Publication:

A rapidly advancing intraosseous angiosarcoma masquerading as an infected pathological periprosthetic fracture: a case report

We present a case of a rapidly progressive angiosarcoma that presented initially as a pathological fracture in our institution after a fall. Mdm A, a 74-year-old Chinese lady initially presented with non-specific thigh pain prior to an unwitnessed fall, following a recent bipolar hemiarthroplasty 3 months before current presentation. Blood markers were grossly within acceptable limits and computed tomography (CT) scan revealed displaced greater and lesser trochanteric periprosthetic fractures with subsidence of femoral stem, and findings suggestive of intramuscular haematomas. She subsequently turned septic on day of planned surgery for a revision arthroplasty with markedly raised inflammatory markers. Revision surgery was postponed, with repeat imaging noting evolving fluid collections suspicious of an infected prosthetic joint infection (PJI). Joint washout for presumptive PJI performed 1-week later yielded negative histopathology and cultures. She developed respiratory compromise a few days later. CT-thorax revealed bilateral pleural effusions with small spontaneous haemo-pneumothoraces which again yielded negative cultures and cytology. Eventually a repeat CT-hip 1-month post admission showed new soft tissue lesions in the superficial muscle layers. Biopsies performed returned as intermediate grade angiosarcoma with positive CD31 and ERG stainings. This is the first case study to describe an aggressive metastatic angiosarcoma mimicking a PJI on initial presentation. Angiosarcomas are very rare and presentations may also be highly varied. Diagnosis of angiosarcoma may be made difficult by the absence of clear lesions to biopsy, as in this particular case. A high clinical suspicion of a pathological periprosthetic fracture is needed when diagnosing patients who present atypically for PJIs.