Adult T-cell leukaemia/lymphoma (ATLL) and T-cell leukemia virus type 1 (HTLV1)

Epidemiology The disease has a long latency, and affected individuals usually are exposed to the virus very early in life. The virus may be transmitted in breast milk, and through exposure to blood and blood products. The cumulative incidence of ATLL is estimated to be 2.5% among HTLV-1 carriers in Japan (1). Sporadic cases have been found in the United State and elsewhere. It occurs in adults only and the age at onset ranges from the 20s to the 80s, with an average of 58 years. The male to female ratio is 1.5:1 (2). While infection with HTLV-1 is a direct cause of ATLL, it can indirectly cause many other diseases via the induction of immunodeficiency and/or immune reaction, such as chronic lung disease, opportunistic lung infections, chronic renal failure, nonspecific dermatomycosis, nonspecific arthritis, HTLV-1 associated lymphadenitis, HTLV-1 uveitis, and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) (Table 1) (1). ATLL is endemic in several regions of the world, in particular Japan, the Caribbean basin and parts of Central Africa. The distribution of the disease is closely linked to the prevalence of HTLV-1 in the population.