We present the case of a 42-year-old woman with a recently acquired bleeding tendency. Coagulation studies and response to antifibrinolytic therapy suggested primary hyperfibrinogenolysis: markedly low levels of fibrinogen and α2-antiplasmin, normal levels of antithrombin III, protein C and protein S combined with an only borderline low number of platelets without evidence of microangiopathic haemolytic anaemia. A suspected causative adenocarcinoma of the lung was demonstrated. She was treated successfully with tranexamic acid and cryoprecipitate, until the tumor progressed and hyperfibrinogenolysis progressed to diffuse intravascular coagulation. Differential diagnosis of these coagulation disorders, with similar etiology, clinical and laboratory findings is reviewed. Therapeutic implications are discussed.