Kikuchi's disease is a rare self-limiting lymphoproliferative condition of unknown aetiology, characterised by acute or subacute necrotising lymphadenitis. It is a benign condition that can mimic malignant lymphoma. In this report, a case of Kikuchi's disease associated with a chromosomal abnormality is described. This is the first report in the literature of such a case and it highlights an important learning point; benign lymphoproliferative conditions can be associated with chromosomal abnormalities that are more typically associated with malignant lymphoproliferative conditions such as malignant lymphoma. The report illustrates the necessity for interpreting cytogenetic data in the relevant clinical and histopathological context in a multidisciplinary setting to avoid misdiagnosis and inappropriate treatment.