Here is an overview of the key biomarkers used in the diagnosis of different types of sarcoma:
1. SS18-SSX Fusion Protein
- Sarcoma Type: Synovial Sarcoma
- Description: This fusion protein results from a translocation between chromosomes 18 and X, creating the SS18-SSX fusion gene. It is a specific marker for synovial sarcoma and is detected through molecular testing. This genetic mutation is critical for confirming the diagnosis of synovial sarcoma.
2. TLE1 (Transducin-like Enhancer of Split 1)
- Sarcoma Type: Synovial Sarcoma
- Description: TLE1 is an immunohistochemical marker highly expressed in synovial sarcomas. It is commonly used in conjunction with other markers such as the SS18-SSX fusion protein to strengthen diagnostic accuracy.
3. EMA (Epithelial Membrane Antigen)
- Sarcoma Type: Synovial Sarcoma, Epithelioid Sarcoma
- Description: EMA is a glycoprotein found on the surface of epithelial cells. It is used to differentiate sarcomas with epithelial-like characteristics from other mesenchymal tumors, making it valuable in diagnosing epithelioid and synovial sarcomas.
4. CD34
- Sarcoma Type: Angiosarcoma, Dermatofibrosarcoma Protuberans (DFSP)
- Description: CD34 is a marker found on the surface of endothelial cells and hematopoietic stem cells. It is commonly used in the diagnosis of vascular sarcomas like angiosarcoma and soft tissue sarcomas like DFSP.
5. S100
- Sarcoma Type: Malignant Peripheral Nerve Sheath Tumour (MPNST), Clear Cell Sarcoma
- Description: S100 is a protein expressed in tumours of neural and melanocytic origin. It is a key marker for diagnosing MPNST and clear cell sarcomas, which are sarcomas of melanocytic origin.
6. SOX10
- Sarcoma Type: Malignant Peripheral Nerve Sheath Tumour (MPNST), Clear Cell Sarcoma
- Description: SOX10 is another marker used in conjunction with S100 to diagnose sarcomas of neural origin. It is especially useful in identifying MPNST and clear cell sarcoma.
7. CD31
- Sarcoma Type: Angiosarcoma
- Description: CD31 is a vascular endothelial marker used to confirm the diagnosis of angiosarcoma. It helps differentiate vascular tumours from other types of sarcoma.
8. Desmin
- Sarcoma Type: Rhabdomyosarcoma, Leiomyosarcoma
- Description: Desmin is a muscle-specific protein used as a marker to diagnose sarcomas that arise from muscle tissue, such as rhabdomyosarcoma and leiomyosarcoma.
9. Myogenin and MyoD1
- Sarcoma Type: Rhabdomyosarcoma
- Description: Myogenin and MyoD1 are transcription factors critical in muscle differentiation. They are used to confirm the diagnosis of rhabdomyosarcoma, a type of sarcoma that arises in skeletal muscle.
10. HMB-45 and Melan-A
- Sarcoma Type: Clear Cell Sarcoma
- Description: These markers are associated with melanocytic tumors and are often used to diagnose clear cell sarcoma, a type of sarcoma that shares similarities with melanoma.
11. Cytokeratins
- Sarcoma Type: Epithelioid Sarcoma, Synovial Sarcoma
- Description: Cytokeratins are intermediate filament proteins found in epithelial cells. Their expression in certain sarcomas like epithelioid and synovial sarcomas aids in diagnosis by indicating epithelial differentiation.
12. ALK (Anaplastic Lymphoma Kinase)
- Sarcoma Type: Inflammatory Myofibroblastic Tumour (IMT)
- Description: ALK is a tyrosine kinase receptor involved in cell growth. Mutations in the ALK gene are commonly found in IMT, making it an important biomarker for this type of sarcoma.
13. EWSR1 Gene Translocation
- Sarcoma Type: Ewing Sarcoma
- Description: The EWSR1 gene translocation, typically involving FLI1, is a defining genetic mutation in Ewing sarcoma. It is used as a molecular marker to confirm the diagnosis of this aggressive bone and soft tissue cancer.
14. MDM2 Amplification
- Sarcoma Type: Liposarcoma (Well-differentiated and Dedifferentiated)
- Description: MDM2 is a gene that regulates the tumour suppressor p53. Amplification of MDM2 is commonly seen in liposarcomas and helps distinguish well-differentiated liposarcoma from benign lipomas.
15. p16 (CDKN2A)
- Sarcoma Type: Malignant Peripheral Nerve Sheath Tumour (MPNST)
- Description: p16 is a tumour suppressor gene, and its loss is frequently observed in MPNSTs. This marker helps differentiate MPNST from benign nerve sheath tumors.
16. FUS-CHOP Fusion Protein
- Sarcoma Type: Myxoid Liposarcoma
- Description: This fusion protein results from a translocation between chromosomes 12 and 16, leading to the formation of the FUS-CHOP gene, which is characteristic of myxoid liposarcoma.
17. DICER1 Mutation
- Sarcoma Type: Pleuropulmonary Blastoma
- Description: Mutations in the DICER1 gene are commonly found in pleuropulmonary blastoma, a rare childhood sarcoma. This genetic mutation is critical for diagnosis.
18. WT1 (Wilms Tumor 1)
- Sarcoma Type: Desmoplastic Small Round Cell Tumour (DSRCT)
- Description: WT1 is a transcription factor whose expression is altered in DSRCT. It is often used in combination with other markers to confirm the diagnosis.
These biomarkers play an essential role in diagnosing, classifying, and developing treatment strategies for different types of sarcomas. Each marker helps pathologists and oncologists identify the specific characteristics of the tumour, enabling personalised treatment plans.