Presumed transdermal superwarfarin toxicity in a pest control worker

A man in his early 60s presented with dyspnoea superimposed on a 2-month to 3-month history of spontaneous mucocutaneous bleeding. Laboratory testing revealed unmeasurably elevated international normalised ratio (INR) and activated partial thromboplastin time. CT of the neck demonstrated supraglottic soft tissue swelling with severe airway narrowing, requiring intubation for airway protection. Further history revealed occupational exposure to rodenticides during pest control work without consistent use of personal protective equipment. Markedly reduced activity of vitamin K-dependent clotting factors (II, VII, IX and X) supported a presumptive diagnosis of superwarfarin toxicity. Treatment with 4-factor prothrombin complex concentrate and vitamin K1 rapidly corrected the coagulopathy, although prolonged high-dose oral vitamin K1 was required because of recurrent INR elevation. He was discharged after 9 days and completed a 3-week vitamin K1 taper. This case highlights a rare presentation of presumed transdermal superwarfarin toxicity causing life-threatening coagulopathy and airway compromise.