Radiographic Features of Paranasal Sinuses

1. Paranasal Sinuses
Dr. Hadi Munib
Oral and Maxillofacial Surgery Resident

2. Outline
• Normal Development and Variations
• Diseases Associated with the Paranasal Sinuses
• Intrinsic Diseases of the Paranasal Sinuses
• Neoplasms
• Extrinsic Diseases of the Paranasal Sinuses
• References

3. Introduction
• Paranasal sinuses are the four paired sets of air-filled cavities of the
craniofacial complex composed of the maxillary, frontal, and sphenoid
sinuses and the ethmoid air cells.
• Abnormalities arising from within the maxillary sinuses can cause
symptoms that may mimic diseases of odontogenic origin, and vice
versa

4. Normal Development and Variations
• The paranasal sinuses develop as invaginations from the nasal fossae into their
respective bones.
• The mucosal lining of the paranasal sinuses is similar to that found in the nasal
cavity, but with slightly fewer mucus glands.
• In the absence of disease the epithelial cilia move mucus toward their
respective communications with the nasal fossae.
• The maxillary sinuses (maxillary antra or antra of Highmore) are the first to
develop in the second month of intrauterine life.
• An invagination develops in the lateral wall of the nasal fossa in the middle
meatus, and the sinus enlarges laterally into the body of the maxilla.
• At birth, each sinus is a thin, small slit no more than 8 mm in length in its
anteroposterior dimension.

5. Normal Development and Variations
• The maxilla becomes progressively more pneumatized as the air cavity expands
further into the bone both laterally under the orbits toward the zygomatic bone and
inferiorly toward the alveolar process.
• It may be very common to see the inferior (dependent) portion of the air-filled
maxillary sinus and floor near, or superimposed over, the roots of the premolar or
molar teeth.
• The floor of the maxillary sinus is a thin, radiopaque line on radiographs.
• Pneumatization.
• Draping; The very close relationship between the tooth roots and the maxillary sinus
is
• Closer examination of the periapical aspect of the teeth usually reveals intact laminae
durae and periodontal ligament spaces around the tooth root apices.
• The appearance of the maxillary sinus may be mistakenly confused with a benign
space-occupying lesion

6. Normal Development and Variations
• Hypoplasia of the maxillary sinuses occurs unilaterally in about 1.7% of
patients and bilaterally in 7.2%.
• The radiographic images of the affected sinus may appear more
radiopaque than normal because of the relatively large amount of
surrounding maxillary bone.
• Hypoplastic sinus vs. pathologically radiopaque; Configuration of
Maxillary Sinus walls
• A Waters view will show an inward bowing of the sinus wall resulting in
a smaller than normal air cavity.
• Extensive enlargement of the maxillary and other paranasal sinuses is a
well-known feature of acromegaly.

7. Normal Development and Variations
• Frontal sinuses; Development does not usually begin until the fifth or
sixth year.
• Develop either directly as extensions from the nasal fossae or from
anterior ethmoid air cells
• In about 4% of the population, the frontal sinuses fail to develop.
• The right and left frontal sinus cavities develop separately and as they
expand, they approach each other in the midline.
• In the adult, the frontal sinuses are often asymmetric cavities located
above the supraorbital ridges and the nasion.

8. Normal Development and Variations
• The sphenoid sinus begins growth in the fourth fetal month as
invaginations from the spheno-ethmoidal recesses of the nasal fossae.
• Located in the body of the sphenoid bone.
• The right and left sphenoid sinuses are separated by a bony septum and
are usually asymmetric in size and shape.
• The ostium of the sphenoid sinus is a relatively large-diameter opening.
• Blockages of the sphenoid sinus ostium are uncommon

9. Normal Development and Variations
• The ethmoid air cells extend into the ethmoid bones during the fifth
fetal month and continue to enlarge until the end of puberty.
• They consist of multiple interconnected, or sometimes separate, small
air-filled chambers that border the medial aspects of the orbital cavities
• The number of air cells varies considerably, with each ethmoid bone
containing between 8 and 15 cells.
• The ethmoid air cells may extend into the neighboring maxillary,
lacrimal, frontal, sphenoid, and palatine bones

10. Functions of Paranasal Sinuses
• Controversial.
• Heating and humidification of inhaled air
• Helping to reduce cranial weight
• Insulation or protection of deeper vital structures.

17. Diseases Associated with Paranasal Sinuses
• Diseases associated with the maxillary sinuses include:
• Intrinsic diseases; originating primarily from tissues within the sinus
• Extrinsic Diseases; outside the sinus (most commonly arising from
odontogenic tissues)
• These types of diseases include inflammatory odontogenic disease,
odontogenic cysts, benign and malignant odontogenic neoplasms,
bone dysplasias, and trauma.

18. Diseases Associated with Paranasal Sinuses
• The clinical signs and symptoms of maxillary sinus disease include:
• Feeling of pressure
• Altered voice characteristics
• Pain on head movement,
• Percussion sensitivity of the teeth or cheek region
• Regional dysesthesia, paresthesia or anesthesia
• Swelling of the facial structures adjacent to the maxilla.
• Diagnostic Imaging to help identify the cause and to rule out potential
causes

19. Diagnostic Imaging
• A periapical radiograph provides a detailed, limited view of the alveolar
recess and floor of the maxillary antrum.
• If during this examination the dentist suspects an abnormality, a maxillary
lateral occlusal projection may be used for a more extensive view of the
antrum.
• The panoramic radiograph depicts both maxillary sinuses, revealing
greater internal structure and parts of the inferior, posterior, and
anteromedial walls.
• It is difficult to compare the internal radiopacities of the right and left
sinus in the panoramic image.

20. Diagnostic Imaging
• The Waters projection is optimal for visualization of the maxillary sinuses,
especially to compare internal radiopacities, and the frontal sinuses and
ethmoid air cells
• If the Waters view is made with the mouth open, parts of the sphenoid
sinuses may also be visualized.
• The submentovertex view may be useful in evaluating the lateral and
posterior borders of the maxillary sinuses and the ethmoid air cells.
• The Caldwell view is most useful in evaluating the frontal sinuses and
ethmoid air cells. [15-degree Posterio-Anterior]
• The lateral skull view allows examination of all four pairs of the paranasal
sinuses.

21. Diagnostic Imaging
• CT and MRI have become increasingly important for evaluation of sinus
disease and have virtually replaced plane radiography and conventional
tomography for investigations of the paranasal sinuses.
• CT examination is appropriate to determine the extent of disease in
patients who have chronic or recurrent sinusitis

26. Intrinsic Diseases of the Paranasal Sinuses
• Abnormalities that originate from tissues within the sinuses.
• INFLAMMATORY DISEASE
• Inflammation may result from infection, chemical irritation, allergy,
introduction of a foreign body, or facial trauma.
• The radiographic changes associated with inflammation include
thickened sinus mucosa, air-fluid levels in the sinuses, polyps,
empyema, and retention pseudocysts.
• Viral infections may not cause any radiographic change in a sinus.

27. Mucositis
• Thickened sinus mucosa
• The mucosal lining of the paranasal sinuses is composed of respiratory
epithelium and is normally about 1 mm thick.
• Normal sinus mucosa is not visualized on radiographs
• When inflammation is present from either an infectious or allergic
process, it may increase in thickness 10 to 15 times, which may be seen
radiographically.
• Thickness of mucosa in asymptomatic individuals can vary considerably
• Discovery of thickened mucosa does not imply that treatment is required

28. Mucositis
• Thickening of the mucosal lining of the sinuses are unrecognized by the
patient and are discovered only incidentally on a radiograph.
• Radiographic Features
• Readily detectable in the radiograph as a non-corticated band
noticeably more radiopaque than the air-filled sinus, paralleling the
bony wall of the sinus

30. Sinusitis
• Generalized inflammation of the paranasal sinus mucosa caused by an
allergen, bacteria, or a virus.
• Sinusitis may cause blockage of drainage through the ostiomeatal
complex.
• Ciliary dysfunction and retention of sinus secretions.
• 10% of inflammatory episodes of the maxillary sinuses are extensions of
dental infections
• Pansinusitis; sinusitis affecting all the paranasal sinuses.
• In children with pansinusitis, the possibility of cystic fibrosis should be
considered.

31. Sinusitis
• Acute maxillary sinusitis is often a complication of the common cold,
• Accompanied by a clear nasal discharge or pharyngeal drainage.
• After a few days, the stuffiness and nasal discharge increase, and the
patient may complain of pain and tenderness to pressure or swelling over
the involved sinus.
• The pain may also be referred to the premolar and molar teeth on the
affected side
• Teeth may also be sensitive to percussion, this is more commonly seen in
bacterial sinusitis.
• A green or greenish yellow nasal discharge may also be appreciated.

32. Sinusitis
• This finding requires that the teeth be ruled out as a possible source of
the pain or infection.
• The key signs and symptoms are those of sepsis: fever, chills, malaise,
and an elevated leukocyte count.
• Acute sinusitis is the most common of the sinus conditions that cause
pain.
• Chronic maxillary sinusitis is typically a sequela of an acute infection
that fails to resolve by 3 months.
• No external signs occur except during periods of acute exacerbations
when increased pain and discomfort are apparent

33. Sinusitis
• Chronic sinusitis is often associated with anatomic derangements
• Deviation of the nasal septum and the presence of concha bullosa
(pneumatization of the middle concha) that inhibit the outflow of mucus.
• Chronic sinusitis is also often associated with allergic rhinitis, asthma, cystic
fibrosis, and dental infections.
• Radiographic Features
• More Radiopaque; Thickening of sinus mucosa and the accumulation of
secretions
• The most common radiopaque patterns that occur in the Waters view are
localized mucosal thickening along the sinus floor, generalized thickening of
the mucosal lining.

34. Sinusitis
• The image of thickened sinus mucosa on the radiograph may be uniform
or polypoid.
• Allergic reaction; the mucosa tends to be more lobulated.
• Infection; the thickened mucosal outline tends to be smoother, with its
contour following that of the sinus wall
• An air-fluid level resulting from the accumulation of secretions may also
be present.
• Radiopacities of transudates, exudates, blood, and pathologically
altered mucosa are similar.

35. Sinusitis
• Management
• The goals are to control the infection, promote drainage, and relieve
pain.
• Acute sinusitis is usually treated medically with decongestants to reduce
mucosal swelling and with antibiotics in the case of a bacterial sinusitis.
• Chronic sinusitis is primarily a disease of obstruction of the ostia; thus
the goal is ventilation and drainage.
• Endoscopic surgery to enlarge obstructed ostia or by establishing an
alternate path of drainage

39. Retention Pseudocyst
• Antral pseudocyst
• Benign mucous cyst
• Mucous retention cyst/ pseudocyst
• Mesothelial cyst
• Pseudocyst
• Interstitial cyst
• Lymphangiectatic cyst
• False Cyst
• Retention cyst of the maxillary Sinus

40. Retention Pseudocyst
• Retention Pseudocyst; describes several related conditions.
• The actual pathogenesis of these lesions is controversial.
• Blockage of the secretory ducts of seromucous glands in the sinus
mucosa may result in a swelling of the tissue.
• The serous non-secretory retention cyst arises as a result of cystic
degeneration within an inflamed, thickened sinus lining.
• Pseudocyst because of no epithelial lining

41. Retention Pseudocyst
• May be found in any of the sinuses at any time of the year but occur
more often in the early spring or fall.
• Changes in seasonal temperatures?
• More common in males.
• Rarely causes any signs or symptoms
• An incidental finding on radiographs.
• When the pseudocyst completely fills the maxillary sinus cavity, it may
prolapse (extrude) through the ostium and cause nasal obstruction and
postnasal discharge.

42. Retention Pseudocyst
• The pseudocyst may be present on radiographic examination of the
maxillary sinus, perhaps absent only a few days later, only to reappear
on subsequent examinations.
• The maxillary sinus is the most common site of retention pseudocysts.
• Antral retention pseudocysts are not related to extractions or associated
with periapical disease.

43. Retention Pseudocyst
• Location; best demonstrated in Extraoral radiographs, usually form on
the floor of the sinus and some may form on the lateral walls or the roof
• Periphery and Shape; well-defined, non-corticated, smooth, dome-
shaped radiopaque masses, no osseous border surrounds it.
• Internal Structure; homogeneous and more radiopaque than the
surrounding air of the sinus cavity
• Effects on Surrounding Structures; There are no effects on the
surrounding structures

44. Retention Pseudocyst
• Differential Diagnosis
• Odontogenic cysts
• Antral Polyps; from infectious or allergic origin are more often multiple.
• They are also commonly associated with a thickened mucous
membrane, which is less frequently observed with retention
pseudocysts.
• Rounded Neoplastic Mass
• Management; Retention pseudocysts in the maxillary sinus usually
require no treatment

47. Polyps
• The thickened mucous membrane of a chronically inflamed sinus
frequently forms into irregular folds.
• May develop in an isolated area or in a number of areas throughout the
sinus.
• May cause displacement or destruction of bone.
• Ethmoid air cells; polyps may cause destruction of the medial wall of
the orbit (lamina papyracea of the ethmoid bone) and a unilateral
proptosis.

48. Polyp
• Radiographic Features
• A polyp may be differentiated from a retention pseudocyst
• A polyp usually occurs with a thickened mucous membrane lining because the
polypoid mass is no more than an accentuation of the mucosal thickening.
• Retention pseudocyst; the adjacent mucous membrane lining is not usually
apparent.
• The radiographic image of the bone displacement or destruction associated
with polyps may mimic a benign or malignant neoplasm.
• Examination of a paranasal sinus that reveals bone destruction associated
with radiopacification is an indication for biopsy.

50. Antrolith
• Occur within the maxillary sinuses
• Result of deposition of mineral salts such as calcium phosphate, calcium
carbonate, and magnesium around a nidus
• May be introduced into the sinus (extrinsic)
• Intrinsic such as masses of stagnant or inspissated mucous or cellular
debris in sites of previous inflammation.
• The smaller antroliths are usually asymptomatic
• If they continue to grow; sinusitis, bloodstained nasal discharge, nasal
obstruction, or facial pain.

51. Antrolith
• Radiographic Features
• Location; within the maxillary sinus and thus are positioned above the
floor of the maxillary antrum
• Periphery and Shape; well-defined periphery and may have a smooth
or irregular shape.
• Internal Structure; may vary in density from a barely perceptible
Radiopacity to an extremely radiopaque structure.
• May be homogenous or heterogeneous, and in some instances
alternating layers of radiolucency and Radiopacity in the form of
laminations may be seen.

52. Antrolith
• Differential Diagnosis
• Root fragments in the sinus; the presence of a root canal and the
fragment may move when radiography is performed with the head in
different positions,
• Rhinoliths; are similar calcifications but are found within the nasal
fossae. Posteroanterior and lateral skull views
• Management; removal of symptomatic antroliths.

55. Mucoceles
• Pyocele, Mucopyocele
• An expanding, destructive lesion that results from a blocked sinus
ostium.
• The blockage may result from intra-antral or intranasal inflammation,
polyp, or neoplasm.
• The entire sinus thus becomes the pathologic cavity.
• The increase in intra-antral pressure results in thinning, displacement,
and, in some cases, destruction of the sinus walls.
• Pyocele, Mucopyocele, Empyema; When the cavity is filled with pus.

56. Mucocele
• Clinical Features
• A mucocele in the maxillary sinus may exert pressure on the superior alveolar
nerves and thus cause radiating pain.
• First complaint of a sensation of fullness in the cheek.
• This swelling may first become apparent over the anteroinferior aspect of the
antrum, the area where the wall is thin, or destroyed.
• If the lesion expands inferiorly, it may cause loosening of the posterior teeth in
the area.
• If the medial wall of the sinus is expanded, the lateral wall of the nasal cavity
will deform.
• Should it expand into the orbit, it may cause diplopia (double vision) or
proptosis (protrusion of the globe of the eye).

57. Mucocele
• Radiographic Features
• Location; About 90% of mucoceles occur in the ethmoid air cells and
frontal sinuses and rarely in the maxillary and sphenoid sinuses.
• Periphery and Shape; The normal shape of the sinus is changed into a
more circular, “hydraulic” shape as the mucocele enlarges.
• Internal Structure; is uniformly radiopaque

58. Mucoceles
• Differential Diagnosis
• Neoplasm
• A large odontogenic cyst
• An occluded ostium should strengthen the likelihood of a mucocele.
• CT is the imaging method of choice for making these distinctions.
• Management; usually surgical, with a Caldwell-Luc

61. Neoplasms
• Benign neoplasms of the paranasal sinuses other than inflammatory polyps are
rare.
• The radiographic images of such benign neoplasms are nonspecific.
• Usually the involved portion of the sinus appears radiopaque because of the
presence of a mass, and there may be displacement of adjacent sinus borders.
• The most common malignant neoplasms of the paranasal sinuses are
squamous cell carcinomas and malignant salivary gland neoplasms.
• Of carcinomas of the paranasal sinuses, 74% originate in the maxillary sinus.
• Although radiopacification is a feature of both the inflammatory conditions
and neoplasms, bone destruction is more common with malignant neoplasms.

62. Benign Neoplasms - Papilloma
• The epithelial papilloma is a rare neoplasm of respiratory epithelium that
occurs in the nasal cavity and paranasal sinuses.
• Predominantly in men.
• Unilateral nasal obstruction, nasal discharge, pain, and epistaxis may occur.
• The patient may have complained of recurring sinusitis for years and a
subsequent nasal obstruction on the same side as the sinusitis.
• The epithelial papilloma has a 10% incidence of associated carcinoma.
• The diagnosis can be made only by histopathologic examination of the tissue.
• Location; The epithelial papilloma is usually in the ethmoidal or maxillary sinus.
• Internal Structure; homogeneous radiopaque mass of soft tissue density.
• Effects on Surrounding Structures; If bone destruction is apparent, it is the
result of pressure erosion.

63. Benign Neoplasms - Osteoma
• The osteoma is the most common of the mesenchymal neoplasms in
the paranasal sinuses.
• Almost twice as common in males as females and are most common in
the second, third, and fourth decades.
• Most are usually slow growing and asymptomatic
• Incidental finding
• Symptoms due to obstruction of the sinus ostium or infundibulum or
• The result of erosion or deformity, orbital involvement, or intracranial
extension.

64. Osteoma
• Radiographic Features
• Location; Although osteomas occasionally develop in the maxillary sinus, they
more often occur in the frontal and ethmoidal sinuses.
• The incidence in the maxillary antrum varies between 3.9% and 28.5% of the
incidence in all paranasal sinuses.
• Periphery and Shape; lobulated or rounded and has a sharply defined margin
• Internal Structure; homogeneous and extremely radiopaque.
• Differential Diagnosis
• Antrolith, Mycolith, teeth, odontomas, or odontogenic neoplasms
• These are all usually not as homogeneous in appearance as the osteoma.

67. Malignant Neoplasms of the Paranasal Sinuses
• Malignant neoplasms of the paranasal sinuses account for less than 1% of all
malignancies in the body.
• Squamous cell carcinoma, comprising 80% to 90% of the cancers in this site, is by far
the most common primary malignant neoplasm of the paranasal sinuses.
• Other primary neoplasms include adenocarcinoma, carcinomas of salivary gland
origin, soft and hard tissue sarcomas, melanoma, and malignant lymphoma.
• Factors that contribute to a poor prognosis for cancer include the advanced stage of
the disease when it is finally diagnosed and the close proximity of vital anatomic
structures.
• The clinical signs and symptoms may masquerade as an inflammatory sinusitis.
• The early primary lesions may only appear as a soft tissue mass in the sinus before
they cause bone destruction.
• Any unexplained radiopacity in the maxillary sinus of an individual older than 40 years
should be investigated thoroughly.

68. Squamous Cell Carcinoma
• Likely originates from metaplastic epithelium of the sinus mucosal
lining.
• The most common symptoms of cancer in the maxillary sinus are facial
pain or swelling, nasal obstruction, and a lesion in the oral cavity.
• The mean age of the patient is 60 years, Twice as many men as women
are affected.
• Lymph nodes are involved in about 10% of cases, and the symptoms are
present for about 5 months before diagnosis.
• The symptoms produced by malignant neoplasms in the maxillary sinus
depend on which wall(s) of the sinus is/are involved.

69. Squamous Cell Carcinoma
• The medial wall is usually the first to become eroded, leading to such nasal
signs and symptoms as obstruction, discharge, bleeding, and pain.
• Lesions that arise on the floor of the sinus may first produce dental signs and
symptoms, including expansion of the alveolar process, unexplained pain and
altered sensation of the teeth, loose teeth, swelling of the palate or alveolar
ridge, and ill-fitting dentures.
• The neoplasm may erode the sinus floor and penetrate into the oral cavity.
• Such oral manifestations appear in 25% to 35% of patients with cancer in the
maxillary sinus.
• When the lesion penetrates the lateral wall, facial and vestibular swelling
becomes apparent and the patient may complain of pain and hyperesthesia of
the maxillary teeth.

70. Squamous Cell Carcinoma
• Signs and symptoms related to the eye: diplopia, proptosis, pain, and
hyperesthesia or anesthesia and pain over the cheek and upper teeth.
• Location; Most carcinomas occur in the maxillary sinuses, but
involvement of the frontal and sphenoid sinuses is also comparatively
common.
• Internal Structure; has a soft tissue radiopaque appearance.
• Effects on Surrounding Structures; As the lesion enlarges, it may destroy
sinus walls and in general, cause irregular radiolucent areas in the
surrounding bone.

71. Squamous Cell Carcinoma
• Additional Imaging
• If a conventional radiograph of any radiopacified sinus reveals the slightest suggestion of
bone destruction, advanced imaging is imperative
• On CT, the most characteristic sign of malignancy is invasion into the soft tissue facial
planes beyond the sinus walls
• Consequently, CT is useful in revealing the extent of paranasal sinus neoplasms, especially
when extension into the orbit, infratemporal fossa, or cranial cavity has occurred.
• MRI examinations are excellent for revealing the extent of soft tissue penetration into
adjacent structures and in differentiating mucus accumulation from the soft tissue mass of
the neoplasm.
• Differential Diagnosis; includes all the conditions that may cause Radiopacity of the
antrum
• Sinusitis, large retention pseudocysts, and odontogenic cysts.
• It is important to note that bone destruction may also occur in infectious and some benign
conditions.

72. Squamous Cell Carcinoma
• Neoplasms should be suspected in any older patient in whom chronic
sinusitis develops for the first time without an obvious cause.
• Management; Generally combines surgery and radiation therapy.
• Malignant neoplasms in the paranasal sinuses usually have a poor
prognosis because they are usually well advanced by the time of
diagnosis.
• Inaccurate preoperative staging
• Complex anatomy of the region.

75. Pseudotumor
• Invasive fungal sinusitis, inflammatory pseudotumor, fibro inflammatory
pseudotumor, plasma cell granuloma, sinonasal fungal disease, mucormycosis,
aspergillosis, zygomycosis of the paranasal sinuses, and Rhizopus sinusitis
• A descriptive name for a group of apparently related diseases of fungal origin that
occur in the paranasal sinuses and in other parts of the head and neck.
• Often occurs after a series of recurrent infections.
• Not very specific Symptoms; there may be recurring pain and a mass simulating a
neoplasm [erosion of thewalls of the involved sinus and proptosis if the orbit is
involved.
• Altered nerve function resulting from involvement of the nerve or occlusion of
blood vessels by the mass has also been reported.
• Many cases appear in patients who are immunocompromised or who have systemic
diseases

76. Pseudotumor
• Radiographic Features; masses simulating malignant neoplasms that
cause erosion of bony walls of the involved sinuses.
• Differential Diagnosis; benign and malignant neoplasms.
• Management; debridement of the sinuses and administration of
antifungal medication, a Caldwell-Luc surgical approach, and therapy.

77. Extrinsic Diseases involving the Paranasal Sinuses
• INFLAMMATORY DISEASES
• Dental inflammatory lesions may cause a localized mucositis in the adjacent
floor of the maxillary antrum.
• This is a result of the diffusion of inflammatory exudate (mediators) beyond the
cortical floor of the antrum and into the periosteum and the mucosal lining of
the sinus.
• The localized type of mucositis related to dental inflammatory disease usually
resolves in days or weeks after successful treatment of the underlying cause.
• Radiographic Features
• The involved mucosa presents as a homogeneous radiopaque, ribbon-shaped
shadow that follows the contour of the floor of the maxillary sinus
• The thickened mucosa is usually centered directly above the inflammatory
lesion.

78. Periostitis
• The exudate from dental inflammatory lesions can diffuse through the
cortical boundary of the antral floor.
• These products can strip and elevate the periosteal lining of the cortical
bone of the floor of the maxillary antrum.
• Stimulating the periosteum to produce an elevated thin layer of new
bone adjacent to the root apex of the involved tooth.
• The presence of one or more halo-like layer(s) of new bone indicates
inflammation of the periosteum.

79. Periostitis
• Radiographic Features
• Although the periosteal tissue is not visible on the radiograph per se,
• Referred to as periosteal new bone formation.
• This new bone may take the form of one or more thin radiopaque lines,
or the line may be very thick.
• This new bone should be centered directly above the inflammatory
lesion.

81. Benign Odontogenic Cysts and Tumors
• Odontogenic cysts are the most common group of extrinsic lesions that
encroach on the maxillary sinuses.
• The most common are radicular cysts, followed by Dentigerous cysts and
odontogenic Keratocyst
• As the odontogenic cyst grows, its border becomes indistinguishable from the
sinus border.
• With continued growth, the cyst encroaches on the space of the sinus,
displaces its borders, and the air-filled space decreases in volume
• A thin radiopaque line divides the contents of the cyst from the sinus cavity.
• This appearance is in contrast to a retention pseudocyst, which, being inside
the sinus, does not have a cortex around its periphery.

82. Odontogenic Cysts
• Radiographic Features
• Periphery and Shape; curved or oval shape defined by a corticated
border.
• Internal Structure; homogeneous and radiopaque relative to the air-
filled sinus cavity, radiopacity may appear to be that of bone resulting
from the extreme contrast to the radiolucent air within the sinus.
• Effects on Surrounding Structures; may displace the floor of the
maxillary antrum.

83. Odontogenic Cysts
• Differential Diagnosis
• Retention Pseudocyst; only odontogenic cysts have a cortex at the
periphery
• Dentigerous cyst vs. odontogenic Keratocyst that has a pericoronal
relationship to the third molar.
• Management of Underlying cause, healing will start.

88. Odontogenic Tumors
• Benign Tumors can cause Nasal Obstruction, Facial Deformity, Displacement
and Loosening of teeth
• The nature of bony barriers of the face, and the relatively good blood supply,
are also responsible for efficient local spread.
• Ameloblastoma and Myxoma, show more aggressive pattern of growth in the
maxilla and have a closer proximity to vital structures in the skull base.
• Radiographic Features
• Periphery and Shape; Curved, oval, or multilocular shape that may be
defined by a thin cortical border as it encroaches on the sinus. More
aggressively growing tumors may even lack a portion of the border.
• Internal Structure; Coarse or fine septae or regions of dystrophic calcification,
depending on the histopathologic nature of the tumor.

89. Odontogenic Tumors
• Effects on Surrounding Structures.
• The tumor may displace the floor of the maxillary antrum and cause
thinning of the peripheral cortex.
• The tumor may enlarge to the point where it has almost completely
encroached on the sinus air space, and this residual space may appear
as a thin saddle over the tumor.
• The bony walls of the sinus may be thinned or eroded, and adjacent
structures may be displaced.

93. Fibrous Dysplasia
• May arise adjacent to any of the paranasal sinuses causing displacement of
sinus borders, and result in a smaller sinus on the affected side.
• Clinical Features
• The involvement of the facial skeleton can result in facial asymmetry, nasal
obstruction, proptosis, pituitary gland compression, impingement on cranial
nerves, or sinus obliteration.
• Sinus obliteration results when the expanding dysplastic bone encroaches on
it.
• The lesion may displace the roots of teeth and cause teeth to separate or
migrate, but it usually does not cause root resorption.
• Fibrous dysplasia is more common in children and young adults
• Growth of the dysplastic bone usually ceases at the age of skeletal maturity

94. Fibrous Dysplasia
• Radiographic Features
• Location; The posterior maxilla is the most common location.
• Periphery; The lesion itself is usually not well defined, tending to blend into
the surrounding bone. The external cortex of the bone as well as the sinus
floor is intact but displaced.
• Internal Structure; The normal radiolucent maxillary antrum may be partially
or totally replaced by the increased Radiopacity of this lesion.
• The degree of Radiopacity depends on its stage of development and the
relative amounts of bone and fibrous tissue present.
• Usually the radiopaque areas have the characteristic ground-glass
appearance on Extraoral radiographs or an orange-peel appearance on
intraoral views

95. Fibrous Dysplasia
• Differential Diagnosis
• Not difficult in young patients
• Paget’s disease of bone does not usually obliterate the sinus.
• Ossifying fibroma; may also have a soft tissue capsule and may be more
Expansile. Sometimes Difficult to be differentiated from each other

98. Dental Structures Displaced into the Sinus
• Tooth roots may be fractured from various forms of trauma, including
iatrogenic causes.
• They may be displaced into the sinus during extraction or subsequent
attempts to retrieve them

99. Dental Structures Displaced into the Sinus
• Clinical Features
• No specific features may be visible if the root was displaced into the
sinus recently.
• Sometimes asking the patient to hold his or her nose while attempting
to breathe out through it -Valsalva maneuver- will cause bubbles to
appear within the blood contained within the fresh extraction socket.
• If the patient has had the root or tooth in the sinus for a number of
days, the presenting symptom may be sinusitis.

100. Dental Structures Displaced into the Sinus
• Radiographic Features
• Location; Premolar or molar teeth or root fragments. Sometimes they
may be submucosal, between the osseous wall of the sinus and the
periosteum.
• Lateral maxillary occlusal views are useful for examining the maxillary
sinus for displaced teeth or root fragments.
• Periphery and Shape; No immediate evidence of change may be, the
disruption of the sinus wall may be difficult or impossible to see on
radiographs.

101. Dental Structures Displaced into the Sinus
• Internal Structure; In the early stages, no internal structural changes
are present, except that the dental fragment may appear as a
radiopaque mass
• Effects on Surrounding Structures; The dental fragment usually has no
effect on surrounding structures; A break in the floor of the maxillary
sinus caused by the displacement of the tooth
• Differential Diagnosis; Bony masses that are exostoses of the sinus wall,
Septa and Antrolith
• Presence of Pulp Canal

105. References
• Chapter 27: Paranasal Sinuses

106. THANK YOU!