2027 ICD-10-CM Diagnosis Code Q85.9Phakomatosis, unspecified
ICD-10-CM Codes›Q00-Q99›Q80-Q89›Q85
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 23
- POA Exempt
- Chronic Condition
Q85.9 is a billable ICD-10-CM diagnosis code for phakomatosis, unspecified. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified congenital anomalies.
For Medicare Advantage risk adjustment, Q85.9 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
Code Classification
Present on Admission (POA)Billing
Q85.9 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
Q85.9 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.
- Bilateral congenital hamartoma of irises
- Congenital hamartoma
- Congenital hamartoma of iris
- Congenital hamartoma of iris of left eye
- Congenital hamartoma of iris of right eye
- Congenital hamartoma of skin
- Connective tissue nevus of skin
- Hamartoma
- Hamartoma of duodenal gland
- Hamartoma of intestine
- Hamartoma of small intestine
- Hamartoma of tongue
- Heart defect, tongue hamartoma, polysyndactyly syndrome
- Linear basal cell nevus
- Neoplasm and/or hamartoma
- Neurocutaneous syndrome
- Paving stone nevus
- Port-wine stain in proteus syndrome
- Port-wine stain of skin
- Proteus syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q85.9: its own notes plus those printed at 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.
- Hamartosis NOS
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.
- 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.
Hamartosis Q85.9
Phakomatosis See Also: specific eponymous syndromes; Q85.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Neurocutaneous Syndromes
a group of disorders characterized by ectodermal-based malformations and neoplastic growths in the skin, nervous system, and other organs.
Patient EducationClinical
Genetic Disorders
Genetic disorders are health conditions caused by changes (also called mutations or variants) in your genes. Genes are parts of DNA found in your cells that carry instructions for how your body grows, develops, and functions. Many genes tell your body how to make proteins, which are needed for your body to work properly.
The full article covers:
- What are genetic disorders?
- What causes genetic disorders?
- What are the types of genetic disorders?
- What are the different ways a genetic disorder can be inherited?
- How are genetic disorders diagnosed?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q85.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q85.9Overview
What is the ICD-10 code for phakomatosis, unspecified?
The ICD-10-CM code for phakomatosis, unspecified is Q85.9 (sometimes written as Q859). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q85.9 (Phakomatoses, not elsewhere classified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report phakomatosis, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q85.9 group to?
When phakomatosis, unspecified 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 Q85.9 a CC or MCC?
CMS lists Q85.9 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 Q85.9 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 phakomatosis, unspecified on inpatient claims. The code appears in the Other congenital malformations (Q80-Q89) range of the CMS exempt list.
What HCC is Q85.9?
Q85.9 (phakomatosis, unspecified) 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 Q85.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, Q85.9 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.
