A 2 year-old boy was brought for examination of his swollen right thigh. His mother reported that the swelling occurred following an incident when, during a game when she was chasing him, he was obliged to sit down heavily, landing with his right buttock on the floor. The question was whether this was unilateral edema, thrombophlebitis or hematoma. The presence of microecchymoses on the posterior aspect of the thigh is evidence of a hemorrhagic manifestation. Elicitation of the family history revealed that a first cousin of the boy on his mother's side is a known hemophiliac. The investigation of his hemostatic mechanism showed deficiency of factor VIII (FVIII:C= 4%). In the figure 1 on scan 3 and in the figure 2.