ICD-10 Code B97.34 – Human T-cell lymphotrophic virus, type II [HTLV-II] as the cause of diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B97.34 – Human T-cell lymphotrophic virus, type II [HTLV-II] as the cause of diseases classified elsewhere
What it is
This code identifies HTLV-II as the documented cause of another condition classified elsewhere. Use it when the record links HTLV-II infection to the patient’s diagnosed disease, not as the primary disease code.
Clinical signs
Clinical features vary; refer to documentation. Standard references describe HTLV-II as a retroviral infection that may be asymptomatic or associated with neurologic or hematologic findings, but the code itself depends on documented causation.
When to use this code
Use B97.34 when the provider states HTLV-II is the cause of a separately coded condition, such as a related infectious or neurologic diagnosis. Pair it with the manifestation or underlying disease code as directed by the record.
If HTLV-II is only mentioned in history or screening without a current causal link, this code is usually not appropriate. Check documentation for explicit wording such as “due to,” “caused by,” or “associated with.”
Do not use for
Do not use this code for HTLV-I infection, unspecified HTLV infection, or a disease that is not documented as caused by HTLV-II. Check documentation if the chart does not clearly establish the relationship.
Coding tip
Always code the confirmed manifestation first or alongside B97.34, and verify that HTLV-II is named as the cause in the provider note.