SOX11: Definition

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SOX11 is a protein that works inside the nucleus of a cell to switch other genes on and off. Pathologists test for SOX11 mainly to help diagnose mantle cell lymphoma, a type of lymphoma made of small B cells. SOX11 is especially helpful in the small number of mantle cell lymphomas that do not show the usual marker, cyclin D1.

This article explains what SOX11 is, how pathologists use it to diagnose mantle cell lymphoma and other tumors, and what a SOX11 result in your pathology report means.

What is SOX11?

SOX11 is a protein that controls which genes are active in a cell, a type of protein called a transcription factor. It plays an important role before birth, helping the brain, nerves, and skeleton develop. Most mature cells in the adult body, including normal lymphocytes, do not make SOX11. This is why finding SOX11 in a group of lymphocytes is unusual and can point toward a specific type of lymphoma.

How do pathologists test for SOX11?

Pathologists test for SOX11 using immunohistochemistry, which uses antibodies to detect specific proteins in a thin slice of tissue. Cells that make SOX11 show a brown color inside the nucleus under the microscope. Normal lymphocytes in the same sample stay unstained, which helps the pathologist see whether the abnormal cells are positive.

How does SOX11 help diagnose mantle cell lymphoma?

SOX11 helps diagnose mantle cell lymphoma because, in most cases, the cancer cells express SOX11, while most other small B-cell lymphomas do not. The pathologist usually looks at SOX11 together with CD5, CD23, and cyclin D1. Typical patterns include:

Mantle cell lymphoma. The cells are usually positive for CD5, cyclin D1, and SOX11 and negative for CD23.
Cyclin D1-negative mantle cell lymphoma. A small number of mantle cell lymphomas lack cyclin D1, and in these cases a positive SOX11 result is one of the most useful clues to the diagnosis.
Chronic lymphocytic leukemia and small lymphocytic lymphoma. The cells are usually positive for CD5 and CD23 but negative for both cyclin D1 and SOX11.
Other small B-cell lymphomas. Follicular lymphoma and marginal zone lymphoma are usually negative for SOX11.

Can mantle cell lymphoma be negative for SOX11?

Mantle cell lymphoma can be negative for SOX11 in one specific form. This form, called leukemic non-nodal mantle cell lymphoma, mainly involves the blood, bone marrow, and spleen rather than the lymph nodes. It often grows more slowly than typical mantle cell lymphoma. If your report describes a SOX11-negative mantle cell lymphoma, your doctor can explain whether this form applies to you.

Where else might SOX11 be positive?

SOX11 can also be positive in a few other blood cancers and some solid tumors, so the pathologist always interprets it alongside other markers. Examples include:

Other blood cancers. Some cases of Burkitt lymphoma and lymphoblastic lymphoma are positive for SOX11.
Childhood tumors. Several tumors that arise from developing nerve and brain cells, such as neuroblastoma and medulloblastoma, often make SOX11.
Pancreas tumors. Almost all cases of solid pseudopapillary neoplasm, an uncommon tumor of the pancreas, are positive for SOX11.

What does a SOX11 result mean in my report?

A SOX11 result in your report describes whether the abnormal cells make this protein. Your report may describe the result in one of a few ways:

Positive. The abnormal cells make SOX11, which supports a diagnosis of mantle cell lymphoma when the cells are small B cells and the other markers fit.
Negative. The abnormal cells do not make SOX11, which points toward a different small B-cell lymphoma or, rarely, the leukemic non-nodal form of mantle cell lymphoma.

Questions to ask your doctor

Were the abnormal cells in my sample positive or negative for SOX11?
Were they also positive for cyclin D1?
Which other markers did the pathologist test along with SOX11?
Do I have mantle cell lymphoma or a different type of lymphoma?
If my lymphoma is SOX11-negative, does that change what it means for me?
Will I need genetic tests or a bone marrow biopsy?