2025 Dec 13. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–.
ABSTRACT
Human T-lymphotropic viruses (HTLVs) are a family of human retroviruses recognized as oncoviruses. These viruses are known for causing immunosuppressive and inflammatory diseases. Among them, HTLV-1 is the most clinically significant and was the first pathogen demonstrated to induce malignant disease. HTLV-1 was identified in 1980 from a cell line derived from a patient with cutaneous T-cell lymphoma.
The discovery of HTLV-1 marked the first identification of a human retrovirus, sparking further investigations into the relationship between hematological malignancy and retroviruses. Today, HTLV-1 is regarded as one of the most potent oncogenic agents in humans. Although approximately 95% of infected individuals remain asymptomatic, about 5% may develop malignant, inflammatory, or opportunistic disease. Clinical manifestations include HTLV-1–associated myelopathy (HAM) and tropical spastic paraparesis (TSP).
HTLV-2, identified from hairy T-cell leukemia cell lines in 1982, is associated with a phenotype presentation similar to HAM/TSP in a small percentage of affected individuals. Unlike HTLV-1, however, HTLV-2 has not been clearly associated with malignancy. Similarly, HTLV-3 and HTLV-4 have not been shown to have causative relationships with malignancy.
HTLV-1 exhibits a strong oncogenic potential and carries a higher incidence of associated complications compared to other members of the HTLV family. The etiology, pathophysiology, evaluation, and management of HTLV-1 are fundamental to understanding its clinical significance.
