2027 ICD-10-CM Diagnosis Code C96.5Multifocal and unisystemic 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
C96.5 is a billable ICD-10-CM diagnosis code for multifocal and unisystemic Langerhans-cell histiocytosis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 642. 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 41 closely related codes. Coders also document this condition as bone xanthoma. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Non-Hodgkin lymphoma.
For Medicare Advantage risk adjustment, C96.5 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 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C96.5 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 2027.
Source: CMS Payment Year 2027 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.
- Bone xanthoma
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to C96.5: its own notes plus those printed at C96, block C81-C96, and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Hand-Schüller-Christian disease
- Histiocytosis X, multifocal
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- Functional activity
- All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
- Morphology [Histology]
- Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
- Primary malignant neoplasms overlapping site boundaries
- A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
- Malignant neoplasm of ectopic tissue
- Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name C96.5, its category, or a range that includes it.
Applicable To 2
These notes mention C96.5.
- Z80.7 Family history of other malignant neoplasms of lymphoid, hematopoietic and related tissuesConditions classifiable to C81-C90, C96.- names C96.-, which includes this code
- Z85.79 Personal history of other malignant neoplasms of lymphoid, hematopoietic and related tissuesConditions classifiable to C88-C90, C96 names C96, which includes this code
Excludes1 6
These codes carry an Excludes1 note naming C96.5: they are not reported together with it, unless the two conditions are unrelated.
- C96.0 Multifocal and multisystemic (disseminated) Langerhans-cell histiocytosismultifocal and unisystemic Langerhans-cell histiocytosis (C96.5)
- C96.6 Unifocal Langerhans-cell histiocytosismultifocal and unisystemic Langerhans-cell histiocytosis (C96.5)
- D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissueHand-Schüller-Christian disease (C96.5)
- D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissuehistiocytosis X, multifocal (C96.5)
- D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissueLangerhans-cell histiocytosis, multifocal (C96.5)
- C77 Secondary and unspecified malignant neoplasm of lymph nodesmalignant neoplasm of lymph nodes, specified as primary (C81-C86, C88, C96.-) names C96.-, which includes this code
Code First 1
These codes say to code first a condition named in the note, and C96.5 is one of the conditions named.
- N16 Renal tubulo-interstitial disorders in diseases classified elsewhere
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
unisystemic C96.5
multifocal C96.5
Syndrome See Also: Disease;
Schüller-Christian C96.5
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Hand-Schuller-Christian Disease
a multifocal, unisystem form of langerhans-cell histiocytosis. there is involvement of multiple sites in one organ system, most frequently the bone. patients are usually young children presenting with multiple destructive bone lesions.
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 C96.5 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C96.5Overview
What is the ICD-10 code for multifocal and unisystemic Langerhans-cell histiocytosis?
The ICD-10-CM code for multifocal and unisystemic Langerhans-cell histiocytosis is C96.5 (sometimes written as C965). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is C96.5 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report multifocal and unisystemic Langerhans-cell histiocytosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does C96.5 group to?
When multifocal and unisystemic Langerhans-cell histiocytosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 642 (inborn and Other Disorders of Metabolism), which carries a relative weight of 1.3226. Higher weights mean higher Medicare reimbursement.
Is C96.5 a CC or MCC?
CMS lists C96.5 as a CC (complication or comorbidity) for FY 2027. 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 41 closely related codes in its exclusion list.
Can C96.5 be reported with C96.0?
Not as a rule. The Excludes1 note on C96.5 lists "multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis (C96.0)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is C96.5?
C96.5 (multifocal and unisystemic 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 2027. 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 C96.5 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C96.5 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.
