Haematomas are common and sarcomas are rare. However the absence of trauma or a light trauma should alert the clinician to the possibility that the abnormality may represent haemorrhage into a tumor and not just haematoma, even in a haemophilic patient. Clinical findings, sonography with Doppler assessment and magnetic resonance images with contrast administration will help in the differential diagnosis. The diagnosis of a high grade sarcoma must be considered in these patients and any doubt should be resolved with a biopsy to avoid tragic consequences of missed sarcoma.