Racemase

Racemase, also known as alpha-methylacyl-CoA racemase (AMACR) or P504S, is a protein produced by certain types of cells in the body. Pathologists use special tests to look for racemase in tissue samples because its presence or absence can help them make a diagnosis, particularly when examining conditions affecting the prostate gland. Although racemase is naturally produced by some normal cells, it is typically found in higher amounts in certain types of abnormal cells.

What types of cells normally express racemase?

In healthy individuals, racemase is typically expressed by specific cells in the liver, kidneys, and intestines, where it facilitates the processing of fatty acids. Normal prostate cells usually do not express racemase or express it at very low levels.

Why is racemase important in a pathology report?

Racemase is important because pathologists commonly use it as a marker to help identify prostate cancer cells. Cancerous prostate cells typically produce a large amount of racemase, while normal prostate cells produce little or none. For this reason, racemase is routinely tested alongside other markers, such as basal cell markers (p63 and high molecular weight cytokeratins), to confirm or rule out prostate cancer in tissue samples.

In addition to prostate cancer, racemase expression can sometimes be seen in other types of tumours, including cancers of the colon, breast, kidney, and liver. However, its most important use in pathology is in the diagnosis of prostate cancer.

How do pathologists test for racemase?

Pathologists use a laboratory technique called immunohistochemistry (IHC) to detect racemase in tissue samples. This test involves applying special antibodies to tissue samples taken during a biopsy or surgery. These antibodies specifically attach to racemase proteins in the cells. If racemase is present, the cells change colour, making them visible under the microscope.

How do pathologists interpret the results?

Pathologists look for brown or red staining inside the cells under the microscope to determine if racemase is present. The following are common ways pathologists interpret racemase staining:

• Positive result: Strong and widespread staining in prostate cells usually indicates malignant (cancerous) prostate tissue.

• Negative result: Little or no staining typically indicates benign (noncancerous) prostate tissue.

While racemase is very helpful, pathologists do not rely on it alone. They always interpret racemase staining together with other markers, clinical information, and the overall appearance of the tissue under the microscope to make an accurate diagnosis.

Questions to ask your doctor

• Was racemase found in my biopsy, and if so, what does this mean for my diagnosis?

• Were other markers tested in conjunction with racemase, and what were the results?

• Do I need further tests or treatment based on my pathology report?

• Should I have additional biopsies or regular follow-up based on these results?

• Are there any signs of cancer, and what are the next steps in my care?