2026 ICD-10-CM Diagnosis Code C88.21Heavy chain disease, in remission

ICD-10-CM Codes›C00–D49›C81-C96›C88

ICD-10-CM C88.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C88.21 is a billable ICD-10-CM diagnosis code for heavy chain disease, in remission. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 820 through 825, 840 through 842. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Leukemia in remission.

Code Identity

ICD-10-CM Code
C88.21
Billable Status
Yes — Valid for Submission
Code Describes
Heavy chain disease, in remission
Short Description
Heavy chain disease, in remission
Same as the full description in the CMS dataset.
Parent Code
C88.2
Heavy chain disease

Code Classification

ChapterC00–D49Neoplasms
SectionC81-C96Malignant neoplasms of lymphoid, hematopoietic and related tissue
CategoryC88Malignant immunoproliferative diseases and certain other B-cell lymphomas
This CodeC88.21Heavy chain disease, in remission

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO075
Leukemia in remission
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Heavy Chain Disease

    a disorder of immunoglobulin synthesis in which large quantities of abnormal heavy chains are excreted in the urine. the amino acid sequences of the n-(amino-) terminal regions of these chains are normal, but they have a deletion extending from part of the variable domain through the first domain of the constant region, so that they cannot form cross-links to the light chains. the defect arises through faulty coupling of the variable (v) and constant (c) region genes.

  • Immunoproliferative Small Intestinal Disease

    a condition that is caused by hyperplasia of lymphocytes in the small intestine (intestine, small) and the mesenteric lymph nodes. these lymphocytes produce an anomalous alpha heavy chain protein. generally, these ipsid patients have either concurrent lymphoma or develop lymphoma within a few years. the disease was first described in the mediterranean region and is characterized by malabsorption; weight loss; diarrhea; and steatorrhea.

Code History & ChangesHistory

Replacement C88.21 replaces the following previously assigned code(s):

  • Z85.79 - Prsnl hx of malig neoplm of lymphoid, hematpoetc & rel tiss
FY 2025AddedAdded to the ICD-10-CM code setEffective October 1, 2024.
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C88.21Overview

Is C88.21 (Heavy chain disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report heavy chain disease, in remission on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C88.21 group to?

When heavy chain disease, in remission is the principal diagnosis on an inpatient stay, it groups to MS-DRG 820, 821, 822, 823, 824, 825, 840, 841, 842, with relative weights from 1.0104 to 5.8648 depending on complications. Higher weights mean higher Medicare reimbursement.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.