ICD-10 B09 Conversion to ICD-9 057.8

ICD-10 to ICD-9 Crossover Result

ICD-10 Code B09 representing "Unsp viral infection with skin and mucous membrane lesions" can be backward-mapped to its ICD-9 equivalent 057.8: "Viral exanthemata NEC". This conversion was generated using the latest General Equivalence Mappings (GEMs). While these mappings provide a standardized reference, not all ICD-10 codes have an exact ICD-9 match. Review the table below carefully and consider the clinical context when interpreting the mapped codes.

ICD‑10 Code

B09

Unsp viral infection with skin and mucous membrane lesions

ICD‑9 Code

057.8

Viral exanthemata NEC

Approximate Flag – This ICD-10 code does not have an exact ICD-9 equivalent. The matched code is the closest available option and may not fully capture the original diagnosis.

ICD‑10 Code

B09

Unsp viral infection with skin and mucous membrane lesions

ICD‑9 Code

057.9

Viral exanthemata NOS

Approximate Flag – This ICD-10 code does not have an exact ICD-9 equivalent. The matched code is the closest available option and may not fully capture the original diagnosis.

ICD‑10 Code

G40.B09

Juvenile myoclonic epilepsy, not intractable, w/o stat epi

ICD‑9 Code

345.80

Epilep NEC w/o intr epil

Approximate Flag – This ICD-10 code does not have an exact ICD-9 equivalent. The matched code is the closest available option and may not fully capture the original diagnosis.

About the General Equivalence Mappings Crossover Tool

The General Equivalence Mappings tool is a standardized crossover resource developed by the Centers for Medicare & Medicaid Services (CMS) and the National Center for Health Statistics (NCHS). It was created to help healthcare providers, coders, payers, and software vendors accurately transition between ICD-9 and ICD-10 diagnosis codes.

This ICD-10 to ICD-9 crosswalk tool supports both forward and backward mapping, making it valuable for converting legacy data, conducting audits, updating medical coding systems, and ensuring compliance with ICD-10 standards. GEMs are especially helpful when analyzing historical claims, aligning reimbursement logic, or migrating between systems.

Because not all ICD codes have a direct match, users should interpret each mapping carefully. Some ICD-10 to ICD-9 conversions may require clinical judgment or additional documentation to ensure coding accuracy. Not all ICD-10 to ICD-9 code conversions result in a single, exact match. In some cases, an ICD-10 code may map to multiple ICD-9 codes, especially when the original diagnosis requires more than one code to fully capture its meaning in the older coding system.