Head & NeckParanasal Sinuses & Nose

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Paranasal Sinuses & Nosea) Acute Sinusitisb) Mucous Retention Cystc) Polypsd) Destructive Sinusitise) Fungal Sinusitisf) Mucoceleg) Inverted Papillomah) Benign Tumorsi) Malignant Tumorsj) Small or Absent Sinusesh) Opaque Maxillary Antrumk) Mass in the Maxillary Antrum

a) Acute Sinusitis :1-Incidence2-Types3-Radiographic Features

1-Incidence :-Frequency of involvement : maxillary >

ethmoidal , frontal > sphenoidal sinus-Sinusitis is frequently associated with upper

respiratory tract infections due to occlusion of draining ostia

2-Types :a) Infectious sinusitis :-Acute-Subacute-Chronicb) Noninfectious (allergic)c) Dental infection and sinusitis (20% maxillary

antrum)

3-Radiographic Features :-Opacified sinus partial or complete-Mucosal thickening-Air fluid levels-Chronic sinusitis : mucosal hyperplasia ,

pseudopolyps & hyperostosis of bone

-Complications :1-Erosion through bone :-Subperiosteal abscess-Frontal sinus superficially (Pott puffy tumor), CT typically

demonstrates an opacified frontal sinus with stranding and swelling of the overlying scalp, bone algorithm will often demonstrate a defect in the anterior wall of the sinus, contrast may demonstrate a focal abscess, and may also allow intracranial complications to be better delineated

-Frontal or ethmoidal sinuses into orbit2-Dural venous sinus thrombosis3-Intracranial extension :-Meningitis-Subdural empyema-Cerebral abscess formation-Focal cerebritis

Sinusitis with orbital subperiosteal abscess

Sinusitis with orbital subperiosteal abscess

Pott puffy tumor: a) Axial and b) sagittal CT+C in a soft tissue window showing opacification of the frontal sinus with heterogeneous material (*) and a subperiosteal abscess (white arrow) due to frontal sinusitis, note the small subdural fluid collection (black arrow) indicating subdural empyema, c) Sagittal T1+C in another patient showing a large subperiosteal abscess (long arrow), and a large extra-axial empyema (short arrow), d) Axial CT image in a bone window in the same patient showing erosion of the tabula externa (arrow) adjacent to the soft tissue mass, indicative of osteomyelitis of the frontal bone

Pott puffy tumor

Pott puffy tumor, abnormal tissue in the frontal sinus (yellow arrow), subperiosteal abscess (red arrow) and the fluid-fluid level (green arrow) in the large intracranial lesion which has ring enhancement, all abnormalities are continuous meaning there is frontal bony destruction, the restricted diffusion also supports the diagnosis of brain abscess

Preseptal abscess, CT+C in soft tissue window showing a heterogeneous collection in the right eyelid with rim-enhancement (*) indicative of preseptal abscess; note the adjacent opacification of the ethmoid sinus (E) indicative of ethmoiditis

Orbital cellulitis, CT+C in a soft tissue window showing opacification of the left ethmoid sinuses (E), infiltration and thickening of the eyelid (short white arrow) indicative of preseptal cellulitis, and infiltration of the postseptal/orbital fat (long white arrow) adjacent to the lamina papyracea (black arrow) indicative of orbital cellulitis and possibly early subperiosteal abscess

Subperiosteal abscess, (a) axial CT+C in a soft tissue window showing opacified ethmoid sinuses; preseptal cellulitis (*); and a small crescent shaped soft tissue mass (arrow) adjacent to the lamina papyracea, (b) Coronal CT+C in another patient with opacification of the right ethmoid sinus (E) and a crescent shaped fluid collection adjacent to the medio-superior orbital wall

Orbital abscess, (a) Axial CT+C in a soft tissue window showing severe right sided proptosis with the entire right eyeball lying anterior to the interzygomatic line (dotted line), (b) Coronal image in the same patient showing a large intraorbital fluid collection with a thick enhancing rim (*) and sharp angles in relation to the orbital wall (long arrow), the floor of the frontal sinus shows a bony dehiscence (short arrow)

Cavernous sinus thrombosis, normal patient (a) Axial CT+C in a soft tissue window at the level of the skull base showing normal enhancement of the cavernous sinus (arrows), (b) CT+C in a different patient showing filling defects in the cavernous sinus with slight enlargement on the left side (arrow), indicative of thrombosis, axial images at different levels in the same patient showing (c) opacification of the sphenoid (arrow) and ethmoid sinuses in bone window and d) an extradural fluid collection with meningeal enhancement suspicious for empyema in soft tissue window

Cavernous sinus thrombosis, (a) Axial T1+C showing filling defects bilaterally in the cavernous sinus (arrows) and fluid in the sphenoid sinus, (b) Axial T1+C in the same patient showing a filling defect in the right ophthalmic vein (arrow), the findings are indicative of cavernous sinus thrombosis and thrombophlebitis in the ophthalmic vein caused by sphenoiditis

Dural arteriovenous fistula, T1+C (A) shows multiple tortuous flow voids (arrow) adjacent to the right sigmoid sinus, selective right ECA (B) and ICA (lateral view) (C) angiograms shows a DAVF type 1 with feeders (arrow) from the posterior meningeal branch of the middle meningeal artery and dural branches (arrow) from the cavernous ICA draining antegradely through the sigmoid sinus

Leptomeningitis: coronal T1+C of a patient that developed subdural empyema due to frontal sinusitis (not shown), the image shows increased enhancement of the leptomeninges of the frontal lobes (arrow), indicating leptomeningitis

Epidural and subdural empyema, (a) CT+C in soft tissue window in a patient with frontal sinusitis (not shown) showing an extra-axial fluid collection passing the midline (short arrow) anterior to the falx cerebri, the adjacent meninges are thickened and show strong enhancement (long arrow), these findings are indicative of an epidural empyema, (b) An extra-axial fluid collection in another patient with frontal sinusitis (not shown) running along the falx cerebri instead of passing it anteriorly (short arrow), again, the meninges are thickened and show increased enhancement (long arrow), these findings indicate subdural empyema

Subdural empyema

Cerebral abscess, patient who had recently been treated for sinusitis and now presented with a seizure, the CT shows an abnormality in the left temporal lobe with shaggy thick rim enhancement, and a large amount of vasogenic edema

Brain abscess, (a) CT+C showing an intra-axial fluid collection in the frontal lobe with rim enhancement (short arrow) and surrounding edema, in addition, a subdural collection with thickening and enhancement of the meninges is present (long arrow), (b) Axial T1+C, (c) DWI and (d) ADC map in the same patient showing a fluid collection in the frontal sinus with mucosal enhancement and restricted diffusion (long white arrow), a subdural fluid collection with thickened, enhancing meninges, and restricted diffusion (black arrow), and a fluid collection with rim enhancement in the left frontal lobe with restricted diffusion (short white arrow) and surrounding edema, the findings are indicative of frontal sinusitis with pus formation, subdural empyema and brain abscess

Focal cerebritis, (a) Axial CT in bone window showing an opacified right frontal sinus with a bony defect in the posterior sinus wall (arrow), (b) CT+C in a soft tissue window in the same patient showing a focal area of hypodensity in the right frontal lobe (short arrow) with faint enhancement in the centre, in addition, a subdural fluid collection can be seen (long arrow), (c) Axial FLAIR of the same patient showing an area of hyperintensity in the left frontal lobe (short arrow), these findings indicate frontal sinusitis with bony erosion causing subdural empyema and focal cerebritis

b) Mucous Retention Cyst :1-Incidence2-Radiographic Features

1-Incidence :-10% of population-Cysts occur from blockage of duct draining

glands-Most commonly in maxillary sinus (floor)

2-Radiographic Features :-On radiographs, they are radiopaque, dome-

shaped structures with a rounded edge, located on the floor of the maxillary sinus

-Cysts adhere to sinus cavity wall without causing bony expansion (in contradistinction to mucocele)

-Rounded soft tissue mass on MRI-MRI signal intensity depends on protein content :Low T1 , high T2 : serous contentHigh T1 , high T2 : high protein contentDark T1 and T2 : viscous content

T1 T2 T1+C

c) Polyps :1-Incidence2-Radiographic Features3-Sinonasal Polyposis4-Antrochoanal Polyp

1-Incidence :-Most common tumors of sinonasal cavity-Diseases associated with sinonasal polyps

include :1-Polypoid rhinosinusitis (allergy)2-Infection3-Endocrine disorders4-Rhinitis medica (aspirin)

2-Radiographic Features :-Location : ethmoidal sinus > nose-Soft tissue polyps are typically round-Bony expansion and remodeling-Very hyperintense on T2-Mucoceles may form as a result of blocked

draining ostia

3-Sinonasal Polyposis :-Refers to the presence of multiple benign polyps

in the nasal cavity and paranasal sinuses-Extensive mucosal polyps occupying and

obliterating the nasal cavity and the paranasal sinuses

-Associated local benign bone remodelling or erosion (as opposed to a mucocoele where the entire sinus is expanded)

4-Antrochoanal Polyp :-A solitary polyp that arises within the maxillary

sinus but passes through and enlarges the sinus ostium or more commonly an accessory ostium

-The nasal cavity is therefore extended posteriorly into the nasopharynx through the posterior chonca

-Represent only approximately 3-6% of sinonasal polyps

-CT :1-Defined mass with mucin density is seen arising

within the maxillary sinus2-Widening of maxillary ostium and extending in to

nasopharynx3-No associated bony destruction but rather

smooth enlargement of sinus-MRI :*T1 : intermediate to low signal *T2 : high homogeneous T2 signal*T1+C : peripheral enhancement

Antrochoanal polyp, axial (A) and coronal (B) CT show complete opacification of the right maxillary sinus with extension into the right middle meatus and inferior aspect of the right nasal cavity, there is thickening of the sinus walls but no sinus expansion

d) Destructive Sinusitis :-Causes :1-Mucormycosis2-Aspergillosis3-Wegener's granulomatosis4-Neoplasm

e) Fungal Sinusitis :1-Etiology2-Classification3-Radiographic Features

1-Etiology :a) Diabetesb) Prolonged antibiotic or steroid therapyc) Immunocompromised patient

2-Classification :-Broadly categorized as either invasive or

noninvasive -Invasive fungal sinusitis is defined by the

presence of fungal hyphae within the mucosa, submucosa, bone, or blood vessels of the paranasal sinuses

-Invasive fungal sinusitis is subdivided into acute invasive fungal sinusitis, chronic invasive fungal sinusitis, and chronic granulomatous invasive fungal sinusitis

-Noninvasive fungal sinusitis is defined by the absence of hyphae within the mucosal and other tissues of the paranasal sinuses

-Noninvasive fungal sinusitis is subdivided into allergic fungal sinusitis and fungus ball (fungal mycetoma)

a) Acute Invasive Fungal Sinusitisb) Chronic Invasive Fungal Sinusitisc) Chronic Granulomatous Invasive Fungal

Sinusitisd) Allergic Fungal Sinusitise) Fungus Ball

a) Acute Invasive Fungal Sinusitis :-Acute invasive fungal sinusitis is a rapidly progressing

infection seen predominantly in immunocompromised patients and patients with poorly controlled diabetes and rarely in healthy individuals, it is the most lethal form of fungal sinusitis, with a reported mortality of 50%-80%

-Noncontrast CT demonstrates hypoattenuating mucosal thickening or an area of soft-tissue attenuation within the lumen of the involved paranasal sinus and nasal cavity

-There is a predilection for unilateral involvement of the ethmoid and sphenoid sinuses

-Aggressive bone destruction of the sinus walls occurs rapidly with intracranial and intraorbital extension of the inflammation

Acute invasive zygomycosis in a 42-year-old man, CT+C shows right ethmoid and sphenoid sinusitis with destruction of the lateral wall of the right sphenoid sinus (arrow), there is invasion of the right cavernous sinus with occlusion of the right ICA

Acute invasive fungal sinusitis in a 39-year-old woman with diabetic ketoacidosis and acute left eye pain, (a) Axial unenhanced CT scan shows sinus disease in the ethmoid, maxillary, and sphenoid sinuses. Note the left-sided facial swelling, (b) Axial CT+C shows lack of enhancement in the left cavernous sinus (arrows) secondary to thrombosis from invasive fungal sinusitis, (c) Axial CT scan obtained craniad to b shows proptosis and periorbital inflammatory soft-tissue thickening on the left side (arrow)

Acute invasive aspergillosis in a 37-year-old man with acquired immunodeficiency syndrome who presented with proptosis of the left eye, axial unenhanced CT scans (a obtained craniad to b) show soft-tissue thickening in the left posterior ethmoid air cells, which is destroying the medial wall of the orbit and extending into the retro-orbital soft tissues (arrow)

Acute invasive zygomycosis in a 59-year-old man, (a) Axial unenhanced CT scan shows increased attenuation in the right anterior and posterior ethmoid air cells and right sphenoid sinus with soft-tissue thickening in the orbital apex (arrow), (b) Coronal unenhanced CT scan shows destruction of the medial wall and floor of the right orbit and disease extension into the orbit (arrows), (c) Axial unenhanced CT scan obtained caudad to a shows destruction of the posterior wall of the right maxillary sinus and obliteration of the periantral fat plane immediately posterior to the sinus (arrows)

Acute invasive fungal sinusitis due to zygomycosis in a 57-year-old diabetic man, (a) axial CT+C shows increased attenuation in the left anterior and posterior ethmoid air cells with destruction of the medial wall of the left orbit (arrow). (b) Coronal CT+C shows a subperiosteal abscess occupying the inferomedial aspect of the left orbit and displacing the medial and inferior rectus muscles laterally (arrows), note also the destruction of the orbital floor (arrowhead) and the increased attenuation in the adjacent left maxillary sinus

b) Chronic Invasive Fungal Sinusitis :-Inhaled fungal organisms are deposited in the nasal passageways and

paranasal sinuses, insidious progression occurs over several months to years in which fungal organisms invade the mucosa, submucosa, blood vessels, and bony walls of the paranasal sinuses

-This results in significant morbidity and may even be fatal-A hyperattenuating soft-tissue collection is seen at noncontrast CT

within one or more of the paranasal sinuses, it may be masslike and mimic a malignancy with destruction of the sinus walls and extension beyond the sinus confines

-There is decreased signal intensity on T1 and markedly decreased signal intensity on T2, mottled lucencies or irregular bone destruction may be seen in the paranasal sinuses

-There may also be sclerotic changes in the bony walls of the affected sinuses representing chronic sinus disease, Infiltration of the periantral soft tissues about the maxillary sinus is an indicator of invasive disease

-Differentiation between chronic invasive fungal sinusitis and malignant neoplasm may not be possible based on imaging findings 

 

Chronic invasive fungal sinusitis due to zygomycosis in a 44-year-old man, axial (a, b) and coronal (c, d) unenhanced CT scans show bilateral mucosal thickening in the maxillary sinuses, bone invasion is noted in the form of mottled areas of low attenuation in the zygomatic process of the right maxillary bone; this finding is best visualized on the images obtained with bone windows (arrows in b and d), there is also invasion into the soft tissues of the right cheek (arrowheads in a and c)

Chronic invasive fungal sinusitis due to zygomycosis in a 47-year-old woman, axial unenhanced CT scans (a obtained caudad to b) show increased attenuation in the left maxillary sinus, note the absence of the normal fat planes along the posterior wall of the left maxillary sinus, there is extension of infection beyond the walls of the maxillary sinus into the anterior and posterior periantral soft tissues (arrows), corresponding images obtained with bone windows showed osseous sclerotic changes in the left maxillary sinus, findings consistent with chronic sinus inflammatory changes

c) Chronic Granulomatous Invasive Fungal Sinusitis :

-Also known as primary paranasal granuloma and indolent fungal sinusitis, chronic granulomatous invasive fungal sinusitis is primarily found in Africa (Sudan) and Southeast Asia, with a few cases reported in the United States

-Cross-sectional imaging findings are expected to be similar to those of chronic invasive fungal sinusitis

d) Allergic Fungal Sinusitis :-The most common form of fungal sinusitis-There is usually involvement of multiple sinuses if

not pansinusitis and rhinitis, disease tends to be bilateral, and there is a frequent nasal component, the majority of the sinuses show near-complete opacification and are expanded

-Noncontrast CT demonstrates hyperattenuating allergic mucin within the lumen of the paranasal sinus

Allergic fungal sinusitis due to Bipolaris in a 22-year-old man with a long history of nasal obstruction, axial unenhanced CT scans show expansion of and increased attenuation in the anterior ethmoid, posterior ethmoid, sphenoid, and frontal sinuses bilaterally, there is characteristic hyperattenuating material within these sinuses (black arrows), note also the smooth thinning of the posterior wall of the left frontal sinus (white arrows in b)

Allergic fungal sinusitis due to Bipolaris in a 26-year-old man, (a, b) Coronal CT scans (a obtained posterior to b) show characteristic expansile, hyperattenuating material in the sphenoid, ethmoid, and right maxillary sinuses (arrows), extension into the nasal cavity (*) from the bilateral ethmoid sinuses and right maxillary sinus is noted, (c, d) Corresponding images obtained with bone windows show smooth erosion of the roofs of the posterior ethmoid sinuses (arrowheads in c) with intracranial extension, which is possibly limited by the dura, there is also smooth erosion of the medial wall of the right orbit (arrows in d) with intraorbital extension, which is possibly limited by the periosteum

e) Fungus Ball :-Also known as mycetoma, fungus ball is a relatively

uncommon manifestation of fungal sinusitis-Fungus ball appears as a mass within the lumen of

a paranasal sinus and is usually limited to one sinus

-The maxillary sinus is the most commonly involved sinus

-A fungus ball typically appears hyperattenuating at noncontrast CT due to dense matted fungal hyphae and may demonstrate punctate calcifications

Mucor fungus ball in a 49-year-old woman with chronic sinus pressure and halitosis, unenhanced CT scan shows isoattenuating to hyperattenuating material filling the right maxillary sinus with central calcific areas of increased attenuation (long arrow), note the circumferential thickening of the osseous walls of the sinus (short arrows), a finding consistent with a chronic inflammatory process

Aspergillus fungus ball in a 60-year-old woman with mixed connective tissue disorder and a history of cryoglobulinemia and Sjögren syndrome, axial unenhanced CT scan shows the typical hyperattenuating fungus ball with calcific foci in the left maxillary sinus (long arrow), note the sclerotic thickening of the osseous walls of the sinus (short arrows) from chronic sinus inflammation

3-Radiographic Features :-Bony destruction and rapid extension into

adjacent anatomic spaces-Indistinguishable from tumor, biopsy

required-Aspergillosis may appear hyperdense on

CT and hypointense on T1-If sphenoidal sinus alone is involved,

consider aspergillosis

f) Mucocele :1-Incidence2-Location3-Radiographic Features

1-Incidence :-True cystic lesion lined by sinus mucosa-Mucoceles occur as a result of complete

obstruction of sinus ostium (inflammation , trauma & tumor)

-The bony walls of the sinus are remodeled as the pressure of secretions increases

-In pediatric patients , consider cystic fibrosis

2-Location :-frontal 65% > ethmoidal 25% > maxillary

>10%-Sphenoidal (rare)-Patients with polyposis may have multiple

mucoceles

3-Radiographic Features :-Rounded soft tissue density-Typically isodense on CT-MR signal intensity :Low T1 , high T2 : serous contentHigh T1 , high T2 : high protein contentDark T1 and T2 : viscous content-Distortion and expansion of bony sinus walls-Nonenhancement unless infected (mucopyocele) ,

rim enhancement-Complication : breakthrough into orbit or anterior

cranial fossa

Mucocele of the frontal sinus

Ethmoid mucocele

Right ethmoid mucocele, coronal soft tissue (A) and axial bone algorithm (B) CT images show a completely opacified, mucus-filled and expanded right ethmoid sinus, focal dehiscence or erosion of the right lamina papyracea (arrow, B) is seen

Mucocele of the sphenoid and ethmoid sinuses

Axial unenhanced CT image shows opacification of the left sphenoid sinus due to a mass (arrow) causing slight expansion of the sinus, some parts of the sinus wall are thin and some are thick

T1 T2 T1+C

g) Inverted Papilloma :1-Incidence2-Radiographic Features3-Differetial Diagnosis

1-Incidence :-Unilateral polypoid lesion of the nasal cavity

and paranasal sinuses-Associated with HPV and malignancy-Commonly occur on the lateral wall of the

nasal cavity, most frequently related to middle turbinate and maxillary ostium

2-Radiographic Features :a) CT :-Non-specific, demonstrating a soft tissue

density mass with some enhancement-The location of the mass is one of the few

clues toward the correct diagnosis-Calcification is sometimes observed which

is helpful, as is focal hyperostosis which tends to occur at the site of tumor origin

CT images of a patient with inverted papilloma, A and B, Axial and coronal CT images show focal plaquelike hyperostosis in part of right ethmoid sinuses (arrows), C, Although tumor extends to the right maxillary sinus and nasal cavity, no additional foci of hyperostosis are seen, intraoperative endoscopic examination confirmed the limitation of tumor origin to the ethmoid sinuses

Coronal CT image in a patient with inverted papilloma shows localized cone-shaped hyperostosis of the superior wall of the posterior ethmoid sinus (white arrow), intraoperative endoscopic examination confirmed that the origin of tumor was located at the superior wall of the right posterior ethmoid sinus

Inverted papilloma, (a) Axial and (b) coronal CT show total opacification of the left maxillary sinus with medial bulging of the medial sinus wall into the nasal cavity, this was an inverted papilloma with the origin in the left maxillary sinus, a characteristic feature of many inverted papillomas is focal hyperkeratosis (arrows) at the origin of the tumor

b) MRI :*T1 : isointense to muscle*T2 : hyperintense to muscle , alternating

hypointense lines *T1+C : heterogenous enhancement ,

alternating hypointense lines

CT and MR images of patients with inverted papilloma of the maxillary sinus, A, Axial CT image of a patient with inverted papilloma shows cone-shaped focal hyperostosis involving the posterior wall of the left maxillary sinus (arrows), B, Sagittal T2 of the patient clearly shows the centrifugal pattern of tumor growth with a hyperostotic focus (white arrow) at the posterior wall of the left maxillary sinus, which was confirmed to be a tumor origin by surgery, C, Axial CT image of another patient shows cone-shaped hyperostosis (arrow) involving the anterior wall of the left maxillary sinus, which was proved to be the origin of inverted papilloma by intraoperative endoscopy

3-Differetial Diagnosis :1-Sinonasal carcinoma :-Unfortunately imaging is unable to confidently distinguish

between inverted papilloma , inverted papilloma with malignancy and pure malignancy

2-Antrochoanal polyp :-Only peripheral enhancement (if any)3-Inflammatory polyp :-Only peripheral enhancement (if any)4-Juvenile nasopharyngeal angiofibroma (JNA)5-Olfactory neuroblastoma6-Paranasal sinus mucocoele

h) Benign Tumors :1-Osteoma (most common paranasal sinus

tumor)2-Papilloma3-Fibroosseous lesions4-Neurogenic tumors5-Giant cell granuloma

Osteoma, (a) Axial and (b) coronal CT shows a high density, sclerotic osteoma localized in the left frontal recess (arrows), with time, the osteoma may grow and obstruct mucociliary clearance from the left frontal sinus

Osteoma, (a,b) Axial & coronal CT shows a large osteoma with ground-glass appearance (arrows) occupying the left posterior ethmoid sinus. The osteoma bulges into the orbit and displaces the sphenoid sinus posteriorly, (c) axial T2 demonstrates the signal void of the osteoma

Frontal sinus osteoma

i) Malignant Tumors :1-Types2-Tumor Spread

1-Types :a) SCC , 90 % :-Maxillary sinus , 80 %-Ethmoidal sinus , 15%b) Less common tumors , 10% :-Adenoid cystic carcinoma-Esthesioneuroblastoma (arises from olfactory epithelial cells,

commonly extends through cribriform plate)-Lymphoepithelioma-Mucoepidermoid carcinoma-Mesenchymal tumors : fibrosarcoma , rhabdomyosarcoma ,

osteosarcoma & chondrosarcoma-Metastases from lung , kidney & breast

2-Tumor Spread :a) Direct Invasion :-Maxillary sinus :Posterior extension : infratemporal fossa , pterygopalatine

fossaSuperior extension : orbit-Ethmoidal or frontal sinus : frontal lobeb) Lymph node metastases :-Submandibular , lateral pharyngeal & jugulodigastric nodesc) Perineural spread :-Pterygopalatine fossa-Connection to middle cranial fossa via foramen rotundum

Maxillary sinus squamous cell carcinoma, (a) Axial CT shows erosion of the lateral nasal wall and lacrimal duct (arrow) and growth into the middle meatus (asterisk) consistent with a T2 cancer, (b) Coronal CT in another patient with a carcinoma mimicking a nasal polyp, however, the lateral nasal wall is eroded (arrow)

Maxillary sinus squamous cell carcinoma, (a) Coronal CT and (b) coronal T1+C with fat saturation, CT is highly suspicious of tumor growth into the anterior orbit (arrow), however, the T1+C with fat saturation confirms that the periost acts as a strong barrier against tumor growth into the orbit (arrowheads)

Maxillary sinus squamous cell carcinoma, (a) Axial CT and (b) T2 demonstrate a tumor (black arrowheads) extending to the skin of the cheek (white arrowhead), the bony erosion of the lateral maxillary sinus wall and the pterygoid plates (arrows) are better visualized using CT; the extension of the tumor and distinction from obstructed fluid-filled sinuses and surrounding edematous soft tissue are best evaluated using MR imaging

Ethmoid sinus adenocarcinoma, (a) Coronal CT shows opacification of the left nasal cavity, anterior ethmoid sinus and frontal recess, the clue to a malignant process is the erosion of the lateral lamella (arrow), (b) CT+C coronal CT shows an intracranial component (arrowheads) verified at (c) coronal CT+C, there is no meningeal enhancement due to the dural barrier

Chondrosarcoma, (a) Axial CT of a well-delineated tumor of the maxillary and ethmoid sinuses, and nasal cavity (arrowheads), (b) Axial T2 shows high signal of the chondroid matrix with sparse, low signal areas of septa and calcifications, (c) T1+C shows contrast uptake in the septa and low signal in the surrounding chondroid matrix

B-cell lymphoma, (a) Axial and (b) coronal CT demonstrate advanced opacification of both maxillary sinuses (white arrowheads), At MR imaging, (c) axial T2 and (d) coronal T1+C demonstrate a large, bulky tumor on both sides of the maxillary sinus walls. MR imaging shows that the medial part of the right maxillary sinus contains mucus (black arrowheads) and that the epicentre of the tumor masses (asterisk) is close to the lateral sinus wall, which is a common finding in sinonasal B-cell lymphomas

Adenoid cystic carcinoma, coronal CT mimics the features of a simple polyp filling the left nasal cavity (arrowheads) and slightly remodelling the bones

Olfactory neuroblastoma, (a) Axial CT shows an expansile soft tissue mass remodelling the ethmoid bones (arrows), at MR imaging, (b) axial T2 shows a well-delineated tumor with homogeneous low signal (arrows) with surrounding high signal sinonasal fluid, (c) Axial T1 and (d) sagittal T1+C delineate the tumor (arrows) from the adjacent dark signal fluid-filled sphenoid sinus (asterisk). The sagittal image demonstrates the close relationship between the tumor and the ethmoid roof, (e) Axial DWI and (f) ADC map shows the characteristic low diffusion signal intensities (arrows) of a malignant tumor

Sinonasal undifferentiated carcinoma, (a) Coronal CT, (b) coronal T1+C with fat saturation and (c) coronal flair sequence demonstrating a highly aggressive tumor (arrows) with destruction of the lamina papyracea (black arrowheads) and the ethmoid roof (white arrowheads), the tumor enhances strongly after intravenous contrast medium and the fluid attenuated inversion recovery sequence demonstrates brain edema (arrowheads), immunohistologic examination concluded with SNUC

j) Small or Absent Sinuses :a) Congenital :1-Normal variant (5 % of population)2-Congenital Hypothyroidism3-Down’s syndrome (frontal sinuses absent

in 90 %)4-Kartagner’s syndrome

b) Acquired :-Secondary to overgrowth of bony wall :1-Paget’s disease2-Fibrous dysplasia3-Hemolytic anaemia4-Postoperative

h) Opaque Maxillary Antrum :a) Traumatic :1-Fracture2-Overlying soft tissue swelling3-Postoperative4-Epistaxis5-Barotraumab) Inflammatory :1-Sinusitis2-Allergy3-Mucocele

c) Neoplastic :1-Carcinoma (usually associated with bone

destruction & soft tissue mass)2-Lymphomad) Others :1-FD2-Cysts (dentigerous or mucous retention cyst)3-Wegner’s granulomatosis4-Anatomical5-Radiographic (overtilted view)

k) Mass in the Maxillary Antrum :1-Cyst :-Mucous retention cyst-Dentigerous cyst2-Trauma (herniation of orbital muscle through fracture)3-Neoplastic :-Polyps-Carcinoma4-Wegner’s granulomatosis :-Usually present in 40-50 years old-Mucosal thickening progresses to formation of soft tissue

mass with extensive bony destruction