[Tissue reactions to wear debris of joint prostheses. Diagnostic problems. Apropos of 2 cases].

We report two cases of tissue reactions to wear debris after large joint prostheses. In the first case, a septic loosening of a hip arthroplasty was suspected after emergence of an inguinal mass. In the second case, a patient with loose hip prosthesis had surgery for a prostatic adenocarcinoma and pelvic lymph nodes were discovered during surgery. They were first suspected to be metastatic carcinoma. These two diagnostic problems were resolved by histology which revealed sinusal histiocytic reaction to wear debris. The peculiar sign of this reaction is the presence of birefringent components such as polyethylene seen with polarized light. These problems will become more frequent in the future because of the increasing number of elderly patients who have had hip replacement and will undergo surgery for pelvic cancer. A close medico-surgical collaboration should help pathologists in such cases.