Sinonasal organized hematoma: CT and MR imaging findings

BACKGROUND AND PURPOSE: Sinonasal organized hematoma (OH) is an uncommon, nonneoplastic benign condition that can be locally aggressive. The purpose of this work was to characterize the CT and MR imaging findings of sinonasal OH.MATERIALS AND METHODS: CT (n = 11) and MR (n = 10) images of 12 patients (9 men and 3 women; mean age, 41 years; range, 12–76 years) with pathologically proved sinonasal OH were retrospectively reviewed. Particular attention was put on the location, shape, size, extent, internal architecture, and enhancement pattern of the lesion and associated sinus wall change.RESULTS: The lesions were seen as an expansile (n = 9) or nonexpansile (n = 3) mass, ranging in size from 2.2 to 6.0 cm (mean, 4.2 cm), primarily involving the maxillary sinus (n = 11) or nasal cavity (n = 1) unilaterally. The ipsilateral nasal cavity was also involved in 9 of 11 maxillary sinus lesions. Smooth sinus wall erosion other than the medial maxillary sinus wall was noted in 8 lesions. The internal architecture was best displayed on T2-weighted MR images on which all of the lesions were seen as a mixture of marked heterogeneous hypointensity and isointensity, surrounded by a hypointense peripheral rim, reflecting histologic heterogeneity of the lesion composed of hemorrhage, fibrosis, and neovascularization. Marked irregular nodular, papillary, or frondlike enhancement at the areas of neovascularization was also a typical finding seen in all of the lesions.CONCLUSION: An expansile soft tissue mass, smooth sinus wall erosion, marked heterogeneous signal intensity with a hypointense peripheral rim on T2-weighted MR images, and marked irregular nodular, papillary, or frondlike enhancement are characteristic CT and MR imaging findings of sinonasal OH.

Sinonasal organized hematoma (OH) is an uncommon, nonneoplastic benign condition that can be locally aggressive. Without careful evaluation of all of the imaging features, this may be mistaken for a malignant lesion both clinically and radiologically. It most commonly affects the maxillary sinus and can result from various causes of hemorrhage with chronic hematoma formation, followed by the process of organization through fibrosis and neovascularization.^1,2 Since the first report by Ozhan et al³ in a patient with von Willebrand disease, only fewer than 40 cases have been reported in the English literature under various names, including pseudotumor,^3,4 hematoma,⁵ organized or organizing hematoma,^1,2,6–8 and hematoma-like mass of the maxillary sinus.⁹Correct preoperative diagnosis of sinonasal OH is important to avoid unnecessary extensive surgery, because this condition is curative with a simple, conservative surgical approach and rarely recurs. Although there have been a few reports on the CT findings of sinonasal OH,^1–3,5–9 which are reported to be rather nonspecific, to our knowledge, the MR imaging features have not systematically been analyzed previously. Only 2 studies had briefly mentioned the MR imaging features.^8,9 Yagisawa et al⁹ reported that masses were well demarcated from the surrounding structures and heterogeneous in signal intensity on both T1- and T2-weighted MR images. Song et al⁸ reported that the lesions appeared as isosignal intensity with a margin that had a slightly higher signal intensity on T1-weighted images and a mosaic of various signal intensities and a low signal intensity rim on T2-weighted images. The purpose of this study was to report the CT and MR imaging findings, which are believed to be characteristic for sinonasal OH.