ICD-10 Code L02.639 – Carbuncle of unspecified foot (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L02.639 – Carbuncle of unspecified foot
What it is
This code identifies a carbuncle on the foot when the provider does not specify the exact foot location. A carbuncle is a deeper skin infection made up of connected boils.
Clinical signs
Typical findings include a painful, swollen, red, and draining lesion with surrounding inflammation. Clinical features vary; refer to documentation if the record does not clearly describe the lesion as a carbuncle.
When to use this code
Use L02.639 when the documentation states carbuncle of the foot but does not identify the right or left foot, or a more specific site. It also fits when the note confirms a carbuncle and the location is only documented as “foot.”
If the record later specifies a more exact site or laterality, code that documented detail instead. Check documentation for whether the diagnosis is a carbuncle, furuncle, or another localized skin infection.
Do not use for
Do not use this code for a furuncle, abscess, or cellulitis unless the provider specifically documents carbuncle. Do not use it when the foot site is more specific and separately documented.
Coding tip
Always look for laterality and exact site in the note before defaulting to unspecified coding.