Unprecedented Pseudotumor Formation in Granulicatella adiacens Periprosthetic Joint Infection

Periprosthetic joint infections remain among the most devastating complications after arthroplasty. While typically caused by common pathogens, rare organisms such as <i>Granulicatella adiacens</i> pose unique diagnostic and therapeutic challenges. We describe the first documented case of hip periprosthetic joint infection presenting as giant multilocular pseudotumor in a 68-year-old woman, 14 years after total hip arthroplasty. Despite normal inflammatory markers, aspiration and intraoperative samples identified <i>G adiacens</i> by matrix-assisted laser desorption ionization-time of flight. Multimodal surgical treatment with pseudotumor resection, neurolysis, staged component exchange, and targeted antibiotics led to full recovery and infection-free follow-up. This case highlights the need for heightened awareness of atypical pathogens, underscores the value of advanced diagnostics and interdisciplinary management, and raises the hypothesis that pseudotumor environments may facilitate infection.