2026 ICD-10-CM Diagnosis Code C91.10Chronic lymphocytic leukemia of B-cell type not having achieved remission
ICD-10-CM Codes›C00–D49›C81-C96›C91
- Billable — Valid for Submission
- Chronic Condition
C91.10 is a billable ICD-10-CM diagnosis code for chronic lymphocytic leukemia of B-cell type not having achieved remission. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 820 through 825, 840 through 842. Coders also document this condition as b-cell chronic lymphocytic leukemia variant. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Leukemia - chronic lymphocytic leukemia (CLL).
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- B-cell chronic lymphocytic leukemia variant
- Chronic lymphocytic prolymphocytic leukemia syndrome
- Prolymphocytic leukemia
- Richter's syndrome
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Chronic lymphocytic leukemia of B-cell type with failed remission
- Chronic lymphocytic leukemia of B-cell type NOS
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Chronic Lymphocytic Leukemia
Leukemia is a term for cancers of the blood cells. Leukemia starts in blood-forming tissues such as the bone marrow. Your bone marrow makes the cells which will develop into white blood cells, red blood cells, and platelets. Each type of cell has a different job:
The full article covers:
- What is leukemia?
- What is chronic lymphocytic leukemia (CLL)?
- What causes chronic lymphocytic leukemia (CLL)?
- Who is at risk for chronic lymphocytic leukemia (CLL)?
- What are the symptoms of chronic lymphocytic leukemia (CLL)?
- How is chronic lymphocytic leukemia (CLL) diagnosed?
- What are the treatments for chronic lymphocytic leukemia (CLL)?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C91.10 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C91.10Overview
Is C91.10 (Chronic lymphocytic leukemia of B-cell type) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report chronic lymphocytic leukemia of B-cell type not having achieved remission on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C91.10 group to?
When chronic lymphocytic leukemia of B-cell type not having achieved remission is the principal diagnosis on an inpatient stay, it groups to MS-DRG 820, 821, 822, 823, 824, 825, 840, 841, 842, with relative weights from 1.0104 to 5.8648 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of C91.10?
Under the General Equivalence Mappings, chronic lymphocytic leukemia of B-cell type not having achieved remission converts to ICD-9-CM 204.10 (ch lym leuk wo achv rmsn). The mapping is a direct match.
Footnotes
[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:
- The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
- The condition places limitations on self-care, independent living, and social interactions.
