S90.521A — Blister (nonthermal), right ankle, initial encounter
Is S90.521A billable?
Yes — S90.521A is billable for FY2027. S90.521A is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. S90.521A may be submitted for encounters from October 1, 2026 through September 30, 2027.
S90.521A at a glance
| Code | S90.521A |
|---|---|
| Description | Blister (nonthermal), right ankle, initial encounter |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
| 7th character "A" | initial encounter |
What does the 7th character "A" mean in S90.521A?
In S90.521A, the 7th character A means initial encounter. The 7th character is required for S90.521A to be a valid, complete code.
Same condition, different episode of care — switch the 7th character:
Which MS-DRGs does S90.521A group to?
S90.521A sits in MDC 09 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 606Minor Skin Disorders with MCCmedical
- 607Minor Skin Disorders without MCCmedical
How is S90.521A listed in the Alphabetic Index?
The Alphabetic Index lists these routes under S90.52, the nearest indexed parent of S90.521A. Use them to find the family, then select the specific code.
- Blister › ankle (nonthermal)
Use additional code — inherited from Chapter 19
Report an additional code alongside S90.521A to fully describe the condition. S90.521A is sequenced first.
- code to identify any retained foreign body, if applicable (Z18.-)
Excludes2 — not included here — inherited from Chapter 19
The conditions below are not part of S90.521A, but a patient may have both at the same time. When documentation supports it, S90.521A and the excluded code may both be reported.
Excludes2 — not included here — inherited from S90-S99
The conditions below are not part of S90.521A, but a patient may have both at the same time. When documentation supports it, S90.521A and the excluded code may both be reported.
How long has S90.521A existed?
S90.521A has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.