Expansile organized maxillary sinus hematoma: MR and CT findings and review of literature.

An organized hematoma is a chronic state of fibrotic tissue surrounding a hemorrhage. A mass lesion resulting from hematoma in the maxillary sinus was first reported in 1917, and the term, "blood boil," was clinically coined from such features as encapsulated blood and locally aggressive behavior. Subsequently, others have reported lesions with a similar appearance and clinical course, and now, in Japan, blood boil is used as a clinical term for such lesions. Factors that may predispose a patient to hematoma formation vary, and the pathogenesis of the mass is still uncertain. The lesions are mainly composed of an organized hematoma, regardless of their origin. We present 2 cases of organized maxillary sinus hematomas that have unusual radiologic findings and correlate these findings with the histopathologic findings.