S90.521 (Blister (nonthermal), right ankle) compared with S90.529 (Blister (nonthermal), unspecified ankle), from the official CMS tabular data. S90.521 and S90.529 code the same condition on opposite sides.
Same condition; these differ only in which side is documented.
These codes share a category and title and differ only in the side affected. The documentation decides which applies, and a bilateral code is reported only where the code set provides one.
Source: ICD-10-CM tabular list (laterality variant derived from the code title)
Same condition, opposite side. S90.521 and S90.529 name the same condition on opposite sides of the body.
Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.
| S90.521Blister (nonthermal), right ankle | S90.529Blister (nonthermal), unspecified ankle | |
|---|---|---|
| Billing status | Non-billable header | Non-billable header |
| Classification | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) |
| Definition | Blister (nonthermal), right ankle is a non-billable ICD-10-CM category code (S90.521). | Blister (nonthermal), unspecified ankle is a non-billable ICD-10-CM category code (S90.529). |
| 7th character | The appropriate 7th character is to be added to each code from category S90 | The appropriate 7th character is to be added to each code from category S90 |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources