Periprosthetic metastatic carcinoma. Pitfalls in the management of two cases initially diagnosed as osteolysis.

Periprosthetic osteolysis is a well-described phenomenon associated with total hip arthroplasty. Two cases are presented in which apparently healthy patients developed lytic lesions adjacent to cementless hip implants. Despite atypical features, the lesions were initially attributed to wear debris-induced osteolysis, and it was discovered during revision surgery that metastatic tumor was present. For one patient, if the initial diagnosis had been correct, subsequent surgery and related complications may have been avoided. It is important to consider the entire differential of radiolucent bone lesions whenever a patient presents with periprosthetic osteolysis. If revision surgery is not warranted on the basis of loosening, then a thorough medical examination, close follow-up evaluation, and/or biopsy should be performed to rule out metastatic disease.