What is ICD-10 code E32.1?

E32.1 is the ICD-10-CM diagnosis code for Abscess of thymus. A bacterial infection of the thymus gland that causes pus accumulation and abscess formation. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E32.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E32.1 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. E32.1 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. E32.1 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.

What is the V28 vs V24 difference for E32.1?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. E32.1 was a payment HCC under V24 (Other Significant Endocrine and Metabolic Disorders) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting E32.1?

Document the causative organism if identified through culture or testing Code any associated complications such as mediastinitis or sepsis if present Because E32.1 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

E32.1: Abscess of thymus — ICD-10 | Other

ICD-10-CM Code View

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Code lookupE32.1Effective 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)

E32.1

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

Abscess of thymus

A bacterial infection of the thymus gland that causes pus accumulation and abscess formation.

Buddy Insight

Abscess of the thymus is an extremely rare infectious condition representing a focal collection of pus within the thymus gland.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Mapped

HCC 23

Other Significant Endocrine a...

RAF 0.230

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 23

Other Significant Endocrine a...

RAF 0.0

RXHCC

Mapped

HCC 43

Other Significant Endocrine a...

RAF 0.0

Code Trumping

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Code Book Path

Official

E32Diseases of thymus

E32.1Abscess of thymus

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for E32.1 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E32.1 in this effective period.

Related Child Codes

Official

E32.0Persistent hyperplasia of thymus

E32.8Other diseases of thymus

E32.9Disease of thymus, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for E32.1 in this effective period.

Excludes 1

Official

aplasia or hypoplasia of thymus with immunodeficiency (D82.1)
myasthenia gravis (G70.0)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E32.1 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E32.1 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E32.1 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation must include imaging findings confirming the abscess location and size within the thymus gland, culture and sensitivity results identifying the causative organism, and the patient's immunological status.

The provider should document any associated conditions such as mediastinitis, sepsis, or immunodeficiency that may have predisposed the patient to thymic infection.

MEAT Support

HCC Buddy guidance

The provider should document any associated conditions such as mediastinitis, sepsis, or immunodeficiency that may have predisposed the patient to thymic infection.

Audit Caution

HCC Buddy guidance

Do not code a thymic abscess without imaging or surgical confirmation, as mediastinal masses can be misidentified.

Ensure that the abscess is specifically located in the thymus rather than in adjacent mediastinal structures.

Code any identified infectious organism separately.

Do not use this code for thymic cysts, which are non-infectious and use E32.8.

Common Mistakes

HCC Buddy guidance

J85.3 (Abscess of mediastinum) should be considered if the abscess extends beyond the thymus into the mediastinal space.

E32.8 (Other diseases of thymus) is used for other thymic pathology without abscess formation.

B25-B49 (Mycoses and other infections) may be needed as additional codes to identify the causative organism.

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is E32.1 an HCC code?

Yes. E32.1 maps to Other Significant Endocrine and Metabolic Disorders under the V24 model but is not retained in V28.

HCC Category Mapping

V24HCC 23, Other Significant Endocrine and Metabolic Disorders

0.230

ESRDHCC 23, Other Significant Endocrine and Metabolic Disorders

0.000

RxHCCHCC 43, Other Significant Endocrine and Metabolic Disorders

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for E32.1

For E32.1to 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 E32.1 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E32.1 is the ICD-10-CM diagnosis code for abscess of thymus. A bacterial infection of the thymus gland that causes pus accumulation and abscess formation. E32.1 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).

Under the older CMS-HCC V24 model, E32.1 maps to Other Significant Endocrine and Metabolic Disorders (HCC 23) with a community, non-dual, aged base RAF weight of 0.230. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Document the causative organism if identified through culture or testing. Because E32.1 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E32.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document the causative organism if identified through culture or testing
•Code any associated complications such as mediastinitis or sepsis if present

Clinical Significance

Abscess of the thymus is an extremely rare infectious condition representing a focal collection of pus within the thymus gland. This can be life-threatening given the thymus's location in the mediastinum, with risk of spreading to adjacent vital structures including the heart and great vessels. Prompt diagnosis and treatment with antibiotics and possible surgical drainage are essential.

Documentation Requirements

✓Documentation must include imaging findings confirming the abscess location and size within the thymus gland, culture and sensitivity results identifying the causative organism, and the patient's immunological status.
✓The provider should document any associated conditions such as mediastinitis, sepsis, or immunodeficiency that may have predisposed the patient to thymic infection.

Commonly Confused Codes

•J85.3 (Abscess of mediastinum) should be considered if the abscess extends beyond the thymus into the mediastinal space.
•E32.8 (Other diseases of thymus) is used for other thymic pathology without abscess formation.
•B25-B49 (Mycoses and other infections) may be needed as additional codes to identify the causative organism.