ICD-10-CM 2027
ICD-10 code for Phakomatosis
From the official ICD-10-CM alphabetic index entry “Phakomatosis”. Page updated September 29, 2026.
About coding Phakomatosis
The ICD-10-CM code for Phakomatosis is Q85.9 (Phakomatosis, unspecified). The official index lists 2 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on Q85.9.
Within Q85, choose Q85.9 (Phakomatosis, unspecified) only when documentation doesn't support a more specific option: neurofibromatosis (nonmalignant) (Q85.0), Tuberous sclerosis (Q85.1) and other phakomatoses, not elsewhere classified (Q85.8).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 826 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with MCC, relative weight 4.7581), DRG 827 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with CC, relative weight 2.3896), DRG 828 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures without CC/MCC, relative weight 1.6955), DRG 829 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures with CC/MCC, relative weight 3.1281), DRG 830 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures without CC/MCC, relative weight 1.4859), DRG 843 (Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with MCC, relative weight 1.9453) and 2 more, in MDC 17 (Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific Phakomatosis codes (official index)
Common questions about Phakomatosis ICD-10 codes
What is the ICD-10 code for Phakomatosis?
- Q85.9 — Phakomatosis, unspecified. More specific codes apply when the documentation supports them: Q85.1, Q85.89.
What is the ICD-10 code for bourneville's phakomatosis?
- Q85.1 — Tuberous sclerosis.
Is Q85.9 billable?
- Yes. Q85.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Q85.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict Q85.9 as a principal diagnosis.
Is Q85.9 a CC or MCC?
- Q85.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.