Variable degrees of T cell deficiency in ataxia-telangiectasia (AT) progressively worsen with time and death from malignant lymphoma is a common terminal event. T-cell lymphoma as the first manifestation of AT has never been reported.A 22 month-old girl born to consanguineous parents, was treated for a thoracic T-cell lymphoma and remained in first complete remission, with a follow-up of 4 years. Prior to chemotherapy, cytogenetic studies on blood showed clonal rearrangements including t(7p;14q), T(2p;7q) and inv (7), while karyotype showed 6q- and 1p-mitoses on bone marrow blasts. Hypotonia became evident at 3 years. One year later, the neurological status deteriorated. The patient presented also severe respiratory tract infections. At that time, immunological investigations showed hypo IgG2, very low T4 lymphocytes level, all harbouring the CD45 RO phenotype. Increase in alpha-foetoprotein level, the ocular movements and the study of DNA synthesis after exposure to gamma-rays confirmed the diagnosis of AT.In cases of childhood lymphoid neoplasia, AT should be considered whenever parental consanguinity, T-cell proliferation and/or unexpected toxic therapeutic responses are noted.
