D2-40

D2-40 is a protein normally found in the cells lining the lymphatic vessels, which are part of the body’s immune system. These vessels help drain fluid from tissues and transport immune cells. This protein can also be found in other types of cells, allowing pathologists to identify specific tumours made up of these cells.

What types of normal cells and tissues express D2-40?

D2-40 is typically found in:

• Lymphatic endothelial cells (cells that line the lymphatic vessels).
• Adrenal cortical cells (cells from the outer layer of the adrenal glands).
• Myoepithelial cells of the breast (specialized cells in the breast that help move milk through ducts).
• Follicular dendritic cells (immune system cells that help trap and display foreign particles).
• Granulosa cells (cells found in the ovaries that support egg development).
• Mesothelial cells (cells that line the outer surface of organs).
• Basal cells of the skin and squamous mucosal epithelium (cells that form the protective outer layers of the skin and certain mucosal surfaces).

What types of benign (noncancerous) tumours express D2-40?

Some benign tumours that may show D2-40 expression include:

• Dermatofibroma (a common skin growth).
• Odontogenic tumours (tumours that develop in the jaw from tooth-forming tissues).
• Myoepithelial tumours (tumours that arise from myoepithelial cells, which are found in sweat glands and the breast).
• Hemangiomas and lymphatic malformations (vascular growths involving blood or lymphatic vessels).

What types of malignant (cancerous) tumours express D2-40?

Many types of cancers express D2-40, including:

• Angiosarcoma and Kaposi sarcoma (cancers of the blood and lymphatic vessels).
• Malignant mesothelioma (a cancer of the lining of the lungs, abdomen, or heart).
• Follicular dendritic cell tumour (a rare tumour of the immune system).
• Squamous cell carcinoma (a common type of skin and mucosal cancer).
• Germ cell tumours, including seminomas and some embryonal carcinomas.
• Serous carcinoma (a type of ovarian and endometrial cancer).
• Pleomorphic carcinoma of the lung.
• Adrenocortical carcinoma (a rare cancer of the adrenal glands).

Why do pathologists test for D2-40?

Pathologists use D2-40 to help diagnose different types of tumours and distinguish between them. One of its most important uses is identifying lymphatic vessels to determine if cancer cells are inside them. Detecting lymphatic invasion is critical to cancer staging and helps guide treatment decisions.

How do pathologists test for D2-40?

Pathologists test for D2-40 using a technique called immunohistochemistry. In this test, a special dye attaches to D2-40 in a tissue sample, allowing doctors to see where the protein is present. Testing for D2-40 is particularly useful in identifying lymphatic vessels, which can help determine whether cancer cells have spread into them (lymphatic invasion). This information is crucial for making an accurate diagnosis and planning the best treatment. Testing for D2-40 also helps pathologists identify certain types of benign (noncancerous) and malignant (cancerous) tumours.