2026 ICD-10-CM Diagnosis Code S60.421ABlister (nonthermal) of left index finger, initial encounter
S60.421A is a billable ICD-10-CM diagnosis code for blister (nonthermal) of left index finger, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 606 through 607, 963 through 965. Coders also document this condition as blister of finger of left hand with infection. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Superficial injury; contusion, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Blister of finger of left hand with infection
- Left hand blister with infection
- Left index finger blister with infection
- Superficial injury of left index finger
- Traumatic blister of finger of left hand
- Traumatic blister of index finger
- Traumatic blister of left hand
- Traumatic blister of left index finger
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Superficial injury of wrist, hand and fingers (S60). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Blisters
Blisters are fluid-filled sacs on the outer layer of your skin. They form because of rubbing, heat, or diseases of the skin. They are most common on your hands and feet.
The full article covers:
- What are blisters?
- What causes blisters?
- What are the treatments for blisters?
- Can blisters be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S60.421A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S60.421AOverview
Is S60.421A (Blister (nonthermal) of left index finger) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report blister (nonthermal) of left index finger, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S60.421A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for blister (nonthermal) of left index finger, such as an emergency visit or first evaluation.
What MS-DRG does S60.421A group to?
When blister (nonthermal) of left index finger, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 606, 607, 963, 964, 965, with relative weights from 0.9064 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S60.421A?
Under the General Equivalence Mappings, blister (nonthermal) of left index finger, initial encounter converts to ICD-9-CM 915.2 (blister finger). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
