Wear debris leading to local inflammatory reactive changes and osteolysis is a common complication after total knee arthroplasty (TKA). While massive osteolytic lesions may be commonly encountered in the revision setting, the appearance and location of these lesions rarely mimic expansile bone lesions. We report a case of severe osteolysis in a cemented TKA design, which presented as a pseudotumor of the fibular head. The diagnostic work-up and pathologic analysis are included in this report of a pseudotumor secondary to wear debris osteolysis.