2027 ICD-10-CM Diagnosis Code M79.661Pain in right lower leg
ICD-10-CM Codes›M00–M99›M70-M79›M79
- Billable — Valid for Submission
- Not Chronic
M79.661 is a billable ICD-10-CM diagnosis code for pain in right lower leg. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 555 through 556. Coders also document this condition as bilateral calf pain. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Musculoskeletal pain, not low back pain.
This medical diagnosis code is frequently used in Family Practice, Internal Medicine, and Pediatrics medical specialties to designate conditions such pain in limb.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Bilateral calf pain
- Pain in bilateral lower legs
- Pain in calf
- Pain of left calf
- Pain of left lower leg
- Pain of right calf
- Pain of right lower leg
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M79.661: its own notes plus those printed at M79.6, M79, and Chapter 13. A note printed at a category, block or chapter applies to every code under it.
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.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name M79.661, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming M79.661: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 3
These codes carry an Excludes2 note naming M79.661: its condition is not part of those codes, and both may be reported when the patient has both.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Leg Injuries and Disorders
Your legs are made up of bones, blood vessels, muscles, and other connective tissue. They are important for motion and standing. Playing sports, running, falling, or having an accident can damage your legs. Common leg injuries include sprains and strains, joint dislocations, and fractures (broken bones).
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M79.661 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M79.661Overview
What is the ICD-10 code for pain in right lower leg?
The ICD-10-CM code for pain in right lower leg is M79.661 (sometimes written as M79661). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M79.661 (Pain in lower leg) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report pain in right lower leg on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M79.661 group to?
When pain in right lower leg is the principal diagnosis on an inpatient stay, it groups to MS-DRG 555, 556, with relative weights from 0.8210 to 1.2908 depending on complications. Higher weights mean higher Medicare reimbursement.
Can M79.661 be reported with F45.8?
Not as a rule. The Excludes1 note at M79, which applies to M79.661, lists "psychogenic rheumatism (F45.8)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of M79.661?
Under the General Equivalence Mappings, pain in right lower leg converts to ICD-9-CM 729.5 (pain in limb). The mapping is approximate, so confirm the match fits the documentation.
