Osteosarcoma as a second tumor after treatment for primary non-Hodgkin's lymphoma in a child with ataxia-telangiectasia: presentation of a case and review of possible pathogenetic mechanisms.

: Patients with ataxia-telangiectasia (A-T) and cancer are exposed to additional toxicity due to their underlying inability to repair chemotherapy-induced DNA damage. The authors report the development of osteosarcoma as a second neoplasia in a child with A-T who was treated, without being irradiated, for non-Hodgkin's lymphoma as a primary malignancy. This is the first report of osteosarcoma associated with A-T. The authors postulate that the mechanisms of carcinogenesis are common and independent of the different histopathology categories of these two neoplasias, and the underlying "canvas" of the A-T mutated gene was further triggered by chemotherapy, leading to the development of a second malignancy.