2026 ICD-10-CM Diagnosis Code C96.0Multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis
ICD-10-CM Codes›C00–D49›C81-C96›C96
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 21
- Chronic Condition
C96.0 is a billable ICD-10-CM diagnosis code for multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 11 through 13, 826 through 830, 843 through 845. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 47 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Non-Hodgkin lymphoma.
For Medicare Advantage risk adjustment, C96.0 maps to CMS-HCC Category 21 (Lymphoma and Other Cancers) under the V28 model, adding a risk factor of about 0.671 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C96.0 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Disseminated Langerhans cell histiocytosis of abdominal lymph nodes
- Disseminated Langerhans cell histiocytosis of bone
- Disseminated Langerhans cell histiocytosis of cervical lymph nodes
- Disseminated Langerhans cell histiocytosis of lymph nodes of head
- Disseminated Langerhans cell histiocytosis of lymph nodes of lower limb
- Disseminated Langerhans cell histiocytosis of lymph nodes of multiple sites
- Disseminated Langerhans cell histiocytosis of lymph nodes of thorax
- Disseminated Langerhans cell histiocytosis of lymph nodes of upper limb
- Disseminated Langerhans cell histiocytosis of pelvic lymph nodes
- Disseminated Langerhans cell histiocytosis of spleen
- Langerhans cell histiocytosis, disseminated
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Histiocytosis X, multisystemic
- Letterer-Siwe disease
Type 1 Excludes
- adult pulmonary Langerhans cell histiocytosis J84.82
- multifocal and unisystemic Langerhans-cell histiocytosis C96.5
- unifocal Langerhans-cell histiocytosis C96.6
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Letterer-Siwe's disease C96.0
acute infantile C96.0
nonlipid C96.0
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Langerhans cell histiocytosis
Langerhans cell histiocytosis is a disorder in which excess immune system cells called Langerhans cells build up in the body. Langerhans cells, which help regulate the immune system, are normally found throughout the body, especially in the skin, lymph nodes, spleen, lungs, liver, and bone marrow.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C96.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C96.0Overview
Is C96.0 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C96.0 group to?
When multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 11, 12, 13, 826, 827, 828, 829, 830, 843, 844, 845, with relative weights from 0.8516 to 5.4541 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C96.0 a CC or MCC?
CMS lists C96.0 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 47 closely related codes in its exclusion list.
What is the ICD-9 equivalent of C96.0?
Under the General Equivalence Mappings, multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis converts to ICD-9-CM 202.50 (ltr-siwe unsp xtrndl org). The mapping is approximate, so confirm the match fits the documentation.
What HCC is C96.0?
C96.0 (multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis) maps to CMS-HCC Category 21 (Lymphoma and Other Cancers), commonly written as HCC 21, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 10 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 21.
Does C96.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C96.0 adds a risk adjustment factor of about 0.671 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.493 to 0.739 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, and HCC 20) supersedes it when both are reported. See the full factor table on the HCC 21 category page.
