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Section 6 Systemic Disorders/Surrounding Structures Involving PNS346
A B
Figs. 24.18A and B: Osteonecrosis of maxilla (postradiotherapy). (A) Bilateral maxillary
sinusitis (arrows); and (B) Osteolysis of maxilla with absent teeth (asterisks). Missing maxilla
appearance.
■ Imaging:
• Panoramic radiography: Osteolysis of maxilla with oating teeth—
“missing maxilla appearance”.
• Noncontrast computed tomography (Figs. 24.17 and 24.18): Osteolysis
with periosteal reaction, and sequestrum formation. Mixed lytic
sclerotic appearance may be seen especially in bisphosphonateinduced osteoradionecrosis.
CONCLUSION
Dental lesions are an important dierential of unilateral sinus disease or
infrequently even bilateral maxillary sinus diseases.
REFERENCES
1. Broderick DF. e opacied paranasal sinus: approach and dierential. Appl
Radiol. 2015;44:9-17.
2. Mafee MF, Tran BH, Chapa AR. Imaging of rhinosinusitis and its complications:
plain lm, CT, and MRI. Clin Rev Allergy Immunol. 2006;30(3):165-86.
3. Sen S, Chandra A, Mukhopadhyay S, et al. Sinonasal tumors: computed Tomography and MR imaging features. Neuroimaging Clin N Am. 2015;25(4):595-618.
4. Whyte A, Chapeikin G. Opaque maxillary antrum: a pictorial review. Australas
Radiol. 2005;49(3):203-13.
5. Kheir E, Stephen L, Nortje C, et al. e imaging characteristics of odontogenic
myxoma and a comparison of three dierent imaging modalities. Oral Surg Oral
Med Oral Pathol Oral Radiol. 2013;116(4):492-502.
6. Desai SM, Dubey RB, Tara NP. Giant cell tumor of sinonasal cavity an uncommon
location for a common bone tumor. Indian J Radiol Imaging. 2003;13(1):13 4.
7. Connor SE. e skull base in the evaluation of sinonasal disease: role of com puted
tomography and MR Imaging. Neuroimaging Clin N Am. 2015;25(4):619-51.
8. Smith J, Birkeland AC, McHugh JB, et al. Maxilla Osteonecrosis: a dierential
diagnosis in patients with metastatic cancer on bisphosphonates. J Case Rep
Med. 2016;5:235969.
347Chapter 24 Imaging of Dental Lesions and Sinonasal Cavity
25
CHAPTER
Imaging of Disorders Involving
Sinonasal Cavity and Orbit
Ashu Seith Bhalla, Smita Manchanda
• Introduction
• Infections
– Complicated Acute Sinusitis
– Invasive Fungal Sinusitis
• Inammatory Disorders
– Orbital Pseudotumor
• Tumors
– Direct Extension
– Extension through Inferior Orbital
Fissure
– Spread through Nasolacrimal
Duct
– Perineural Spread
• Trauma
INTRODUCTION
Pathologies of the nasal cavity and paranasal sinuses frequently involve the
orbits and vice-versa. ese include infections and tumors with the spread
of disease from paranasal sinuses to orbit being much more common. e
spectrum of these disorders is enlisted in Table 25.1.
Table 25.1: Disorders involving sinonasal cavity and orbit.
Infections • Complicated acute sinusitis
• Invasive fungal sinusitis
Inammatory disorders • Orbital pseudotumor
Tumors • Direct extension
• Extension through inferior orbital ssure
• Spread through nasolacrimal duct (NLD)
• Perineural spread
Trauma • Component of complex facial fractures
INFECTIONS
Complicated Acute Sinusitis
■ About two-thirds of signicant orbital infection results from adjoining
sinusitis, the rest being due to foreign bodies.
349Chapter 25 Imaging of Disorders Involving Sinonasal Cavity and Orbit
A
C
B
Figs. 25.1A to C: Orbital complication of
sinusitis. Subperiosteal abscess. (A) Mucosal
disease right ethmoid and sphenoid sinuses
(white arrow); and (B and C) Subperiosteal
abscess (asterisks) with air foci (black arrow in A)
along roof and medial wall of right orbit.
■ Orbital cellulitis may be the rst presenting symptom of sinusitis in
children.
1,2
■ On imaging, it is important to dierentiate preseptal (periorbital) cellulitis
from postseptal (orbital) cellulitis as clinical presentation can be similar.
e demarcation between the two is the brous orbital septum.
■ Orbital cellulitis requires aggressive management as it is a threat to vision
of the patient.
■ Orbital abscess: Rim-enhancing collection with central part showing
restricted diusion (Figs. 25.1A to C).
■ Inammation from orbit can extend along nasolacrimal duct (NLD) till
inferior meatus (Figs. 25.2A and B).
■ Severe infection can occasionally result in the orbital compartment
syndrome (OCS). is is a serious emergency requiring immediate
decompression. On imaging, it is recognized by the presence of proptosis
with periorbital edema, tenting of the posterior wall of the globe,
retrobulbar fat stranding, and a stretched optic nerve.
Section 6 Systemic Disorders/Surrounding Structures Involving PNS350
A B
Figs. 25.2A and B: Right orbital cellulitis and nasolacrimal duct (NLD) inammation.
(A) Right orbital and periorbital cellulitis with abscess formation (arrow); and (B) Inammation
extending along right NLD till lower end (arrowhead).
Flowchart 25.1: Evolution of orbital complications.
■ Inammatory edema results in swelling of eyelid. However, in early stages
when the term inammatory edema is used, there is only soft tissue
swelling but there is no spread of infection into the orbit. Computed
tomography (CT)/magnetic resonance imaging (MRI) reveals secretions
conned to the sinuses.
■ Further evolution of orbital complications, especially if untreated is
detailed in the algorithm (Flowchart 25.1).
351Chapter 25 Imaging of Disorders Involving Sinonasal Cavity and Orbit
A
C
B
Figs. 25.3A to C: Invasive fungal sinusitis.
(A) Soft tissue density in right ethmoid sinuses
exten ding into right orbit (asterisk); (B)
Erosion of lamina papyracea (arrow); and (C)
Hypointense signal of soft tissue (arrowhead)
on T2-weighted image (T2WI) with hyperintense
mucosal thickening (black arrow).
Invasive Fungal Sinusitis
■ Acute invasive fungal sinusitis is indistinguishable from bacterial
cellulitis.
■ Proptosis and periorbital inammation can be seen.
■ Optic nerve appears stretched with ill-dened outline.
■ Magnetic resonance signs include necrosis with variable or nonenhancement of aected extraocular muscles.
■ Globe may show deformity with tenting of the posterior wall—“Guitarpick sign”.
■ Increase signal intensity of vitreous on inversion recovery [uidattenuated inversion recovery (FLAIR)] sequences indicates invasion of
the globe (endophthalmitis).
■ In cases of endophthalmitis thickening and enhancement of the wall of
the globe is also seen. is is an ocular emergency.
■ Chronic invasive fungal sinusitis (Figs. 25.3A to C) is seen as soft tissue in
sinuses with bone erosion and extension into orbital cavity. Resembles
locally invasive diseases like pseudotumor.
2,3
Section 6 Systemic Disorders/Surrounding Structures Involving PNS352
A B
Figs. 25.4A and B: Pseudotumor. (A) Soft tissue (asterisk) in nasal cavity and bilateral
orbits; and (B) Erosion of left lamina papyracea (arrow).
INFLAMMATORY DISORDERS
Orbital Pseudotumor
■ It is a nongranulomatous inammatory lesion involving multiple orbital
compartments. Lesion is usually conned to orbit, may occasionally
spread to adjoining sinuses.
■ Characteristic painful and bilateral in up to a fourth of patients.
■ Soft tissue density on noncontrast CT (NCCT) (Figs. 25.4A and B) and
shows low signal intensity on T2W fat suppressed images.
■ D/D: Chronic invasive fungal sinusitis, lymphoma, and immunoglobulin
G-4 (IgG4)-related disorders (see Chapter 22).
TUMORS
As in inammatory conditions, spread of tumors from paranasal sinuses to
orbit is far more frequent than the reverse spread from orbit to sinuses.
4,5
Direct Extension
■ Contiguous extension of maxillary sinus tumors and ethmoid sinus
tumors can occur by erosion of the intervening orbital oor and lamina
papyracea, respectively (Figs. 25.5 and 25.6).
■ Earliest sign of orbital inltration is the elevation of periorbita with loss
of interface between the tumors and periorbita. “Periorbita” refers to the
periosteum of the bony orbital walls, and provides a barrier to spread of
tumor. On MRI, it appears hypointense (similar to cortical bone), and
loss of this hypointensity is seen once periorbita is breached.
■ Subsequently there is involvement of the extraocular muscles which may
be displaced or thickened with abnormal enhancement.
■ Orbital fat stranding is seen.
■ Direct sign is disruption of the bony orbital wall (Figs. 25.6A to C).
353Chapter 25 Imaging of Disorders Involving Sinonasal Cavity and Orbit
A
B
Figs. 25.5A and B: Direct tumor extension into orbit (squamous cell carcinoma). (A)
Large intermediate signal intensity mass left in maxillary and ethmoid sinuses (asterisk); and
(B) Orbital extension by erosion of orbital oor and lamina papyracea (arrow) deforming the
globe.
A
B
Figs. 25.6A to C: Direct tumor extension
into orbit [primitive neuroectodermal tumor
(PNET) maxilla]. (A) Large expansile mildly
enhancing mass left in maxilla (asterisk); (B)
Mixed lytic sclerotic pattern of bone destruction
(arrow). Orbital extension by erosion of orbital
oor (arrowhead); and (C) Widening of infer ior
orbital ssure (asterisk), pterygomaxillary
ssure, and extension into infratemporal fossa
C
(arrow).
Section 6 Systemic Disorders/Surrounding Structures Involving PNS354
Extension through Inferior Orbital Fissure
■ Tumors extending to pterygopalatine fossa and infratemporal fossa may
spread to the orbit through inferior orbital ssure (Figs. 25.7A and B).
Spread through Nasolacrimal Duct
■ Primary tumors (e.g. adenoid cystic carcinoma) of NLD show soft tissue
and enlargement of NLD canal (Figs. 25.8A and B).
A
Figs. 25.7A and B: Extension through inferior orbital ssure (juvenile nasopharyngeal
angiobroma-atypical aggressive form with bone erosion). (A) Intensely enhancing
hetero geneous mass lesion in nasal cavity, nasopharynx laterally extending into the pterygomaxillary ssure (asterisk); and (B) Extension into orbit through direct extension/bone erosion
(white arrow in A) and widened inferior orbital ssure (black arrow in B).
A
Figs. 25.8A and B: Adenoid cystic carcinoma in nasolacrimal duct. (A) Mildly enhancing
soft tissue seen along the right nasolacrimal duct (arrow); and (B) Widened canal on right
side (asterisk).
B
B
355Chapter 25 Imaging of Disorders Involving Sinonasal Cavity and Orbit
A
C
Figs. 25.9A to D: Nasolacrimal duct melanoma. (A) Soft tissue density mass along left
lacrimal sac and nasolacrimal duct (asterisk); (B and C) Mildly hyperintense on T1-weighted
image (T1WI) (arrow in B), hypointense on T2WI (arrow in C); and (D) Heterogenous
postcontrast enhancement (arrow in D).
B
D
■ Tumors involving the nasal cavity can spread to orbit through the NLD.
Similarly, tumors originating in the lacrimal sac may spread downward
along the NLD (Figs. 25.9A to D).
Perineural Spread
■ Once maxillary sinus tumors invade the premaxillary soft tissue these
may spread along the infraorbital nerve and then through infraorbital
foramen to the orbit.
TRAUMA
Orbit fractures (Table 25.2) are often a component of more complex facial
fractures (also see Chapter 17).
■ Fractures involving optic canal result in traumatic optic neuropathy. In
orbit trauma, optic traumatic neuropathy may occur even in absence of
direct impingement of the optic nerve.
■ Imaging ndings including presence of soft tissue/fat stranding around
the optic nerve in the optic canal.
6
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