Non‐Hodgkin Lymphoma Secondary to Hodgkin Lymphoma in an Adult Patient With Nijmegen Breakage Syndrome

Nijmegen breakage syndrome (NBS) is a rare inherited autosomal treated with a tailored regimen of chemotherapy in our recessive DNA repair disorder characterized by microcephaly, growth and mental retardation, immunodeficiency, radiation hypersensitivity, and increased incidence of lymphoid malignancies. Nijmegen breakage syndrome is characterized by a 5-bp deletion on exon 6 in the NBN (formerly NBS1) gene on chromosome 8q21. The hypomorphic mutation leads to expression of a truncated and insufficiently functioning protein (p70-Nibrin) with a 26-kDA N-terminal and a 70-kDa fragment. Nibrin forms a complex with MRE11 and RAD50 (MRN), which is involved in processing DNA double-strand breaks. Thus, dysfunctional nibrin leads to impaired cellular DNA damage response. Consequently, NBS patients harbor an increased risk of developing hematological malignancies and are extremely vulnerable to ionizing radiation (IR). So far mostly pediatric NBS patients have been described, since lymphoid malignancies are often fatal before adulthood. To our best knowledge, we here report on diagnostic procedures and therapy of the first adult NBS patient with a non-Hodgkin lymphoma (NHL) secondary to a successfully treated classical Hodgkin lymphoma (cHL) who achieved a second complete remission (CR). The patient had been diagnosed with NBS at birth and had been registered in the NBS Registry (patient no. 45). In 2011, the patient was diagnosed with stage IV nodular sclerosis cHL and