Revision Total Hip Arthroplasty Complicated by Metastatic Malignant Gastrointestinal Stromal Tumour

摘要

Periprosthetic malignancy causing failure of total hip arthroplasty is a rare entity. Metastasis of malignant tumour to the proximity of orthopaedic implants is even more uncommon. We present a case of a 74-year-old female with an infected Austin Moore prosthesis, requiring a two-stage revision total hip arthroplasty. Within 2 years postoperatively, erosion of the lesser trochanter was noted. Further revision surgery was performed with the insertion of a cement spacer. Despite the expectation of an infected prosthesis, intraoperative frozen section showed sarcoma and the final pathology was metastasis of a recurrent gastrointestinal stromal tumour (GIST). Metastatic GIST to total hip prosthesis had not been reported previously and this case illustrates how intraoperative frozen section can aid diagnosis and management. We also highlighted some diagnostic clues, differentiating this rare diagnosis from septic loosening and osteolysis. Malignant infiltration should be considered as a differential diagnosis in failed total hip arthroplasty, especially in patients with a previous history of malignancy.