Epiphyseal lymphoid infiltrates of the knee in adolescents

We present three adolescents with focal lesions of the distal femur that were shown to be benign aggregates of small lymphocytes and plasma cells of unknown origin. The patients were within the age of 12 and 14 years. All lesions presented with similar MRI findings and provided the same histopathological findings in the biopsy. Although all lesions increased in size, only one patient remained symptomatic and underwent subsequent tumor resection. To our best knowledge, tumor or pseudotumoral epiphyseal lymphoid infiltrates as seen in these three patients have not previously been described. We recommend a biopsy to rule out a malignant tumor or an infection. Observation, without further invasive testing in asymptomatic patients, is recommended until the resolution of the lesions. However, if a lesion becomes symptomatic, surgical resection should be considered.