2027 ICD-10-CM Diagnosis Code Q85.81PTEN hamartoma tumor syndrome

ICD-10-CM Codes›Q00-Q99›Q80-Q89›Q85

ICD-10-CM Q85.81
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Q85.81 is a billable ICD-10-CM diagnosis code for PTEN hamartoma tumor syndrome. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 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 6 closely related codes. The code is exempt from POA reporting. Coders also document this condition as cowden syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified congenital anomalies.

For Medicare Advantage risk adjustment, Q85.81 maps to CMS-HCC Category 23 (Prostate, Breast, and Other Cancers and Tumors) under the V28 model, adding a risk factor of about 0.186 for a community, non-dual, aged beneficiary in payment year 2027.

Code Identity

ICD-10-CM Code
Q85.81
Billable Status
Yes — Valid for Submission
Code Describes
PTEN hamartoma tumor syndrome
Short Description
PTEN hamartoma tumor syndrome
Same as the full description in the CMS dataset.
Parent Code
Q85.8
Other phakomatoses, not elsewhere classified

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ80-Q89Other congenital malformations
CategoryQ85Phakomatoses, not elsewhere classified
This CodeQ85.81PTEN hamartoma tumor syndrome

Present on Admission (POA)Billing

Q85.81 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Other congenital malformations (Q80-Q89).

Medicare Risk Adjustment (HCC)Billing

Q85.81 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.

CMS-HCC V28 Category (Payment Model)
HCC 23— Prostate, Breast, and Other Cancers and Tumors
Payment HCC · PY 2027 one of 234 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.186
community, non-dual, aged · ranges 0.186–0.237 across segments
Hierarchy
Superseded by HCC 17, HCC 18, HCC 19, HCC 20, HCC 21, and HCC 22
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 12
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 12 · ESRD (V21): HCC 12 · ESRD (V24): HCC 12
ESRD V21 weights: 0.046 dialysis, 0.156–0.194 functioning graft · ESRD V24 weights: 0.045 dialysis, 0.162–0.219 functioning graft
Part D (RxHCC)
RxHCC 22 — Prostate, Breast, Bladder, and Other Cancers and Tumors
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Cowden syndrome
  • Proteus like syndrome
  • PTEN hamartoma tumor syndrome

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Q85.81: its own notes plus those printed at Q85.8, Q85, and Chapter 17. 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.

  • PHTS
  • PTEN related Cowden syndrome

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Q85.8 Other phakomatoses, not elsewhere classified applies to 4 codes
  • Meckel-Gruber syndrome (Q61.9)
From Q85 Phakomatoses, not elsewhere classified applies to 11 codes
  • ataxia telangiectasia [Louis-Bar] (G11.3)
  • familial dysautonomia [Riley-Day] (G90.1)

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.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • inborn errors of metabolism (E70-E88)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

  • if applicable, genetic susceptibility to malignant neoplasm (Z15.0-)

Notes

General instructions on how these codes are used.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • Codes from this chapter are not for use on maternal records

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MAL010
Other specified and unspecified congenital anomalies
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • PTEN Hamartoma Tumor Syndrome

    a rare, autosomal dominant hereditary syndrome caused by germline mutation in the pten gene. it manifests with macrocephaly, neurocognitive deficits, hamartomas in multiple locations, polyposis, vascular abnormalities, and an increased risk of developing malignant tumors, particularly breast, thyroid, and endometrial carcinoma.

  • Neurocutaneous Syndromes

    a group of disorders characterized by ectodermal-based malformations and neoplastic growths in the skin, nervous system, and other organs.

Code History & ChangesHistory

Replacement Q85.81 replaces the following previously assigned code(s):

  • Q85.8 - Other phakomatoses, not elsewhere classified
FY 2023AddedAdded to the ICD-10-CM code setEffective October 1, 2022.
FY 2024RevisedCode revised
FY 2025–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Q85.81Overview

What is the ICD-10 code for PTEN hamartoma tumor syndrome?

The ICD-10-CM code for PTEN hamartoma tumor syndrome is Q85.81 (sometimes written as Q8581). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Q85.81 (Other phakomatoses, not elsewhere classified) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report PTEN hamartoma tumor syndrome on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Q85.81 group to?

When PTEN hamartoma tumor syndrome is the principal diagnosis on an inpatient stay, it groups to MS-DRG 844, 827, 829, 843, 828, 826, 830, 845, with relative weights from 0.8443 to 4.7560 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q85.81 a CC or MCC?

CMS lists Q85.81 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 6 closely related codes in its exclusion list.

Is Q85.81 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for PTEN hamartoma tumor syndrome on inpatient claims. The code appears in the Other congenital malformations (Q80-Q89) range of the CMS exempt list.

What HCC is Q85.81?

Q85.81 (PTEN hamartoma tumor syndrome) maps to CMS-HCC Category 23 (Prostate, Breast, and Other Cancers and Tumors), commonly written as HCC 23, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 12 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 22.

Does Q85.81 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, Q85.81 adds a risk adjustment factor of about 0.186 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.186 to 0.237 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, HCC 20, HCC 21, and HCC 22) supersedes it when both are reported. See the full factor table on the HCC 23 category page.