential to test the validity of the assay with negative and postive controls before concluding anything.

Pamela: Only about 70% of breast tumors are +; so this will not fly because some tumors may be ER/PR negative.

What about morphology? See "International Classification of Rodent Tumors - The Mouse", Editor Ulrich Mohr, Springer-Verlag, WHO International Agency for Research on Cancer, ISBN 3-540-64578-0

Our lab isolated organ-specific adult stem cells in 1987 and since then, all of our normal adult organ-specific stem cells expressed Oct4A, as did the "cancer stem cells". We feel that Oct4A is a "universal" stem cell marker. Moreover, we noticed that there seemed to be organ-specific markers associated or co-expressed with the Oct4A, such as estrogen-receptor with our human adult breast stem cells or albumin with our human liver stem cells. We also noticed that the human adult stem cells did not have functional gap junctional intercellular communication. [ see Tai, M.-H. et al, Carcinogenesis 20: 485-502, 2005.]

I think at first, accurate observation and physical examination must be done. These will help to finding tumor's origin. After that, starting next steps like radio-graphic or pathological methods can be useful.

I think mucin could be a honest marker for breast tumor

Besides CK19, mammoglobin is a fairly well accepted breast biomarker.