Nasal Cavity: Paranasal Sinuses


Nasal Cavity: Paranasal Sinuses

Table 4.38 Small/absent sinuses




Congenital absence

Absence of frontal sinuses in 5% of population.


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.


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




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.


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.


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

Assess for Gardner syndrome.


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.


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.


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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