Metal-containing lymph nodes following prosthetic replacement of osseous malignancy: potential role of MR imaging in characterisation

The identification of regional lympadenopathy in patients with bone maligna ncy treated by excision and insertion of a prosthesis usually indicates met astatic disease. We present two cases in which the lymphadenopathy was due to an uncommon but well-recognized foreign body reaction. This is secondary to the lymphatic uptake of metal debris shed by the prosthesis. In one cas e the metal within the excised lymph node could be demonstrated on in vitro MR imaging and in retrospect on the original in vivo scans. This condition should be considered when undertaking an MR examination in patients with b one malignancy treated by prosthetic replacement in whom there is a clinica l suspicion of metastatic spread to the regional lymph nodes.