Coding and coverage · ICD-10-CM

C91 › C91.1

C91.10 Chronic lymphocytic leukemia of B-cell type not having achieved remission

BillableCMS-HCC V28: HCC 22Chapter 2
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Instructional notes

Chapter 2

Notes
  • Functional activity
  • All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
  • Morphology [Histology]
  • Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
  • Primary malignant neoplasms overlapping site boundaries
  • A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
  • Malignant neoplasm of ectopic tissue
  • Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).

C91

Excludes1Not coded here: never report with this code, except when the two conditions are unrelated.
  • personal history of leukemia (Z85.6)

C91.1

Excludes1Not coded here: never report with this code, except when the two conditions are unrelated.
  • lymphoplasmacytic lymphoma (C83.0-)
Inclusion terms
  • Lymphoplasmacytic leukemia
  • Richter syndrome

This code

Inclusion terms
  • Chronic lymphocytic leukemia of B-cell type with failed remission
  • Chronic lymphocytic leukemia of B-cell type NOS

Chapter 2: Neoplasms · C00-C96 Malignant neoplasms (C00-C96)

Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.

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