Vitamin K deficiency presenting with hemarthrosis.

A breast-fed 25-day-old infant was hospitalized because of swelling and tenderness of the left leg, developed after mild rotary motion of the leg by his brother. Radiographic examination showed widening of the left articular hip joint space. On the day of admission, a presumptive diagnosis of septic arthritis was entertained, and antibiotic therapy was instituted. Following profuse bleeding from sites of skin punctures, coagulation studies were performed. Prothrombin time and partial thromboplastin time were prolonged. Administration of phylloquinone (vitamin K1) resulted in rapid normalization of coagulation. Differential diagnosis between hemarthrosis resulting from vitamin K deficiency and septic arthritis with disseminated intravascular coagulation is a matter of great importance in such patients.