HTLV-II as the cause of diseases classified elsewhere

This code identifies the presence of Human T-cell lymphotrophic virus, type II (HTLV-II) when it is determined to be the underlying cause of another disease process. HTLV-II is a retrovirus that can lead to various neurological, hematological, and inflammatory conditions. This code is used to establish the etiologic link between the HTLV-II infection and the manifestation of a secondary disease.

Use this code when documentation clearly indicates HTLV-II as the causative agent for a condition classified elsewhere in ICD-10-CM. This typically applies to patients diagnosed with HTLV-II infection who subsequently develop associated diseases, such as HTLV-II-associated myelopathy or certain lymphomas. Physician documentation explicitly stating the causal relationship is essential.

• Always sequence this code as a secondary diagnosis, following the code for the specific disease caused by HTLV-II.
• Ensure documentation explicitly links HTLV-II to the other condition; mere presence of HTLV-II is insufficient.
• Do not confuse with HTLV-I infections (B97.33) or unspecified HTLV infections (B97.35).