• S-100, a protein found in neuroectodermal tissues, is useful in the diagnosis of melanomas or nerve tumors.
• Neuron-specific enolase is positive in small cell (oat cell) lung cancer.
• Leukocyte-common antigen found on the surface of leukocytes is positive in leukemia and lymphoma.
• Prostate-specific antigen (PSA) is positive in prostate cancer.
• Human chorionic gonadotropin is often positive in germ cell tumors such as testis cancer and in
choriocarcinoma .
• Alpha-fetoprotein is present in primary liver cancer and certain germ cell tumors.
• Estrogen receptors are present in breast cancer and cancer of the lining of the uterus (endometrial cancer).
Finding estrogen receptors not only helps in the diagnosis but suggests that hormonal therapy may be useful.
Many new tissue stains are being developed and are rapidly enlarging the diagnostic capability of the modern pathologist .
Electron Microscopy (EM) Regular microscopes magnify tissues up to 1,000 times. The electron microscope can magnify tissues 50,000 to 100,000 times. Very small structures inside and on the surfaces of cells , often characteristic of certain types of cancer cells, can be seen. There are structures characteristic of squamous cell cancers, cancers of neuroendocrine origin, muscle tumors and most melanomas. Besides suggesting likely sites, EM studies are useful in eliminating certain tumor types.
