M79.66 – Pain in lower leg

ICD-10-CM 2027 diagnosis code · Other soft tissue disorders

Non-billable header

ICD-10-CM code M79.66

Code: M79.66 (claims format: M7966)
Description: Pain in lower leg
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 13. Diseases of the musculoskeletal system and connective tissue (M00-M99)
Block: M70-M79 Other soft tissue disorders
Parent codes: M79 › M79.6

Billable codes under M79.66

M79.66 is a header code and cannot be used on claims. Choose the most specific code:

M79.661 – Pain in right lower legBillable
M79.662 – Pain in left lower legBillable
M79.669 – Pain in unspecified lower legBillable

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

M79 – Other and unspecified soft tissue disorders, not elsewhere classified

Excludes1 (not coded here):

psychogenic rheumatism (F45.8)
soft tissue pain, psychogenic (F45.41)

M79.6 – Pain in limb, hand, foot, fingers and toes

Excludes2 (not included here):

pain in joint (M25.5-)

Index terms for M79.66

Entries in the ICD-10-CM alphabetic index that lead to this code:

Pain, limb, lower, lower leg

Related codes in M79.6

M79.60 – Pain in limb, unspecifiedHeader
M79.62 – Pain in upper armHeader
M79.63 – Pain in forearmHeader
M79.64 – Pain in hand and fingersHeader
M79.65 – Pain in thighHeader
M79.67 – Pain in foot and toesHeader

Frequently asked questions

What is ICD-10 code M79.66?

M79.66 is the ICD-10-CM code for pain in lower leg, in the block M70-M79 (Other soft tissue disorders).

Is M79.66 a billable code?

No. M79.66 is a header code with more specific child codes; report one of the billable codes listed above.

What category does M79.66 belong to?

It belongs to category M79 – Other and unspecified soft tissue disorders, not elsewhere classified.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.