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 Granulicatella adiacens 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 G adiacens 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.