Case Report: a giant gastric stromal tumor spontaneously hemorrhaged after freeze-dried rabies vaccine (Vero-cells) injection for human use.

The freeze-dried rabies vaccine (Vero-cells) is generally safe. We present a rare case of a 44-year-old man who developed spontaneous intraperitoneal hemorrhage from a giant gastric gastrointestinal stromal tumor (GIST) shortly after receiving this vaccine. Emergency surgery was performed, and postoperative pathological and immunohistochemical analysis confirmed the diagnosis of a high-risk gastric GIST. The patient declined postoperative adjuvant therapy with imatinib. Follow-up evaluations at one year postoperatively indicated stable disease, and he has remained progression-free for 16 months to date, underscoring the indolent biology of gastric GISTs even in high-risk cases. This case serves as an important reminder for clinicians to consider underlying occult GISTs when evaluating acute abdominal symptoms after vaccination. Through this patient's journey, we emphasize the significance of performing comprehensive computed tomography (CT) examinations in patients with giant GISTs prior to rabies vaccination, and underscore the crucial need for heightened vigilance and close monitoring following administration of the freeze-dried rabies vaccine (Vero cells). Potential mechanisms that have been hypothesized to explain spontaneous tumor hemorrhage in this context include vaccine-induced inflammatory cytokine surges and hemodynamic changes. Although a rare case of rabies vaccine-associated thrombocytopenia has been reported, evidence for this mechanism remains limited. Further studies are warranted to clarify the relationship between vaccination and tumor rupture.