CD 34 is a tumor marker used for –
## **Core Concept**
CD34 is a transmembrane phosphoglycoprotein expressed on early lymphoid and myeloid cells, endothelial progenitor cells, and hematopoietic progenitor cells. It serves as a marker for identifying and isolating these cells. In the context of tumor markers, CD34 is particularly relevant for certain types of vascular tumors and hematological malignancies.
## **Why the Correct Answer is Right**
CD34 is notably used as a tumor marker for **vascular tumors**, such as **Kaposi's sarcoma** and **hemangiopericytoma**. Kaposi's sarcoma is a type of cancer that forms in the lining of blood and lymph vessels and is known to express CD34. This marker helps in the diagnosis and characterization of these tumors.
## **Why Each Wrong Option is Incorrect**
- **Option A:** Not specified, but if considering common tumor markers like CEA (Carcinoembryonic antigen) or CA-125, these are not related to CD34.
- **Option B:** Similarly, not specified, but if thinking of markers like PSA (Prostate-Specific Antigen) or AFP (Alpha-fetoprotein), these are unrelated to CD34.
- **Option C:** This option might relate to specific types of sarcomas or carcinomas, but without specification, it's hard to directly refute. However, CD34's specificity to vascular tumors or hematopoietic malignancies makes other tumor types less likely.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **CD34** is crucial in the diagnosis of **Kaposi's sarcoma**, a tumor that can occur in immunocompromised patients, such as those with HIV/AIDS. The expression of CD34 in this context supports its vascular origin.
## **Correct Answer:** D. Kaposi's sarcoma.