Histiocytic lymphadenitis associated with a large joint prosthesis.

Distinctive microscopic findings in enlarged axillary lymph nodes removed during modified radical mastectomy in a 76-year-old woman with a previous ipsilateral total shoulder joint replacement are described. The sinuses of the lymph nodes were distended by numerous large macrophages that had abundant granular eosinophilic cytoplasm. Periodic acid-Schiff staining was positive, and polarization microscopy revealed birefringent particles of polyethylene. These findings were diagnostic of the reactive lymphadenopathy that is seen uncommonly in lymph nodes draining large joint prostheses.