CT and MR imaging findings of sinonasal angiomatous polyps.

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CT and MR imaging findings of sinonasal angiomatous polyps Jing Zou a,1 , Fengyuan Man b,1 , Kai Deng c , Yuanyuan Zheng a , Dapeng Hao a,∗ , Wenjian Xu a,∗∗ a b c

Department of Radiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China Department of Radiology, Qingdao No. 4 People’s Hospital, Qingdao, Shandong, China

a r t i c l e

i n f o

Article history: Received 17 June 2013 Received in revised form 28 November 2013 Accepted 5 December 2013 Keywords: Tomography, X-ray computed Magnetic resonance imaging Paranasal sinus diseases Hemangioma Nasal polyps

a b s t r a c t Objective: To characterize the CT and MR imaging findings of patients with sinonasal angiomatous polyps (SAPs) and evaluate their respective clinical value in the diagnosis of SAP. Methods: CT and MR imaging findings of 15 patients with pathologically proven SAP were examined. Assessed image features included location, size, margin, attenuation, and change of the bony walls of the sinonasal cavity on CT, and signal intensity and enhancement pattern on MR. Results: On CT, the SAP was mostly isoattenuated with patches of slight hyperattenuation. Most lesions caused changes in the adjacent bone, including expansile remodeling (n = 8), defect or destruction (n = 7), and hyperostosis (n = 6). All lesions examined by MR showed heterogeneous isointense signal intensity on T1-weighted images and mixed obvious hyperintense and hypointense signal intensity with linear hypointense septum internally (n = 10), and hypointense peripheral rim on T2-weighted images (n = 10). Postcontrast MR images demonstrated areas of heterogeneous and marked enhancement with an unenhanced hypointense rim and septa (n = 7). Conclusions: CT and MR imaging have respective advantages in the diagnosis of SAP. Combined application of CT and MR examinations is necessary for patients with suspected SAP. © 2013 Elsevier Ireland Ltd. All rights reserved.

1. Introduction Sinonasal angiomatous polyp (SAP) is a rare benign and non-neoplastic lesion. It is primarily composed of extensively hyperplastic and dilated vessels with scanty inflammatory infiltration and abundant extracellular fibrin [1,2]. Although inflammatory sinonasal polyp (SNP) is the most common non-neoplastic sinonasal mass examined pathologically, as a special subtype SAP only accounts for 4–5% of all SNPs [1]. Simple conservative surgical excision of SAP is curative, and postoperative recurrence is rare. Therefore, correct preoperative diagnosis of SAP is important lest patients undergo unnecessary extensive surgery [3]. SAP may show similar imaging features with sinonasal masses, such as other SNP, inverted papilloma, fungus ball, capillary hemangioma, juvenile angiofibroma and some possibly malignant tumors [2,4,5]. To the best of our knowledge, there have been only a few studies describing the imaging features of SAP

∗ Corresponding author at: Department of Radiology, The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao, Shandong, China. Tel.: +86 53282911500. ∗∗ Corresponding author. Tel.: +86 53282911585. E-mail addresses: haodp [email protected] (D. Hao), [email protected] (W. Xu). 1 Both of them contributed equally and both of them are first author.

[1–8]. The purpose of this study was to report the characteristic CT and MR imaging findings of SAP in the sinonasal cavity. 2. Materials and methods 2.1. Patients The present study was approved by the institutional review board. Between July 2008 and February 2013, a total of 15 patients with pathologically proven SAP were retrospectively reviewed. The patients included five men and 10 women, age range from 12 to 81 years, with a mean age of 42.7 years. CT (n = 13) and MR (n = 10) images of these 15 patients were retrospectively reviewed. Among these 15 cases, two patients had a history of craniofacial trauma 2 days and 2 years previously, respectively. Furthermore, one patient underwent endoscopic sinus surgery to excise a nasal polyp 20 years previously, and there had been massive bleeding from the ipsilateral nasal cavity 5 years previously without apparent cause. The duration of symptoms before diagnosis ranged from 20 days to 20 years (median, 12 months). All 15 patients underwent surgical excision of SAP by endoscopic sinus surgery. 2.2. Imaging techniques Among the 15 patients, CT scanning was performed in 13 patients and MR imaging in 10 patients. Eight patients underwent

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Please cite this article in press as: Zou J, et al. CT and MR imaging findings of sinonasal angiomatous polyps. Eur J Radiol (2013), http://dx.doi.org/10.1016/j.ejrad.2013.12.002

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Fig. 1. Axial CT scan with a bone algorithm (a) shows an expansile mass (asterisk) centered in the right maxillary sinus. Expansile remodeling and thinning of the medial wall is observed (arrow). Axial CT scan with a soft tissue algorithm (b) shows a soft tissue mass (asterisk) isoattenuating to the masseter muscle with additional patches of slight hyperattenuation. Axial T1-weighted image (c) depicts heterogeneous isointense signal intensity with additional patches of interspersed hyperintensity and linear shadow of hypointensity on the mass (asterisk). Axial fat-suppressed T2-weighted image (d) demonstrates a well-defined lesion, which is markedly heterogeneous with linear hypointense septum internally and hypointense peripheral rim surrounding the lesion (asterisk). The bright signal intensity (arrow) due to obstructive sinusitis is demonstrated. Photomicrograph (e) shows that the lesion consists mostly of hemorrhage and necrosis, accompanied by extravasated fibrin and inflamed columnar epithelium (H&E, 100).

both CT and MR examinations. Seven patients underwent postcontrast T1-weighted imaging. CT scans were obtained using a standard CT protocol for the paranasal sinuses. Thirteen patients underwent 2.5-mm-thick axial CT scanning with a bone algorithm and all images were reformatted with a soft tissue algorithm without the use of contrast media. In these patients, direct (n = 10) or reformatted (n = 3) coronal images were also obtained. MR examinations were performed using a 1.5 T MR scanner (n = 5) (Signa Advantage Horizon; GE Medical Systems, Milwaukee, WI) or a 3.0 T MR scanner (n = 5) (Signa HDx; GE Medical Systems) with an 8-channel head coil. In these patients, precontrast T1-weighted spin-echo images (n = 10) and T2-weighted fast spinecho images with fat saturation (n = 7) or short TI inversion recovery (n = 3) were obtained, followed by contrast-enhanced, T1-weighted

spin-echo images with fat saturation after the intravenous injection of 0.1 mmol/kg of gadolinium dimeglumine in seven patients. Images were obtained in at least two planes with 3 mm section thickness and 1 mm intersection gap. 2.3. Imaging analysis Two experienced head and neck radiologists retrospectively reviewed all the CT and MR images in consensus. The CT and MR imaging characteristics were analyzed with particular attention to the location, shape (expansile or nonexpansile), size, margin, attenuation on precontrast CT, changes of the bony walls of the sinonasal cavity on bone CT, signal intensity on precontrast MR, and enhancement pattern on contrast-enhanced MR. The attenuation or signal intensity of the lesion was compared with that of the masseter




Fig. 2. Axial CT scan with a soft tissue algorithm (a) shows an irregularly shaped mass in the left maxillary sinus and nasal cavity, which extends to the nasopharynx through choana (asterisk). Coronal CT in a bone algorithm (b) shows an expansile mass located in the enlarged sinus cavity (arrow). The margin is well defined, and the nasal septum is compressed and deformed. There is a large defect in the medial maxillary sinus wall (arrowheads).

muscle. The location of each lesion, whether in the maxillary sinus or/and in the nasal cavity, was confirmed according to the site of the main body of the lesion. The size of each lesion was measured at the greatest diameter of the mass. The margin of each lesion was classified as well-defined or ill-defined. On postcontrast MR images, the degree of enhancement was also subjectively assessed as mild enhancement (less than or equal to that of the masseter muscle) or marked enhancement (greater than that of the masseter muscle). 3. Results The symptoms of the patients were nasal obstruction in 80.0% (12/15), epistaxis in 53.3% (8/15), rhinorrhea (n = 4), headache (n = 3), facial numbness (n = 2), visual acuity reduction (n = 1), hyposmia (n = 3), and syrigmus (n = 2). Histopathological examinations showed most of the central areas of the lesion were composed of hemorrhage with extensive hyperplastic and dilated thin-walled blood vessels, fibrosis, and thrombus formation, and areas of focal inflammation. The central areas were surrounded by hemosiderin-laden macrophages, associated with recent hemorrhages (Figs. 1e and 4d). Grossly, the SAP was seen as a relatively well-circumscribed, lobulated and necrotic mass with a purple or dark red surface that bled easily when touched lightly. On sectioning, the cut surfaces were firm, alternating with yellow-brown and hemorrhagic necrotic zones that showed cystic degeneration. Moreover, in eight lesions, SAP was found to accompany an inflammatory polyp of the sinonasal cavity.

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The CT and MR imaging features of the 15 patients with SAP are summarized in Table 1. Eight SAPs occurred in the left side and seven in the right side. Thirteen lesions were located in the maxillary sinus and nasal cavity. Two lesions were confined to the nasal cavity. Of these, seven cases extended to the choana and nasopharynx (Fig. 2). On CT and MR images, these lesions were seen as an expansile mass in 10 patients (Figs. 1a–d, 3, and 4a–c) and nonexpansile mass in five patients. The size of the lesions ranged from 10.4 mm to 62.6 mm in greatest diameter, with a mean of 40.3 mm. Thirteen of 15 (86.7%) lesions displayed well-defined margins and two of 15 (13.3%) lesions were ill-defined (Fig. 3b). On CT images, the masses were heterogeneous. The lesions had a soft tissue density and filled the sinonasal cavity. Compared with the masseter muscle, the mass was mostly isoattenuated in all patients, with additional patches of slight hyperattenuation in 11 patients (Figs. 1b and 2a). Calcification was not found in any case. Most lesions (12/13) caused changes in the adjacent bone, including expansile remodeling accompanied by thinning of the bony wall (n = 8, Fig. 1a), defect or destruction of adjacent bones (n = 7, Fig. 3a), and hyperostosis of the sinonasal walls (n = 6, Fig. 3c). The most common site of maxillary wall with expansile remodeling and thinning was the medial wall (n = 7), followed by the nasal septum (n = 4) and the posterior lateral wall (n = 2). The defect of the bony wall also could be seen in the medial wall (n = 5), lateral wall (n = 3), posterior wall (n = 1), and the medial wall of the orbit (n = 1). Hyperostosis was seen along the posterior lateral wall (n = 5) and the anterior wall (n = 3). All of the 10 lesions examined by MR mostly showed heterogeneous isointense signal intensity (n = 10) on T1-weighted images, with additional points or patches of interspersed slight hyperintensity (n = 10) and linear shadow of hypointensity (n = 9) (Figs. 1c and 4a). In contrast, all of the lesions showed markedly heterogeneous, mixed hyperintense and hypointense signal intensity on T2-weighted images (n = 10), with linear hypointense septum internally (n = 10) and hypointense peripheral rim surrounding the lesion (n = 10) (Figs. 1d and 4b). Postcontrast MR images demonstrated areas of heterogeneous and marked enhancement (n = 7) in all of the lesions with an unenhanced hypointense rim and septa (n = 7) (Fig. 4c). Obstructive sinusitis was observed in all patients (n = 10) in varying degrees (Figs. 1d and 4b). 4. Discussion There are numerous descriptions of SAP in the literature, including organized or organizing hematoma [3,7–14], cavernous hemangioma [15–17], hemangioma [18,19], hematoma-like mass of the antrum [20], pseudotumor [21], hemorrhage necrotic polyp, and angioectatic or angiomatous polyp [1,2,4–6,22,23]. Study and comparison of these seven terms shows that they all share the same clinical, pathological, and imaging features. The present study uses the term “angiomatous polyp” because it reflects the fact that the lesion is not a real tumor and that the mass is characteristically filled with clusters of irregularly shaped, dilated thin-walled vessels and extensive vascular proliferation. The pathogenesis of SAP has not been elucidated; however, many hypotheses have been proposed. At present, there are two prevailing opinions. One hypothesis is based on the presence of nasal polyps. The polyps are usually located near the sinus ostia and protrude through the sinus ostium into the adjacent cavity. Because of the particular anatomical conditions, the polyp pedicle is subject to significant vascular compromise. Accordingly, the compression of the feeder vessels causes stasis, edema, and ischemia of the polyp. This leads to venous infarction followed by neovascularization and fibrosis of the polyp, which then evolves into the final SAP [23].


1/54Y/F 2/20Y/F

3/33Y/M

6/55Y/F

7/30Y/M

8/31Y/M

9/16Y/F

10/24Y/F 11/55Y/M 12/12Y/F

13/65Y/F

14/73Y/F

15/60Y/M

Nasal obstruction and rhinorrhea with epistaxis for 1 year Nasal obstruction for 2 months Epistaxis and hyposmia for 6 months

Nasal obstruction and epistaxis for 20 days with craniofacial trauma before 2 years Headache with rhinorrhea and nasal obstruction accompany with hyposmia for more than 5 years Headache with epistaxis for 2 days after craniofacial trauma Nasal obstruction for 1 year and visual acuity reduction for 1 month Nasal obstruction for 7 months Rhinorrhea with epistaxis for 2.5 years Nasal obstruction accompany with hyposmia and syrigmus for 1 month Nasal obstruction and epistaxis for 20 years and headache with facial numbness for 10 years and underwent sinus surgery before 20 years Nasal obstruction with rhinorrhea for 1 month and epistaxis and syrigmus for more than 10 days Nasal obstruction and epistaxis for 1 year

Shape/marge

CT

MR imaging

Accompany with inflammatory polyp

Attenuationa

Bone change

T1-weighted imagea

T2-weighted imagea

Enhancement degreeb

Nonexpansile/welldefined Expansile/welldefined

ISO.

Hyperostosis

–

–

–

Yes

ISO. with patches of HYP.

Isointense

Heterogeneous hyperintense

Marked heterogeneous

No

Yes/yes

Nonexpansile/illdefined


Expansile remodeling and defect Hyperostosis and defect

Isointense



No

No/yes

Expansile/welldefined Expansile/welldefined

–

–

Isointense


No


Isointense


No

Yes/no

Expansile/illdefined


–

–

–

No

Yes/yes

Expansile/welldefined


Isointense


–

Yes

No/yes


–

Hyperostosis and expansile remodeling and defect Hyperostosis and expansile remodeling and defect Hyperostosis and expansile remodeling and defect –

Heterogeneous hyperintense Heterogeneous hyperintense

Isointense



No

Yes/no



–

–

–

Yes

Yes/yes

Expansile/welldefined Expansile/welldefined Nonexpansile/welldefined

ISO. with patches of HYP. ISO. with patches of HYP. ISO.

Yes/yes


Yes/yes

Yes/yes

Yes/no Yes/yes

Yes/yes

Yes/yes Yes/yes

Expansile remodeling and defect Expansile remodeling Defect

–

–

–

Yes

Isointense

–

Yes

None

–

Heterogeneous hyperintense –

–

Yes


Expansile remodeling

Isointense


–

Yes



Expansile remodeling

Isointense



Yes

nonexpansile/welldefined


Hyperostosis

Isointense



No

Note: ISO., isoattenuation; HYP., hyperattenuation. a Compared with the attenuation and signal intensity of the masseter muscle. b Compared with the enhancement of the masseter muscle.

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5/81Y/F

Nasal obstruction and facial numbness for 15 days Nasal obstruction for 1 year

CT/MR image

ARTICLE IN PRESS

4/42Y/F

Chief symptom

G Model

Patient/age (year)/sex

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Table 1 Clinical and imaging findings in 15 patients with SAP.



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Fig. 3. Coronal CT scan with bone algorithm (a) shows a soft tissue mass in the left maxillary sinus, which causes a bone defect of the anterior wall (arrow). Coronal CT scan with soft tissue algorithm (b) shows the lesion extends to the fat space and displays an ill-defined margin (arrow). Axial CT scan with bone algorithm (c) demonstrates hyperostosis in the posterior lateral wall of the left maxillary sinus (arrows).

Another hypothesis is based on the formation of hematoma in the sinus antrum [3,7,8]. The hematoma develops initially from the accumulation of blood in the sinus antrum resulting from various causes, such as trauma, surgery, bleeding diatheses, and the loss of mechanical integrity of an arterial branch, as seen in a ruptured aneurysm or inflammatory erosion of an arterial wall [7,12–14]. The blood remains in the sinus antrum because of poor ventilation and drainage conditions, especially in the maxillary sinus. As is known, SAP occurs most frequently in the maxillary sinus, the largest paranasal sinus. These allow conditions of negative pressure and decreased ventilation [7]. Persistent negative pressure and decreased ventilation lead to difficulties in expelling fresh blood from the maxillary sinus, and subsequently organization and fibrous degeneration of hematoma ensue. Reactive and reparative changes with neovascularization lead to the eventual formation of SAP. This process accounts for the progressive expansion and local bony destruction associated with SAP [3,7,8,13]. Based on the results of the present study, the two hypotheses are both reasonable. Of the 15 cases examined, most lesions (n = 13) were located near the sinus ostium and often involved the ipsilateral nasal cavity and maxillary sinus through the ostium and extended toward the choana and nasopharynx (n = 7). Furthermore, eight cases were associated with the inflammatory polyps proven by pathological reports and/or operative notes. Given these facts, the first hypothesis is reasonable in some cases. However, some cases are also consistent with the latter hypothesis. Three cases had a history of previous head and neck surgery or a history of craniofacial trauma. Six cases had a history of frequent epistaxis. Moreover, the most lesions (n = 13) were located in the maxillary sinus, and expansion (n = 10) and local bony destruction (n = 7) were also frequent. A wide age range of patients has been reported, from 11 to 81 years [4,5,14,20,21,24]. In the present study, patients’ age ranged

from 12 to 81 years (median, 42.7 years), and there was a preponderance of women, with a male-to-female ratio of 1:2. As in the literature [6,7,13,20], patients often presented with nasal obstruction (n = 12) and epistaxis (n = 8), because gradual enlargement of the lesion displaced the adjacent bony structures and caused inflammatory infiltration of stroma, which eroded the hyperplastic and thin-walled vessels. Reports on of SAP clarified that CT findings lacked specificity for SAP identification [4,5,7]. The typical appearance includes an expansile mass causing bulge or destruction of the bony wall and heterogeneous isoattenuation on precontrast CT scans. The presence of attenuation in the present study is in accordance with the characteristics previously mentioned. In the present study, most of the lesions (n = 12) caused changes in the adjacent bone, including expansile remodeling and thinning, defect or destruction of adjacent bones, and hyperostosis of the sinonasal walls. Expansile remodeling and thinning of adjacent bones was the most common change (n = 8), and may indicate a long growth process and benign growth pattern. In seven cases, defect of the bony wall could also be seen, which was caused by increasing pressure and/or bone resorption. Hyperostosis (n = 6) may be related to chronic obstructive sinus inflammatory reaction. It is difficult to make accurate diagnoses based only on the CT features, such as the large soft tissue mass with heterogeneous density and the associated bone destruction [1,4]. However, the masses are well defined and do not invade the peripheral soft tissue on CT, which is associated with the non-neoplastic growth pattern of SAP. In spite of CT imaging lacking specificity for SAP, it was superior to MR imaging for demonstrating bone changes associated with the lesion. Compared with the CT findings, the SAP lesion has a characteristic appearance on MR images. According to the literature and the present study, the typical imaging features of SAP on


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Fig. 4. Axial T1-weighted MR image (a) shows that the lesion is mostly isointense compared to the masseter muscle interspersed with points of hyperintensity (asterisk). Axial, short TI inversion recovery MR image (b) shows the marked heterogeneity of the lesion with a mix of hypointense, and marked hyperintense signals (asterisk). The dark peripheral rim surrounding the lesion is also well demonstrated. The curvilinear hyperintensity area around the mass indicates obstructive sinusitis. Postcontrast axial, fat-suppressed, T1-weighted MR image (c) shows heterogeneous and marked enhancement (asterisk) in most regions of the lesion with an unenhanced hypointense rim and septa. Photomicrograph (d) shows that the lesion consists of hemorrhage, extravasated fibrin, inflamed cells and scattered hemosiderin-laden macrophages (H&E, 100×).

MR images are as follows: (i) expansive soft tissue mass, (ii) well-defined margin, (iii) blockage of ostium and secondary obstruction, (iv) extension into the choana and nasopharynx, (v) heterogeneous isointense signal intensity with interspersed slight hyperintensity on T1-weighted imaging, and (vi) markedly heterogeneous, obvious hyperintense with hypointense linear septum internally and peripheral rim surrounding the lesion. Remarkably, the hypointense peripheral rim around the mass is a very specific contribution to the correct diagnosis of SAP. The postcontrast MR images of SAP also demonstrated a characteristic appearance with areas of heterogeneous and marked enhancement with unenhanced hypointense rims and septa. In the present study, MR imaging showed the margin and extent of the mass more clearly and more precisely than CT imaging, as reported by Kim et al. [3]. The hydrops of the adjacent paranasal sinuses caused by secondary obstruction and inflammation can be differentiated easily from the lesion on MR images, especially on T2-weighted images. However, it is difficult to distinguish between the main lesion and sinus inflammation on CT, which often results in overestimating the size of the lesion. Furthermore, due to the higher soft tissue contrast resolution, MR imaging is superior to CT for determining the internal characteristics of the lesion with various signal intensities on T1- and T2-weighted Images 3. Although an exact 1:1 MR-pathologic correlation is not possible because most lesions are removed in pieces and not en bloc, the heterogeneous signal intensity seen on MR images reflects the various components contained within the lesion, such as hemorrhage in various stages, fibrosis, and various amounts of vascular proliferation [3,24]. Postcontrast MR imaging can provide valuable information about the

blood supply of the mass and the integrity of vessel walls to predict whether a lesion is benign or malignant. As suggested by Lee et al. [7], the areas with enhancement represent the areas of prominent vascular proliferation. Based on previous experience, the appearance of SAP on CT may cause the radiologist to misdiagnose the mass as malignant. Bone erosion can also occur in other benign lesions, such as other inflammatory nasal polyps, cholesterol granuloma, fungus ball, inverted papilloma and capillary hemangioma [4,7,14,24]. The radiologist should not presume that a lesion is malignant simply relying on a defect in the bone on CT images. Contrast enhancement examination is extremely useful, because inflammatory polyp, cholesterol granuloma, and fungus ball are not usually enhanced. Inverted papilloma primarily involves the nasal cavity and reveals a characteristic convoluted cerebriform pattern on both T2-weighted imaging and contrast-enhanced T1-weighted imaging [25]. Capillary hemangioma is difficult to differentiate from SAP both clinically and radiologically. Tubular flow-void signal intensity on both T2-weighted imaging and contrast-enhanced T1-weighted imaging may be a noteworthy contribution to differential diagnosis [4,26]. Malignant tumors demonstrate frank bony destruction, rather than a clearly defined defect of the sinus walls, associated with adjacent tissue invasion, which results in indistinguishable fat space around the lesion [7]. For radiologists inexperienced in head and neck pathology, SAP may be misdiagnosed as juvenile nasopharyngeal angiofibroma. The main identifications of juvenile nasopharyngeal angiofibroma as follows: (i) affecting young males, (ii) widening the pterygopalatine fossa with bowing of the posterior wall of the maxillary sinus, (iii) multiple flow-void channelson




MRI and (iv) marked enhancement after Gd-DTPA administration [2,27]. 5. Conclusions Correct preoperative diagnosis is important for determining therapeutic schedules, because SAP is usually curative with complete surgical resection by endoscopic sinus surgery. CT and MR imaging have respective advantages in the diagnosis of SAP. Preoperative CT images that show the changes in adjacent bones can provide an accurate basis for the determination of the surgical scope. Preoperative MR images that show the characteristic appearance in signal intensity can provide an accurate diagnosis of SAP. Therefore, combined application of CT and MR examinations is necessary for patients with suspected SAP. Moreover, the characteristic appearance on postcontrast MR images of SAP also provides the basis for qualitative diagnosis and preoperative preparation. References [1] Yfantis HG, Drachenberg CB, Gray W, Papadimitriou JC. Angiectatic nasal polyps that clinically simulate a malignant process: report of 2 cases and review of the literature. Archives of Pathology & Laboratory Medicine 2000;124(3):406–10. [2] Sheahan P, Crotty PL, Hamilton S, Colreavy M, McShane D. Infarcted angiomatous nasal polyps. European Archives of Otorhinolaryngology 2005;262(3):225–30. [3] Kim EY, Kim HJ, Chung SK, et al. Sinonasal organized hematoma: CT and MR imaging findings. AJNR American Journal of Neuroradiology 2008;29(6):1204–8. [4] Wang YZ, Yang BT, Wang ZC, Song L, Xian JF. MR evaluation of sinonasal angiomatous polyp. AJNR American Journal of Neuroradiology 2012;33(4):767–72. [5] Dai LB, Zhou SH, Ruan LX, Zheng ZJ. Correlation of computed tomography with pathological features in angiomatous nasal polyps. PLOS ONE 2012;7(12):e53306. [6] De Vuysere S, Hermans R, Marchal G. Sinochoanal polyp and its variant, the angiomatous polyp: MRI findings. European Radiology 2001;11(1):55–8. [7] Lee HK, Smoker WR, Lee BJ, Kim SJ, Cho KJ. Organized hematoma of the maxillary sinus: CT findings. AJR American Journal of Roentgenology 2007;188(4):W370–3. [8] Nishiguchi T, Nakamura A, Mochizuki K, Tokuhara Y, Yamane H, Inoue Y. Expansile organized maxillary sinus hematoma: MR and CT findings and review of literature. AJNR American Journal of Neuroradiology 2007;28(7):1375–7.

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[9] Chiang TY, Chen MK. Organized hematoma of maxillary sinus mimicking malignant neoplasm in a patient following chemoradiotherapy. Journal of Otolaryngology – Head & Neck Surgery 2008;37(2):E42–5. [10] Suzuki H, Inaba T, Hiraki N, et al. Endoscopic sinus surgery for the treatment of organized hematoma of the maxillary sinus. Kurume Medical Journal 2008;55(3–4):37–41. [11] Shen KJ, Som PM, Teng MS. Radiology quiz case 2. Organized hematoma of the maxillary sinus. Archives of Otolaryngology – Head & Neck Surgery 2007;133(4):408, 10. [12] Yoon TM, Kim JH, Cho YB. Three cases of organized hematoma of the maxillary sinus. European Archives of Otorhinolaryngology 2006;263(9):823–6. [13] Lee BJ, Park HJ, Heo SC. Organized hematoma of the maxillary sinus. Acta otoLaryngologica 2003;123(7):869–72. [14] Unlu HH, Mutlu C, Ayhan S, Tarhan S. Organized hematoma of the maxillary sinus mimicking tumor. Auris, Nasus, Larynx 2001;28(3):253–5. [15] Kim HJ, Kim JH, Hwang EG. Bone erosion caused by sinonasal cavernous hemangioma: CT findings in two patients. AJNR American Journal of Neuroradiology 1995;16(5):1176–8. [16] Jammal H, Barakat F, Hadi U. Maxillary sinus cavernous hemangioma: a rare entity. Acta oto-Laryngologica 2004;124(3):331–3. [17] Mussak E, Lin J, Prasad M. Cavernous hemangioma of the maxillary sinus with bone erosion. Ear, Nose, & Throat Journal 2007;86(9):565–6. [18] Song CE, Cho JH, Kim SY, Kim SW, Kim BG, Kang JM. Endoscopic resection of haemangiomas in the sinonasal cavity. Journal of Laryngology and Otology 2009;123(8):868–72. [19] Raboso E, Rosell A, Plaza G, Martinez-Vidal A. Haemangioma of the maxillary sinus. Journal of Laryngology and Otology 1997;111(7):638–40. [20] Yagisawa M, Ishitoya J, Tsukuda M. Hematoma-like mass of the maxillary sinus. Acta oto-Laryngologica 2006;126(3):277–81. [21] Ozhan S, Arac M, Isik S, Oznur II, Atilla S, Kemaloglu Y. Pseudotumor of the maxillary sinus in a patient with von Willebrand’s disease. AJR American Journal of Roentgenology 1996;166(4):950–1. [22] Ceylan A, Asal K, Celenk F, Uslu S. An angiomatous nasal polyp: a very rare variant of sinochoanal nasal polyps. B-ENT 2007;3(3):145–7. [23] Batsakis JG, Sneige N. Choanal and angiomatous polyps of the sinonasal tract. Annals of Otology, Rhinology, and Laryngology 1992;101(7):623–5. [24] Song HM, Jang YJ, Chung YS, Lee BJ. Organizing hematoma of the maxillary sinus. Otolaryngology – Head and Neck Surgery: Official Journal of American Academy of Otolaryngology – Head and Neck Surgery 2007;136(4):616– 20. [25] Ojiri H, Ujita M, Tada S, Fukuda K. Potentially distinctive features of sinonasal inverted papilloma on MR imaging. AJR American Journal of Roentgenology 2000;175(2):465–8. [26] Lee DG, Lee SK, Chang HW, et al. CT features of lobular capillary hemangioma of the nasal cavity. AJNR American Journal of Neuroradiology 2010;31(4):749–54. [27] Gomaa MA, Hammad MS, Abdelmoghny A, Elsherif AM, Tawfik HM. Magnetic resonance imaging versus computed tomography and different imaging modalities in evaluation of sinonasal neoplasms diagnosed by histopathology. Clinical Medicine Insights: Ear, Nose Throat 2013;26(6):9–15.


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Mycetoma: comparison of MR imaging with CT.

MR imaging findings of trigger thumb.

Pituitary adenomas: findings of postoperative MR imaging.

Macronodular tuberculoma of the liver: CT and MR findings.