title: Organised haematoma of the maxillary sinus: pathophysiological differences suggesting a new aetiological hypothesis.
abstract: OBJECTIVE
  Organised haematomas of the maxillary sinus are rare, non-neoplastic, haemorrhagic lesions which can extend into the nasal cavity and/or the other paranasal sinuses. This study aimed to investigate the pathology of maxillary sinus organised haematoma, and also proposes a new aetiological hypothesis based on the observed pathology.
  
  
  METHODS
  Biopsies, computed tomography, magnetic resonance imaging and post-surgical histopathological examination of resected specimens were carried out.
  
  
  CONCLUSIONS
  Distinct pathological differences were observed between the basal and peripheral portions of organised haematomas. We propose that an organised haematoma originates from the exudation of blood components between vascular endothelial cells. As a result, the basal portion consists of aggregated, dilated vessels around the natural ostium of the maxillary sinus. In addition, pseudovessels, without endothelial cells, arise from endocapillary vessels within the haematoma. Exudation of additional blood components from the pseudovessels advances the growth of the organised haematoma.
authors.affiliation: Department of Otorhinolaryngology, Medical Center, Saitama Medical University, Japan. uraurashinjix@nifty.com
authors.forename: S
authors.initials: S
authors.lastname: Urata
authors.forename: M
authors.initials: M
authors.lastname: Ohki
authors.forename: T
authors.initials: T
authors.lastname: Tsutsumi
authors.forename: S
authors.initials: S
authors.lastname: Kikuchi
mesh_terms: D000293:Adolescent; D000369:Aged, 80 and over; D005260:Female; D006406:Hematoma / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008443:Maxillary Sinus; D010254:Paranasal Sinus Diseases / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology