Occult brodifacoum poisoning presenting as a massive intramuscular hematoma

Introduction Brodifacoum induces coagulopathy after absorption, causing severe systemic hemorrhage. Occult hemorrhage may delay diagnosis and treatment.Case summary A 56-year-old man was referred to our hospital with worsening right thigh swelling for nine days. He had no recent trauma or medications affecting his INR. On admission, laboratory tests revealed an elevated PT of 75 s and INR of 9.05, and serum brodifacoum concentration of 25 µg/L (0.0478 µmol/L). Imaging confirmed a large right thigh hematoma. Forty-three days prior to this presentation, he had presented with life-threatening gastrointestinal bleeding, liver injury, and coagulopathy, which resolved with phytomenadione (Vitamin K1, 40 mg daily for two days, then 120 mg daily for four days) and supportive care. Eighteen days prior to this presentation, the coagulopathy recurred (PT 60.1 s, INR 6.82), but he declined further vitamin K1 treatment.Images Ultrasound and magnetic resonance imaging revealed a large intramuscular hematoma in the right anterior thigh, without cutaneous ecchymosis.Conclusion Brodifacoum poisoning can cause life-threatening hemorrhages. In some cases, a large intramuscular hematoma may be the only clinical manifestation, resulting from the underlying coagulopathy, and failure to recognize this may delay appropriate management.