T25.721 Corrosion of third degree of right foot

ICD-10-CM Code T25.721: Corrosion of third degree of right foot

ICD-10-CM code T25.721 represents a third-degree corrosion of the right foot. It falls under the broader category of burns and corrosions of the ankle and foot. The base code requires a seventh character to define the encounter, such as initial, subsequent, or sequela. This code is distinct from corrosions of the toe nails. 2 4 5

Plain-language overview

Code T25.721 identifies a third-degree corrosion located on the right foot. This classification is part of the ICD-10-CM system, which is used to document injuries, poisoning, and other consequences of external causes. 4 5

What this code represents

The code T25.721 belongs to category T25 for burn and corrosion of ankle and foot, and specifically to subcategory T25.7 for corrosion of third degree of ankle and foot. It is listed within Chapter 19 under burns and corrosions of external body surface specified by site. 5

Coding details

The base code T25.721 is expanded with a seventh character to specify the encounter type. The valid extensions include A for initial encounter, D for subsequent encounter, and S for sequela. 2

The T25.721 code for the right foot is listed alongside other specific right lower extremity corrosions. These related codes include T24.701 for the right lower limb except ankle and foot, and T25.791 for multiple sites of the right ankle and foot. 2

Documentation considerations

The provided sources list T25.721 and its corresponding encounter characters. The excerpts do not state the specific clinical documentation elements needed to select this code. 2 4

What the sources add

The Centers for Medicare and Medicaid Services transmittal provides the specific encounter extensions for T25.721, while the Vero source outlines the broader category and subcategory hierarchy. Both sources confirm the code describes a third-degree corrosion of the right foot. 2 5

The Vero source lists an Excludes2 note for corrosion of third degree of toe(s) nail under T25.73. A separate CMS article lists T25.732S for a third-degree corrosion of left toe(s) nail, showing a distinct code set for toe nail injuries. 3 5

Coverage and utilization context

The CMS article appears in a database concerning surgical treatment of nails and lists a related toe nail corrosion code. The provided excerpts do not establish payer-specific coverage rules or utilization guidelines for the T25.721 code. 3

Sources

1. Retrospective Analysis of Burn Injuries in Children with Autism Spectrum Disorder — pmc.ncbi.nlm.nih.gov; accessed 2026-07-26.
2. CMS Manual System - Pub 100-20 One-Time Notification — cms.gov; accessed 2026-07-26.
3. Article - Billing and Coding: Surgical Treatment of Nails (A52998) — cms.gov; accessed 2026-07-26.
4. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-26.
5. ICD-10-CM T25.72: Corrosion of third degree of foot | Vero — veroscribe.com; accessed 2026-07-26.