Related Conditions & Considerations

An accurate diagnosis is essential to ensure appropriate care. Several lymphoid diseases share features with chronic lymphocytic leukemia (CLL) but differ in important ways, including how they behave and how they are treated.

Hairy Cell Leukemia (HCL)

Hairy cell leukemia is a rare blood cancer named for the “hair-like” projections seen on the surface of the cells under a microscope.

Many patients have an enlarged spleen and may have few or no abnormal cells in the bloodstream. HCL most often affects middle-aged or older adults and is more common in men.

While distinct from CLL, HCL is highly treatable, often with therapies such as nucleoside analogs and monoclonal antibodies (e.g., rituximab).

Richter’s Transformation

Richter’s transformation occurs when CLL changes into a more aggressive form of lymphoma, most commonly diffuse large B-cell lymphoma.

This transformation is uncommon, occurring in approximately 5–10% of patients, but requires different and more intensive treatment approaches similar to those used for aggressive lymphomas. Research is ongoing to better understand why this occurs.

Lymphomas

Lymphoma is another type of cancer that affects the immune system. Unlike leukemia, which begins in the bone marrow and circulates in the blood, lymphoma primarily involves lymph nodes and other lymphoid tissues.

In some cases, lymphoma cells can enter the bloodstream and resemble leukemia. This can occur in diseases such as mantle cell lymphoma and marginal zone lymphoma, and less commonly in follicular lymphoma. Treatment varies depending on the specific diagnosis.

Small Lymphocytic Lymphoma (SLL)

Small lymphocytic lymphoma (SLL) is biologically the same disease as CLL. The difference lies in where the cancer cells are found:

• CLL: Primarily in the blood and bone marrow
• SLL: Primarily in the lymph nodes and lymphoid tissues

Prognosis and treatment approaches for CLL and SLL are the same.

Waldenström Macroglobulinemia

This is a rare B-cell disorder in which cancer cells produce abnormal antibodies. These proteins can lead to a range of symptoms, including fatigue and circulation-related issues.

Treatment often includes targeted therapies and monoclonal antibodies, such as rituximab.

Monoclonal B-Cell Lymphocytosis (MBL)

Some individuals have small populations of CLL-like cells in their blood without having leukemia. This condition is called monoclonal B-cell lymphocytosis (MBL).

MBL typically does not require treatment, and the risk of progressing to CLL is low (approximately 1% per year).

Finding the Right Expert

Because these conditions can be complex and sometimes difficult to distinguish, evaluation by experienced specialists is important. Hematologists, oncologists, and pathologists with expertise in lymphoid diseases can help ensure an accurate diagnosis.

In some cases, seeking a second opinion—particularly at a center with experience in CLL and related disorders—can be valuable. An accurate diagnosis and appropriate treatment plan are especially important when making initial treatment decisions.