Histiocytosis of regional lymph nodes associated with hip replacement.

Five cases of pronounced histiocytic reaction in pelvic lymph nodes after hip replacement are demonstrated. Two patients subsequently underwent radical prostatectomies with bilateral lymph node dissections for adenocarcinoma. In three patients, the change was found during autopsy. The sinuses and interfollicular spaces were distended by numerous large macrophages that had bulky eosinophilic cytoplasm. The cells displayed immunoreactivity to KP1 antigen, alpha-1-antitrypsin and lysozyme, providing support for their histiocytic derivation. Polarization microscopy revealed birefringent needle-like particles in their cytoplasm. We think that the histologic appearance of lymph nodes represents a foreign body reaction to fragments of polyester or polyethylene derived from joint prostheses. It is necessary to be aware of this characteristic foreign body reaction in order to avoid confusion with other types of lymph node histiocytosis or with a metastatic tumor.