|poorly-differentiated carcinoma/cancer of unknown primary-- what is it?
May 17, 2001
What would positive keratin stains and negative S-100 stains indicate in cancer of unknown primary? Biopsy taken from left-neck lymph node.
All other tests did not reveal anything.
Response from Dr. Dezube
Cancer of unknown primary (CUP), a long name indeed. CUP basically means that you have been diagnosed with a cancer, yet no one know where it originated from. To help answer this question, pathologists do special stains on the tumor. Keratin and S-100 are commonly used stains. The fact that your tumor is keratin positive and S100 negative would indicate that the origin of your cancer is from epithelial cells. These cells are what make up the lung, the esophagus, the lining of the mouth, the gut, and many many other organs. (They however are quite distinct from the cells which make muscles). The left-neck location would suggest that your tumor arose somewhere in the neck or lung region, particularly if you have a history of tobacco use. Some providers would recommend that you have a bronchscopy and/or endoscopy to get a better idea.
Practically speaking, the keratin staining is important since these tumors respond quite well to platinum-based chemotherapy (agents such as cisplatin or carboplatin).
I wish you good luck. Will you be getting chemotherapy. Also I couldn't tell from your note whether you are HIV positive or not. BD.
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