Abstract
CASE: A 76-year-old female with a history of multiple falls on the patella presented with worsening knee pain, swelling, and reduced range of motion. Radiographs revealed tricompartmental osteoarthritis and subtle erosion of the posterior cortex of the patella that was missed by the referring orthopedist and radiologist. Her persistent pain prompted an MRI, revealing a mass later confirmed to be primary diffuse large B-cell lymphoma of the patella after biopsy and appropriate metastatic workup. CONCLUSION: Primary B-cell patellar lymphoma is a rarely described cause of knee pain requiring broad differential diagnosis and multidisciplinary workup in order to avoid erroneous treatment and ensure prompt oncologic treatment.