ICD-10 Code B97.33 – Human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B97.33 – Human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere
What it is
This code identifies HTLV-I as the infectious cause of another condition classified elsewhere. Use it when the record links HTLV-I to a specific disease, but the disease itself is coded separately.
Clinical signs
Clinical features vary; refer to documentation. HTLV-I may be associated with chronic infection, neurologic disease, or other HTLV-related manifestations, but you should code only what is clearly documented.
When to use this code
Use B97.33 when the provider states that HTLV-I is the cause of a documented condition and that condition has its own ICD-10-CM code. Apply it as an additional code, not as the primary diagnosis, unless instructed otherwise by the record.
It is appropriate when the chart explicitly connects HTLV-I with the patient’s illness, such as “due to HTLV-I” or “HTLV-I infection causing disease.” Check documentation if the causal relationship is unclear.
Do not use for
Do not use this code for a general history of HTLV-I infection without a current related disease. Do not use it when the chart does not identify HTLV-I as the cause.
Coding tip
Pair B97.33 with the code for the specific HTLV-I-related condition documented in the record.