C75.1
BillableMalignant neoplasm of pituitary gland
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C75.1 an HCC code?
Yes. C75.1 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24).
HCC Category Mapping
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 C75.1
For C75.1 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 C75.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C75.1 is the ICD-10-CM diagnosis code for malignant neoplasm of pituitary gland. Cancer that starts in the pituitary gland, a small gland at the base of the brain that controls many hormones in the body. C75.1 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of thyroid and other endocrine glands (c73-c75).
Under the CMS-HCC V28 risk adjustment model, C75.1 maps to Lung and Other Severe Cancers (HCC 20) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, C75.1 maps to Lymphoma and Other Cancers (HCC 10) with a community, non-dual, aged base RAF weight of 0.675. 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.
Pituitary carcinomas are extremely rare; confirm malignant diagnosis and distinguish from benign pituitary adenomas in documentation. Because C75.1 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 C75.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Pituitary carcinomas are extremely rare; confirm malignant diagnosis and distinguish from benign pituitary adenomas in documentation
- •Document any functional status (hormone-secreting vs. non-secreting) as this impacts clinical management and may require additional codes
Clinical Significance
Malignant neoplasm of the pituitary gland represents pituitary carcinoma, which is defined by the presence of craniospinal or systemic metastases. This is extremely rare — most pituitary tumors are benign adenomas. Pituitary carcinoma causes hormonal imbalances and may compress the optic chiasm, causing visual field defects. Accurate coding is essential to distinguish this from the much more common benign pituitary adenoma.
Documentation Requirements
- ✓Pathology confirming pituitary carcinoma with evidence of metastatic disease (defining criterion)
- ✓Documentation of hormonal hypersecretion or hypopituitarism
- ✓Imaging showing sellar/suprasellar mass and any metastatic disease
- ✓Visual field assessment results
- ✓Current treatment status (surgery, radiation, medical therapy)
Commonly Confused Codes
- •D35.2 — Benign neoplasm of pituitary gland: Pituitary adenomas are benign and vastly more common than carcinoma
- •D44.3 — Neoplasm of uncertain behavior of pituitary gland: Use when malignancy is not confirmed
- •E22.0 — Acromegaly and pituitary gigantism: Hormonal condition from growth hormone excess, usually from benign adenoma
- •E23.0 — Hypopituitarism: May result from pituitary tumor but is a separate endocrine condition
- •C75.2 — Malignant neoplasm of craniopharyngeal duct: Adjacent sellar region tumor with different origin