Spontaneous hematomas are rare and can present with acute or chronic symptoms. Our patient presented with deep vein thrombosis of the lower extremity associated with a spontaneous pelvic hematoma. This lesion was radiologically and clinically indistinguishable from a soft-tissue neoplasm. The case of a spontaneous pelvic neoplasm in an otherwise healthy young man is presented and the literature reviewed regarding issues of differential diagnosis and clinical management.