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ICD-10 Code C91.9: Lymphoid leukemia, unspecified

C91.9 is an ICD-10 diagnosis entry used to group records related to Lymphoid leukemia, unspecified. You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen. ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Neoplasms (C00-D49).

What is this code?

ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Neoplasms (C00-D49).

When is it used?

  • May be used when a clinician documents lymphoid leukemia, unspecified in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
  • This entry may represent a broader category rather than the most specific billable code.

Code hierarchy

chapter
2Neoplasms (C00-D49)
block
C00-C96Malignant neoplasms
block
C81-C96Malignant neoplasms of lymphoid, hematopoietic and related tissue
category
C91Lymphoid leukemia
currentC91

Where you may see this code

You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.

Related specialists

OncologistGeneral Physician

Coding guidelines

Compatibility

Legacy code aligns to an official FY 2026 category. Frontend should resolve to the official category page and surface the billable child codes.
Legacy codes
C91.9
Replacement codes
C91.90 — Lymphoid leukemia, unspecified not having achieved remissionC91.91 — Lymphoid leukemia, unspecified, in remissionC91.92 — Lymphoid leukemia, unspecified, in relapse

Common synonyms

Lymphoid leukemia, unspecifiedLymphoid leukemia

Frequently asked questions

Code details

CodeC91.9
SystemICD10
Display nameLymphoid leukemia, unspecified
ChapterNeoplasms (C00-D49)
BlockMalignant neoplasms of lymphoid, hematopoietic and related tissue

Flags

BillableNo
Valid clinical useNo

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.