2026 ICD-10-CM Diagnosis Code G57.91Unspecified mononeuropathy of right lower limb

ICD-10-CM Codes›G00–G99›G50-G59›G57

ICD-10-CM G57.91
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G57.91 is a billable ICD-10-CM diagnosis code for unspecified mononeuropathy of right lower limb. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as disorder of right ilioinguinal nerve. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nerve and nerve root disorders.

Code Identity

ICD-10-CM Code
G57.91
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified mononeuropathy of right lower limb
Short Description
Unspecified mononeuropathy of right lower limb
Same as the full description in the CMS dataset.
Parent Code
G57.9
Unspecified mononeuropathy of lower limb

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG50-G59Nerve, nerve root and plexus disorders
CategoryG57Mononeuropathies of lower limb
This CodeG57.91Unspecified mononeuropathy of right lower limb

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Disorder of right ilioinguinal nerve
  • Genitofemoral neuropathy
  • Neuralgia of nerve of right lower limb
  • Neuroma of lower limb
  • Neuroma of right lower limb following surgery
  • Post surgical neuroma of lower limb
  • Right genitofemoral neuropathy
  • Right obturator neuropathy

Clinical ClassificationClinical

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

CCSR NVS017
Nerve and nerve root disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Peripheral Nerve Disorders

Nerves are like wires that carry messages back and forth between your brain and your body. Your peripheral nerves branch off from your brain and spinal cord and connect to all parts of your body, including your muscles and organs.

The full article covers:

  • What are peripheral nerves?
  • What are peripheral nerve disorders?
  • What causes peripheral nerve disorders?
  • What are the symptoms of peripheral nerve disorders?
  • How are peripheral nerve disorders diagnosed?
  • What are the treatments for peripheral nerve disorders?
  • Can peripheral nerve disorders be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G57.91 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
355.8 Mononeuritis leg NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G57.91Overview

Is G57.91 (Unspecified mononeuropathy of lower limb) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified mononeuropathy of right lower limb on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of G57.91?

Under the General Equivalence Mappings, unspecified mononeuropathy of right lower limb converts to ICD-9-CM 355.8 (mononeuritis leg NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.