The Conundrum of CLL & SLL Claims – Chronic Lymphocytic Leukemia & Small Lymphocytic Lymphoma

Chronic Lymphocytic Leukemia is one of the most common forms of leukemia. It is an indolent form of leukemia, which may exist for many years without change or impact on a person, and then quickly evolve into other forms of more aggressive Leukemia(s) or Lymphoma(s).

As it relates to EEOICPA and claim adjudication, claims for CLL can be won based on significant exposure to benzene under Part E, causation due to chemical exposure. This is based on a worker’s job function/labor category, during any time period, as long as there is substantive evidence of the potential for significant exposure to benzene or chemicals with benzene as an ingredient.

By contrast, under Part B, causation due to radiation exposure, claims for CLL rarely meet the causation threshold through Dose Reconstruction and are seldom approved. Wait, aren’t CLL & SLL the same disease? Yes. And No. It depends. However, if the same condition is referred to as SLL, Small Lymphocytic Lymphoma, then based on a worker’s qualifying employment, the guidelines of Special Exposure Cohort may come into effect. 

So, how does one recast CLL as SLL, or CLL/SLL? Well, the starting point is already in your medical file and diagnosis. First some background … and at the end a solution.

EEOICPA was written by Congress in 2000, and at that time CLL was considered a form of Leukemia, and medical science at that time characterized it as non-radiogenic. In other words, CLL was more likely caused by factors such as genetics and lifestyle, and not necessarily due to exposure to radiation sources. Further, the language of EEOICPA was modeled after medical conditions explicitly found in the original Radiation Exposure Compensation Act (RECA), based on science from Hiroshima and Nagasaki.

For the longest time, the method for biopsy/pathology analysis for CLL was venipuncture (a blood draw). For SLL, a lymph node tissue biopsy was the primary source for pathological analysis. Well, modern day science now demonstrates they are in fact the same condition, just historically arrived at through different techniques. Whether a medical provider calls the condition CLL, SLL or CLL/SLL, the treatment approaches are most often precisely the same. And most Hematologists prefer and recommend non-invasive approaches for biopsy … hence, a decline in surgical biopsies and increased reliance on phlebotomy (venipuncture). 

With that, CMS Medicare coding guidelines for reimbursement of services to insurance companies decided to collapse the ICD 10 code(s) into one common code for billing purposes. This is where you follow the money and funding. ICD 10 code for CLL is C91.10, for SLL is C83.0, and for billing purposes, and most every medical provider billing system shows C91.10 with a description of CLL/SLL.

This is where I add the caveat that I am not a medical professional, medical historian, CMS/Medicare Billing expert, and so on. I am not providing references and links to articles. I have done the research. I have spent 15 years trying to understand how we got here, and how to solve this great conundrum for my clients!

More context …

What we have in 2026 are three different Federal agencies classifying the condition of CLL/SLL under different schemes and for different purposes. 

1. As stated above, for CMS billing/treatment suite purposes, billing systems uses the ICD 10 classification of C91.10 to align with accepted, standardized, treatment suites (CPT codes/services). C91.10 is commonly and historically based on the method of biopsy, blood draws, to establish diagnosis.
2. The ICD 10 for SLL is C83.00, and more commonly (and historically) applied (past tense) to tissue-based diagnoses, sampled tissue, or lymph node biopsies. Historically, this diagnosis required an invasive, surgical procedure, which has recently been minimized as technology has shown that blood draw with appropriate analysis arrives at the same diagnosis.
3. The Center of Disease Control/SEER system of classification and tracking was updated 10+ years ago to reclassify all instances of CLL or SLL to be a form of B Cell Lymphoma, NOT a form of Leukemia.
4. The EEOICPA Program was written by Congress in 2000, and at that time CLL was considered a form of Leukemia, and distinctly different condition than SLL, a form of B Cell Lymphoma. 
5. Further, and to the main point, under EEOICPA, forms of Non-Hodgkins Lymphoma are eligible for consideration for “presumptive causation”, where Special Exposure Cohorts apply to certain work sites, due to radiation exposure, and immediate approval for medical coverage for workers under the program. Claimants are in a much-preferred position for benefits approval with a diagnosis of SLL, a Non-Hodgkins Lymphoma.

To be clear, I am not suggesting any change in how any medical provider treats, manages, or bills for services related to a CLL/SLL condition. I am stating that such condition(s) which is characterized currently as CLL or CLL/SLL, also carries a dual diagnosis of both CLL (C91.10) and SLL (83.00). This is no different than having COPD, but more specifically Chronic Bronchitis or Emphysema, both of which are classified for billing purposes as COPD.

For purposes of pursuing claims under EEOICPA where there is a diagnosis of CLL or CLL/SLL, my strongest suggestion is to share the information above with your medical provider and request that they document in a letter or in the medical record that you carry a dual diagnosis of both CLL (C91.10) and SLL (83.00). When filing a new claim, reference both CLL and SLL on separate lines of a claim form. Provide a letter/statement from the doctor affirming the dual diagnoses.

Notes: 

Something to watch for with these forms of Leukemias and Lymphomas is they can evolve/transform over time. ICD coding by the medical provider can change as well for billings purposes. And, at times, a claimant under EEOICPA must file to add as a consequential condition to new condition.

For CLL, if there is evidence of “Richters Transformation” to an alternate form of Lymphoma, or any other type of Lymphoma, this needs to be addressed and past claims that were denied can be refiled.

To be transparent, these unnecessary distinctions in classifications have been brought to the highest levels of EEOICPA management to highlight how out of touch the language and definitions from 2000 are with current science. However, the agency itself cannot change what Congress drafted, nor critique how they arrived at the set of cancers which conform to policy. So, we are left with how to adapt medical diagnoses, within ethical reason, to work within the program parameters.