Nasal Cavity: Paranasal Sinuses



10.1055/b-0034-87901

Nasal Cavity: Paranasal Sinuses









































Table 4.38 Small/absent sinuses

Diagnosis


Findings


Comments


Congenital absence


Absence of frontal sinuses in 5% of population.



Cretinism


Delayed/decreased pneumatisation of sinuses.



Down syndrome


Absent frontal sinuses in 90%.



Kartegener syndrome


Absent frontal sinuses.



Fibrous dysplasia


Due to overgrowth of bony wall.



Hemolytic anemia


Fig. 4.139, p. 382


Overgrowth of bony wall.



Postsurgery


Post Caldwell Luc operation.


Fig. 4.139 Hemolytic anemia. Coronal CT (bone window) shows expanded marrow cavities and diploic space causing a “hair-on-end” appearance and obliteration of sinuses in thalassemia.




























































Table 4.39 Opacification of paranasal sinuses

Diagnosis


Findings


Comments


Sinusitis—acute and chronic


Radiograph/CT/MRI: homogeneous opacification, mucosal swelling or air-fluid levels.


May see bony sclerosis or destruction if chronic.


CT important to assess for anatomic variations prior to functional endoscopic sinus surgery. Use low-dose coronal scans. Also useful to look for complications.


Trauma


Fig. 4.140


Radiograph: soft-tissue swelling, maxillary sinus opacification, ± air-fluid level.


CT: axial and coronal planes to visualize fracture.



Polyp/retention cyst


Radiograph: Opacification of single maxillary antrum. Soft-tissue mass in anterior nasopharyx on lateral view.


CT: homogeneous soft-tissue masses with smooth margins, outlined by air (e.g., mucocoele).


Sequelae of sinonasal inflammation.


Tooth bud


Radiograph: usually caused by projection and overlap.


CT: shows true ectopic tooth bud within maxillary sinus.



Osteoma


Radiograph/CT: well-defined bony density. Mainly in frontal sinuses; rarely ethmoid and maxillary.


Assess for Gardner syndrome.


Mucocoele


Fig. 4.141


CT/MRI: appearance varies with water and mucoid content. Shows peripheral enhancement, distinguishing it from neoplasm. Exhibits mass effect on adjacent structures and often expands into orbit.


Due to obstruction of sinus ostium. Most commonly frontal and ethmoid sinuses.


Primary malignancy


Fig. 4.142a, b


CT/MRI: MRI preferred due to superior soft-tissue contrast and to show intracranial extension. Need pre- and postcontrast studies.


Lymphoma, rhabdomyosarcoma, nasopharyngeal carcinoma, malignant histiocytoma.


Metastases


CT: usually neuroblastoma and is associated with soft-tissue mass.



Juvenile angiofibroma


CT: isointense or low-density mass with widening of pterygopalatine fossa and bowing of posterolateral maxillary sinus. Marked CE.


MRI: T1 hypointense, T2 hyperintense with flow voids and avid enhancement. Can show cysts, cavitation, and hemorrhage.


Benign, most common in adolescent boys.


Osteomyelitis


Radiograph/CT: sclerosis and destruction of sinus wall in setting of infection.


Usually frontal sinus.


Fibrous dysplasia


Fig. 4.143


CT: depends on fibrous vs. osseous component. Varies from radiolucent to ground-glass.


Unilocular/multilocular lesion, well-defined margin.


MRI: sharply demarcated mass, variable signal intensity, diffuse CE.



Ossifying fibroma


Fig. 4.114, p. 369


Fig. 4.138, p. 381


CT/MRI: expansile lesion with prominent areas of nonossified fibrous tissue.


Can be lytic, expansile containing calcification, and show cortical erosion.


Fig. 4.140 Coronal CT (bone window) shows comminuted fractures involving the lateral orbital wall and floor due to a gunshot wound (note bullet fragments) with opacification of the left maxillary sinus.
Fig. 4.141 A left ethmoid mucocele obstructing the ostiomeatal complex with resultant opacification of the left maxillary sinus on a coronal CT (bone window).
Fig. 4.142a, b T1-weighted coronal pre- (a) and postcontrast (b) MRI shows a T1-hypointense mass arising in the right maxillary sinus with extension into nose, orbit, and intracranially. The mass shows marked CE and is characteristic of a rhabdomyosarcoma.
Fig. 4.143 Bilateral symmetrically expanded maxillary sinuses with central fibrous component in keeping with fibrous dysplasia on an axial CT (bone window).

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Jul 12, 2020 | Posted by in PEDIATRIC IMAGING | Comments Off on Nasal Cavity: Paranasal Sinuses
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