|Year : 2018 | Volume
| Issue : 2 | Page : 42-44
An unexpected finding in the frontal sinus: Cholesterol granuloma
Laura L Wuyts1, Alexandra N Boogers2, Lieve R Vanwalleghem3, Jan W Casselman4
1 Department of Radiology, Gza Hospitals, Wilrijk, Belgium
2 Department of Neurology, AZ Sint-Jan Brugge-Oostende AV. Ruddershove 10, 8000 Brugge, Belgium
3 Department of Pathology, AZ Sint-Jan Brugge-Oostende AV. Ruddershove 10, 8000 Brugge, Belgium
4 Department of Radiology, Gza Hospitals, Wilrijk; Department of Radiology, AZ Sint-Jan Brugge-Oostende AV. Ruddershove 10, 8000 Brugge, Department of Radiology, University of Ghent, St. Pietersnieuwstraat 33 9000 Gent, Belgium
|Date of Web Publication||13-Aug-2018|
Laura L Wuyts
Department of Radiology, Gza Hospitals, Oosterveldlaan 24, 2610 Wilrijk
Source of Support: None, Conflict of Interest: None
There is a broad differential diagnosis for patients presenting with an expansile mass lesion in the frontal sinus on computed tomography. Due to the composition of granulation tissue, a cholesterol granuloma exhibits unique signal characteristics and should be considered when an expansive paranasal sinus mass with high signal intensity on both T1- and T2-weighted images is seen. A cholesterol granuloma is a benign tumor, and small lesions are mostly harmless. However, large cholesterol granuloma may cause severe morbidity and even mortality if unrecognized, by extension through the orbit and in the anterior cranial fossa, emphasizing the importance of early diagnosis and resection. We present the case of a young male with an expanding mass under the right eyebrow, proved to be a cholesterol granuloma on pathological examination. The differential diagnosis and the distinct radiological features of this rare entity are discussed.
Keywords: Cholesterol cyst, cholesterol granuloma, frontal sinus, frontal sinus mass, paranasal sinus mass
|How to cite this article:|
Wuyts LL, Boogers AN, Vanwalleghem LR, Casselman JW. An unexpected finding in the frontal sinus: Cholesterol granuloma. J Oral Maxillofac Radiol 2018;6:42-4
|How to cite this URL:|
Wuyts LL, Boogers AN, Vanwalleghem LR, Casselman JW. An unexpected finding in the frontal sinus: Cholesterol granuloma. J Oral Maxillofac Radiol [serial online] 2018 [cited 2019 Jun 17];6:42-4. Available from: http://www.joomr.org/text.asp?2018/6/2/42/238932
| Introduction|| |
Cholesterol granulomas are often found in the temporal bone. They are less common in the orbit and rare in the paranasal sinuses. In English literature, <200 cases of cholesterol granulomas in paranasal sinuses were reported.,, Occurrence in the frontal sinuses is even more unusual: a systematic review in 2013 yielded around 81 (orbito) frontal cases in literature. Bone destruction and orbital complications may occur in large cholesterol granuloma, emphasizing the importance of early diagnosis and resection. The purpose of this case report is to make a radiologist aware of the specific imaging characteristics to help achieve the accurate diagnoses, even in this unusual location, since the appropriate treatment relies on it. We present a case where the cholesterol granuloma was excised before the development of serious morbidity.
| Case Report|| |
A 34-year-old male with no prior history except for hypercholesterolemia presented with the complaints of an expansile mass under his right eyebrow since a few weeks. He had a blocked right nose since a couple of months. Inspection showed a slight lowering of the medial corner of the right eyebrow. Palpation revealed a small mass in the upper medial corner of the right orbit. The mass had a spherical shape with a diameter of approximately 2 cm, was hard, and could not be moved.
A computed tomography (CT) scan of the head was performed and showed an enlargement and opacification of the right frontal sinus [Figure 1]a. Anteriorly, the adjacent bone is thinned and almost dehiscent by the expansive lesion. The lesion has a density of 45 Hounsfield Units and dimensions of 15 mm × 21 mm × 19 mm. There is no extension into the anterior cranial fossa, right orbit, or ethmoid cells. Magnetic resonance (MR) imaging was performed for characterization of the soft-tissue component. T2-weighted images show a high internal signal intensity and a dark, hypointense rim of the lesion in the right frontal sinus [Figure 1]b. Also, on T1-weighted Dixon images, a high internal signal intensity is seen, with intermediate signal of the surrounding tissue [Figure 1]c. After administration of gadolinium intravenously, only a faint peripheral enhancement is discernible [Figure 1]d. The images of the brain parenchyma show no abnormalities.
|Figure 1: (a) Axial head computed tomography demonstration enlargement of the right frontal sinus with thinned and almost dehiscent overlying bone (arrowheads), without breakthrough of the cortex. (b) Axial T2-weighted image with a high internal signal intensity (arrow) and surrounding hypointense rim (asterisk). (c) Axial T1-weighted image demonstrating high internal signal intensity, with intermediate signal of surrounding tissue. (d) Axial gadolinium-enhanced T1-weighted image shows faint peripheral enhancement.|
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Excision of the lesion was performed by an oral and maxillofacial surgeon. With a bicoronal incision, the skin was incised and pulled forward, together with the frontal muscle. Only a very thin layer of bone was covering the mass. The bone was easily opened with a small drill, and the lesion could smoothly be scooped out of the frontal bone. Macroscopically the mass was round with multiple small bubbles, resembling a dermoid cyst. With a titanium grid, the frontal sinus was closed again. Pathological examination indicated the lesion to be a cholesterol granuloma based on the diffuse infiltration of cholesterol spicules and histiocytes [Figure 2]. CT imaging and MR imaging 6 months after surgery show normal postoperative findings, i.e., fibrous formation without any sign of recurrence of the tumor.
|Figure 2: Microscopic image of the cholesterol granuloma. Fibrous connective tissue with multiple cholesterol spicules (triangle) and histiocytes (asterisk). The surgical specimen was fixed with 4% buffered formaldehyde and stained with hematoxylin and eosin. The box indicates a length of 50 μm.|
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| Discussion|| |
Cholesterol granulomas are most often found in the mastoid portion, middle ear, and petrous apex of the temporal bone. Less than 200 cases of cholesterol granulomas in paranasal sinuses were reported in English literature.,, Most of them are located in the frontal sinus. The maxillary sinus and the ethmoid sinus were the second and third most prevalent location., The prevalence in men is 5.6 times higher than in women, with middle-aged men being more affected. Precipitating factor can be previous trauma or surgery, recurrent sinusitis leading to focal bleeding, outflow obstruction, and mucociliary dysfunction.,
Presenting symptoms are nonspecific and include headache, facial or orbital pain, nasal obstruction or rhinorrhea, epistaxis, proptosis, and diplopia. CT imaging demonstrates the sinus opacification and expansion by the cystic lesion. On bone CT, cortical thinning and erosion of adjacent bony trabeculae can be seen. The cholesterol content results in the typical high signal intensity of the lesion on both T1- and T2-weighted images. A surrounding hypointense rim is due to hemosiderin deposition in the margins of the cyst. On imaging after contrast, only faint peripheral enhancement is seen. Cholesterol granuloma exhibits low signal intensity on diffusion-weighted images.
Although a cholesterol granuloma is a benign entity, a large lesion may cause the thinned overlying bone to be dehiscent. Extension through the orbit and in the anterior cranial fossa causes morbidity and potential mortality, emphasizing the importance of early diagnosis and resection.
In the differential diagnosis of an opacified and expanded sinus, we include a mucocele, one of the most common benign entities in the frontal sinus, with smooth remodeling of the bony walls. However, a mucocele with high water content has typically a low signal intensity on T1-weighted images and high signal intensity on T2-weighted images.
Another expansile lesion that may occur in the frontal sinus is an ossifying fibroma. This benign, fibro-osseous neoplasm has a fibrous central area with soft-tissue density and a surrounding rim of mature bone. On T1-weighted images, intermediate-to-low signal intensity is seen and mixed areas of low and high signal on T2-weighted images.
Osteoma, the most common benign sinus neoplasm, has different imaging characteristics since it consists of dense lamellar bone, typically without a soft-tissue component and with low signal intensities on both T1- and T2-weighted images.
There is no ground-glass opacification or cystic areas that may suggest fibrous dysplasia. In case of fibrous dysplasia, heterogeneous signal is seen on T1- and T2-weighted images, and in active fibrous dysplasia, there is a strong enhancement after administration of contrast. Moreover, fibrous dysplasia has a predilection for the skull base rather than sinuses.
| Conclusion|| |
A cholesterol granuloma is a benign tumor, but expansion of the tumor can have severe consequences. Early detection and resection is a key to prevent morbidity and mortality. Resection used to be done with open surgery, but lately, endoscopic procedures are preferred if the lesion can be reached endoscopically.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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