Histiocytic lymphadenopathy secondary to metallosis following endoprosthetic replacement in osteosarcoma patient – a potential diagnostic pitfall

Abstract

We present the case of a 43-year old patient with inguinal lymphadenopathy 22 years after distal femoral resection for osteosarcoma with cemented distal femoral replacement reconstruction. Seven years after initial distal femoral resection patient underwent metal on metal hip resurfacing arthroplasty on the affected side. Twenty years after distal femoral replacement and 13 years after metal on metal hip resurfacing procedure, the patient underwent left inguinal lymph­adenectomy for an enlarged mass of inguinal lymph nodes on suspicion for a sarcoma recurrence. On microscopic ex­amination, excised lymph nodes were massively infiltrated with macrophages and multinucleated giant cells with focal asteroid bodies. An examination in polarized light revealed numerous metal particles; immunohistochemical stainings confirmed reactive character of changes, and florid metal-related sinus histiocytosis was finally diagnosed. Microscopic assessment of lymph nodes in the course of malignancy is a standard procedure; we present a rare case of non-neoplastic lymph node enlargement due to the late onset of metallosis, which might be a diagnostic challenge.