What is ICD-10 code E24.3?

E24.3 is the ICD-10-CM diagnosis code for Ectopic ACTH syndrome. Cushing's syndrome caused by a tumor outside the pituitary gland (such as in the lungs or pancreas) that produces ACTH hormone. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E24.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E24.3 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. E24.3 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. E24.3 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does E24.3 map to under V28?

E24.3 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

What RAF reference is published for E24.3?

E24.3 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

What is the V28 vs V24 difference for E24.3?

E24.3 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

What documentation supports E24.3?

Document the location of the ectopic tumor; additional coding for the primary neoplasm may be required This is distinct from pituitary-dependent Cushing's disease E24.3 is not a CMS-HCC V28 payment code in the verified current source, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

2026 ICD-10-CM E24.3: Ectopic ACTH syndrome

E24.3 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupE24.3Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Disorders of other endocrine glands (E20-E35)

E24.3

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Ectopic ACTH syndrome

Cushing's syndrome caused by a tumor outside the pituitary gland (such as in the lungs or pancreas) that produces ACTH hormone.

Buddy Insight

Ectopic adrenocorticotropic hormone syndrome occurs when a non-pituitary tumor produces adrenocorticotropic hormone autonomously, causing severe and often rapidly progressive hypercortisolism.

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 030

HHS-HCC 030 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 23

Other Significant Endocrine a...

Code-level coefficient reference

RXHCC

Mapped

HCC 43

Pituitary, Adrenal Gland, and...

Code-level coefficient reference

Code Book Path

Official

E24Cushing's syndrome

E24.3Ectopic ACTH syndrome

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for E24.3 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E24.3 in this effective period.

Related Child Codes

Official

E24.0Pituitary-dependent Cushing's disease

E24.1Nelson's syndrome

E24.2Drug-induced Cushing's syndrome

E24.4Alcohol-induced pseudo-Cushing's syndrome

E24.8Other Cushing's syndrome

Includes

Official

ICD-10-CM does not list Includes notes for E24.3 in this effective period.

Excludes 1

Official

congenital adrenal hyperplasia (E25.0)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E24.3 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E24.3 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E24.3 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Document the source tumor type and location, adrenocorticotropic hormone levels (typically very high), cortisol levels, imaging confirming the ectopic source, potassium levels (often severely hypokalemic), and management of both the tumor and cortisol excess.

MEAT Support

HCC Buddy guidance

Audit Caution

HCC Buddy guidance

Always code the primary neoplasm separately in addition to E24.

This code identifies the endocrine syndrome, not the tumor itself. Ensure petrosal sinus sampling or other lateralization studies have confirmed the ectopic rather than pituitary source.

Common Mistakes

HCC Buddy guidance

E24.0 (pituitary-dependent Cushing disease where the source is pituitary, not ectopic), E24.8 (other Cushing syndrome), D38.1 (neoplasm of uncertain behavior of trachea/bronchus which may be the source tumor).

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is E24.3 an HCC code?

E24.3 is not in the CMS-HCC V28 or V24 community payment model. E24.3 has a separate mapping under the CMS-HCC ESRD model (HCC 23 (Other Significant Endocrine and Metabolic Disorders)) and the Part D RxHCC model (HCC 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders)); the applicable result needs member context. E24.3 also appears in the HHS-HCC commercial risk model (HCC 030 (HHS-HCC 030 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping.

Code: E24.3
Description: Ectopic ACTH syndrome
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

ESRDHCC 23, Other Significant Endocrine and Metabolic Disorders

Not separately weighted

RxHCCHCC 43, Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work E24.3 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for E24.3

For E24.3 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed E24.3 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E24.3 is the ICD-10-CM diagnosis code for ectopic acth syndrome. Cushing's syndrome caused by a tumor outside the pituitary gland (such as in the lungs or pancreas) that produces ACTH hormone. E24.3 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering disorders of other endocrine glands (e20-e35).

E24.3 has no mapping under the CMS-HCC V28 or V24 community payment models. E24.3 has a separate mapping under the CMS-HCC ESRD model (HCC 23 (Other Significant Endocrine and Metabolic Disorders)) and the Part D RxHCC model (HCC 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders)); the applicable result needs member context. E24.3 also appears in the HHS-HCC commercial risk model (HCC 030 (HHS-HCC 030 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.

Document the location of the ectopic tumor; additional coding for the primary neoplasm may be required.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for E24.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document the location of the ectopic tumor; additional coding for the primary neoplasm may be required
•This is distinct from pituitary-dependent Cushing's disease

Clinical Significance

Ectopic adrenocorticotropic hormone syndrome occurs when a non-pituitary tumor produces adrenocorticotropic hormone autonomously, causing severe and often rapidly progressive hypercortisolism. The most common sources are small cell lung carcinoma, bronchial carcinoid tumors, and pancreatic neuroendocrine tumors, making this diagnosis an important marker for occult malignancy.

Documentation Requirements

✓Document the source tumor type and location, adrenocorticotropic hormone levels (typically very high), cortisol levels, imaging confirming the ectopic source, potassium levels (often severely hypokalemic), and management of both the tumor and cortisol excess.

Commonly Confused Codes

•E24.0 (pituitary-dependent Cushing disease where the source is pituitary, not ectopic), E24.8 (other Cushing syndrome), D38.1 (neoplasm of uncertain behavior of trachea/bronchus which may be the source tumor).