2026 ICD-10-CM Diagnosis Code C90.21Extramedullary plasmacytoma in remission

ICD-10-CM Codes›C00–D49›C81-C96›C90

ICD-10-CM C90.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C90.21 is a billable ICD-10-CM diagnosis code for extramedullary plasmacytoma 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. Coders also document this condition as extramedullary plasmacytoma. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myeloma in remission.

Code Identity

ICD-10-CM Code
C90.21
Billable Status
Yes — Valid for Submission
Code Describes
Extramedullary plasmacytoma in remission
Short Description
Extramedullary plasmacytoma in remission
Same as the full description in the CMS dataset.
Parent Code
C90.2
Extramedullary plasmacytoma

Code Classification

ChapterC00–D49Neoplasms
SectionC81-C96Malignant neoplasms of lymphoid, hematopoietic and related tissue
CategoryC90Multiple myeloma and malignant plasma cell neoplasms
This CodeC90.21Extramedullary plasmacytoma in remission

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Extramedullary plasmacytoma
  • Extramedullary plasmacytoma in remission
  • Immunoproliferative neoplasm in remission
  • Plasmacytoma
  • Plasmacytoma in remission

Clinical ClassificationClinical

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

CCSR NEO078
Myeloma in remission
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Interleukin-6

    a cytokine that stimulates the growth and differentiation of b-lymphocytes and is also a growth factor for hybridomas and plasmacytomas. it is produced by many different cells including t-lymphocytes; monocytes; and fibroblasts.

  • Plasmacytoma

    any discrete, presumably solitary, mass of neoplastic plasma cells either in bone marrow or various extramedullary sites.

Patient EducationClinical

Multiple Myeloma

Multiple myeloma is a cancer that begins in plasma cells, a type of white blood cell. These cells are part of your immune system, which helps protect the body from germs and other harmful substances. In time, myeloma cells collect in the bone marrow and in the solid parts of bones.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C90.21 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
203.81 Oth imnprfl npl w rmsn
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C90.21Overview

Is C90.21 (Extramedullary plasmacytoma) a billable code?

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

What MS-DRG does C90.21 group to?

When extramedullary plasmacytoma 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.

What is the ICD-9 equivalent of C90.21?

Under the General Equivalence Mappings, extramedullary plasmacytoma in remission converts to ICD-9-CM 203.81 (oth imnprfl npl w rmsn). The mapping is approximate, so confirm the match fits the documentation.

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.