C91.40Hairy cell leukemia not having achieved remission

C91.40 is the ICD-10-CM diagnosis code for Hairy cell leukemia not having achieved remission. It belongs to category C91 (lymphoid leukemia), block C81-C96 (malignant neoplasms of lymphoid, hematopoietic and related tissue) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within C91.4 (Hairy cell leukemia), C91.40 is specifically for Hairy cell leukemia not having achieved remission. Related codes cover in remission (C91.41) and in relapse (C91.42).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC, relative weight 5.6154), DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC, relative weight 4.381), DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC, relative weight 2.7307), DRG 820 (Lymphoma and Leukemia with Major O.R. Procedures with MCC, relative weight 6.2481), DRG 821 (Lymphoma and Leukemia with Major O.R. Procedures with CC, relative weight 2.2023), DRG 822 (Lymphoma and Leukemia with Major O.R. Procedures without CC/MCC, relative weight 1.1272) and 6 more, in Pre-MDC and MDC 17 (Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 202.40 (Leukemic reticuloendotheliosis, unspecified site, extranodal and solid organ sites).