Infection with HTLV-1 is a neglected condition, despite being the second most prevalent human retroviral infection worldwide after HIV-1 [1]. Current estimates are of 10 million people living with HTLV-1 globally, with high endemic regions located in Equatorial Africa, Latin America and the Caribbean, northeastern Iran, southwestern Japan and Australia [1], [2], [3]. Once acquired, either sexually, vertically or parenterally, HTLV-1 infection is lifelong. Although many HTLV-1-infected individuals are asymptomatic and unaware of their infection, roughly 10% will go to develop clinical manifestations. The time to onset of disease after HTLV-1 primary infection is generally very long (several decades) for adult T-cell leukemia/lymphoma (ATLL) whereas for HTLV-1-associate myelopathy (HAM) this time can be short is some cases, especially after blood transfusion or transplantation [4], [5], [6].

In 1989 Shimoyama classified ATLL into four clinical forms [7]. Whereas the acute and lymphoma forms are considered aggressive diseases, the chronic and smoldering forms are viewed as indolent conditions. In any clinical form, cutaneous involvement is associated with poorer prognosis [8]. Progression to acute or lymphomatous forms occurs in a significant proportion of patients originally presenting with indolent forms [9,10].

Herein, we discuss the main features of patients diagnosed to date with ATLL in Spain, a country of 47 million people, with a large migrant flow from regions in Latin America and Equatorial Africa where HTLV-1 is endemic.