C91.4
⚠ Non-billable (Header)Hairy cell leukemia
Neoplasms (C00-D49)
⚠️ This is a category header code — not billable. Use a more specific child code below.
Also Known As
❌ Excludes1
inheritedRules inherited from parent codes in the hierarchy.
- • personal history of leukemia (Z85.6)
Child Codes (3)
Clinical Description
ICD-10-CM code C91.4 represents hairy cell leukemia. This code falls under the Neoplasms (C00-D49) classification. It is a non-billable category header code. A more specific child code from the list below must be used for billing and reimbursement purposes.
This is a 5-character code at the 4th level of specificity. There are 3 more specific child codes under C91.4. Coders should note that C91.4 has 1 Excludes1 restriction(s) — codes that cannot be reported together on the same claim.
Frequently Asked Questions
What is ICD-10 code C91.4?
ICD-10-CM code C91.4 is "Hairy cell leukemia". It belongs to the category: Neoplasms (C00-D49).
Is C91.4 a billable ICD-10 code?
No, C91.4 is a non-billable header code. A more specific child code must be used for billing.
What codes are excluded with C91.4?
C91.4 has 1 Excludes1 rule(s). These codes are mutually exclusive and cannot be coded together on the same claim.
Related Codes in C91
Other codes in the same category that may be relevant for differential coding:
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Data Source
CMS ICD-10-CM 2026 Tabular List
Updated October 1, 2025 (FY2026)