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ICD-10-CM C91.61: Prolymphocytic leukemia of T-cell type, in remission

C91.61 is the billable ICD-10-CM code for prolymphocytic leukemia of T-cell type, in remission, in category C91 (Lymphoid leukemia) of the Malignant neoplasms of lymphoid, hematopoietic and related tissue section. As a principal diagnosis it groups to MS-DRG 820 Lymphoma and Leukemia with Major O.R. Procedures with MCC, MS-DRG 821 Lymphoma and Leukemia with Major O.R. Procedures with CC, MS-DRG 822 Lymphoma and Leukemia with Major O.R. Procedures without CC/MCC (MDC 17 MDC 17: Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms). It maps to HCC 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers) in CMS-HCC V28. As a secondary diagnosis it is a CC, excluded with 113 principal diagnoses. 23 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
C91.61
billable FY2027 ICD-10-CM code
Category
C91 Lymphoid leukemia
Chapter
2: Neoplasms (C00-D49)
CC/MCC (MS-DRG v44)
CC
CMS-HCC V28
HCC 19
POA reporting
Required

Tabular list notes for C91.61

The tabular list has no notes on C91.61 itself; the notes below apply from its parent headings.

Inherited from C91 (Lymphoid leukemia)

Excludes1 (never coded together)
  • personal history of leukemia (Z85.6)

MS-DRG grouping when C91.61 is the principal diagnosis

MS-DRG v44 groups for C91.61 as principal diagnosis
MDCMS-DRGs
17 MDC 17: Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms820821822823824825840841842

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for C91.61 shows the full grouping logic.

CC/MCC status and inpatient edits

As a secondary diagnosis, C91.61 is a CC under MS-DRG v44, unless the principal diagnosis is one of the 113 codes in its exclusion list. Check C91.61 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.

CMS-HCC V28 risk adjustment

In the PY2027 mapping, C91.61 maps to HCC 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers). The HCC lookup shows the RAF weight and the hierarchy.

LCD billing and coding articles that list C91.61

23 current Medicare billing and coding articles list C91.61 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM C91.61 mean?

C91.61 means prolymphocytic leukemia of T-cell type, in remission. It is one of 25 billable codes under C91, lymphoid leukemia.

Which MS-DRG does C91.61 group to?

As the principal diagnosis, C91.61 groups to MS-DRG 820 Lymphoma and Leukemia with Major O.R. Procedures with MCC, MS-DRG 821 Lymphoma and Leukemia with Major O.R. Procedures with CC, MS-DRG 822 Lymphoma and Leukemia with Major O.R. Procedures without CC/MCC (MDC 17 MDC 17: Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Does C91.61 map to an HCC?

Yes: HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers, in the PY2027 CMS-HCC V28 mapping.

Is C91.61 a CC or MCC?

C91.61 is a CC under MS-DRG v44; 113 principal diagnoses exclude it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.