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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4416_Библиотеки_им_академика_М_И_Перельмана
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Section 2 Inammatory Nasal Conditions82
Table 5.2: Types of choanal polyps.
Extension
Sl No Types Sinus of origin
1. Antrochoanal Maxillary sinus
(antrum)
2. Sphenochoanal Sphenoid sinus Sphenoid ostium Sphenoethmoidal
3. Ethmoidochoanal Ethmoid (posterior
ethmoids)
Bulla ethmoidalis
through Extension to
Maxillary
infundibulum/
accessory ostium
– Choana
Middle meatus
and then to
posterior choana
recess and then to
choana
■ Types:
• e common types include antrochoanal, sphenochoanal and
ethmoidochoanal (detailed in Table 5.2). e rare varieties are
septochoanal (from the nasal septum) and those from the lateral wall
of nose.
1,3
Antrochoanal Polyp
■ It is a subtype of polyp with a classical radiographic appearance and seen
usually in young adults.
■ ought to develop from blocked mucous glands in the maxillary sinus
forming retention cyst which enlarges and lls the maxillary sinus
protruding through ostium into the nasal cavity. e mucous glands
rupture resulting in inammation. is chain of events occurs as a
consequence of healing of acute sinusitis.
■ Imaging: Unilateral, solitary lesions that extends from the maxillary
sinus, through an expanded ostium (primary or accessory) into nasal
cavity and nasopharynx (Figs. 5.6 and 5.7).
■ Dierential diagnosis:
Inverted papillomas: Both entities look similar on NCCT. e key
dierentiating points are enlisted in Table 5.3.
Table 5.3: Key dierentiating features between a
antrochoanal and inverted papilloma.
Sl No Key feature Antrochoanal polyp Inverted papilloma
1. Calcication Rare Characteristic but seen only in
10%
2. Focal hyperostosis Not seen Characteristic
3. Pattern of
enhancement
4. Site of origin Maxillary sinus, hence
Peripheral/layered Cerebriform
Lateral nasal wall near middle
lls sinus and extends
through ostium
turbinate
BA
Figs. 5.6A and B: Antrochoanal polyp NCCT. (A) Soft tissue density mass left maxillary
antrum and nasal cavity (asterisk); and (B) Widening of ostium (arrow).
83Chapter 5 Imaging in Polyps and Mucoceles
A
B
Figs. 5.7A to C: Antrochoanal polyp MRI.
Polypoidal mass arising from right maxillary
antrum, widening ostium and extending into
nasal cavity and posterior choana. (A) T1
intermediate to hypointense (arrowhead), (B)
T2 hyperintense (asterisk) with hypointense
linear areas (arrow) (C) Intense enhancement
with non enhancing linear areas (brotic part/
C
desiccated secretions) (arrow).
Section 2 Inammatory Nasal Conditions84
BA
Figs. 5.8A and B: Ethmoidochoanal polyp. (A) Expansile (arrow) polypoidal mass right
ethmoidal cells, nasal cavity, choana; (B) Mass is enhancing (arrow) with non-enhancing
hypodense retained secretions in sphenoid sinus (asterisk).
Sphenochoanal Polyp
■ Rare unilateral lesion which arises from the sphenoid sinus, extends
through the sphenoid ostium into the sphenoethmoidal recess and then
to choana.
■ In the nasal cavity, it is seen to lie between the middle turbinate and nasal
septum. is space, which is located medial to the middle turbinate, is
not involved in antrochoanal polyp.
3
Ethmoidochoanal Polyps
■ Seen in young adults.
■ Unilateral, expansile solitary lesions which extend from the ethmoid
sinuses into nasal cavity and nasopharynx (Figs. 5.8A and B).
RETENTION CYSTS
■ Synonym: Intramural sinus cyst.
■ Retention cyst (RC) may result from obstruction of serous or
mucinous glands following inammation. e contents may hence be
predominantly serous or mucinous.
■ ough these are nonsecreting cysts, they may enlarge enough to ll the
sinus.
■ Common nding seen in patients with CRS/as an incidental nding in
asymptomatic individuals. Seen in almost 10% of healthy population.
■ Maxillary sinus is the most common site followed by the sphenoid sinus.
■ ere are two types of retention cysts: (1) mucous and (2) serous.
3,4
1
B CA
Figs. 5.9A to C: Retention cyst. (A) Well dened low density lesion along sinus wall (arrow);
Outer margin is convex; (B) T1WI: Hypointense (arrow); and (C) T2WI: Hyperintense (arrow).
• Mucous form: Consequent to accumulation of mucous following
obstruction of submucosal mucinous gland.
• Serous form: Due to collection of uid in the submucosa.
• Both forms appear similar on imaging.
■ Imaging (Figs. 5.9A to C):
• CT: Appears as well-dened, low-density lesion along the sinus wall
with convex, outer margin.
• MRI: Low signal intensity on T1WI, and bright on T2WI.
85Chapter 5 Imaging in Polyps and Mucoceles
SINONASAL ANGIOMATOUS POLYP SAP OR
SINONASAL ORGANIZED HEMATOMA
■ Rare benign entity, referred to by various terms over the years.
■ Synonyms: Sinonasal organized hematoma (SOH), pseudotumor,
cavernous hemangioma, and cholesterol granuloma.
■ Currently all these terms are thought to refer to the same/similar entities.
■ Most common site: Maxillary sinus, medially near ostium.
■ Age group: 20–40 years, can occur in children also.
■ Pathogenesis: ere are several hypotheses, two commonly proposed
theories are:
• When nasal polyps protrude through the maxillary ostium into the
maxillary sinus, due to compression of the pedicle of the polyp there
is vascular compromise. is leads to stasis, consequent edema
and ischemia. Ischemia leads to venous infarction and subsequent
neovascularization (SAP) and then brosis.
• Formed due to development of a brous capsule around a hematoma
(SOH). e brous capsule prevents resorption of the hematoma with
SAP and recurrent hemorrhages within the lesion.
• If cholesterol crystals deposit within the hematoma—resultant lesion
is a “cholesterol granuloma”.
Section 2 Inammatory Nasal Conditions86
BA
Figs. 5.10A and B: Sinonasal angiomatous polyp NCCT. (A) Mixed density, expansile
lesion in right maxillary sinus and nasal cavity (arrow); and (B) Smooth demineralization of
turbinates (asterisk) and lateral nasal wall.
• Factors predisposing to hematoma: Trauma, postsurgical, vascular
lesions, coagulation disturbance or frequent nasal bleeds. Hence,
common to both the entities is the neovascularization.
■ Most common presentation: Recurrent epistaxis. Others: cheek swelling.
■ Imaging: Reects the numerous components of the lesion, i.e. soft tissue
with hemorrhage in dierent stages, neovascularization with vascular
proliferation and brosis.
5
■ Computed tomography:
• NCCT (Figs. 5.10A and B): Mixed density/hyperdense on NCCT,
expansile, smooth demineralization of bones especially uncinate
process. Calcication: common.
• Contrast-enhanced computed tomography (CECT): Characteristic
papillary/frond like pattern of enhancement.
■ MRI (Figs. 5.11A to C):
• T1WI: Intermediate signal intensity (SI) with hyperintense foci.
• T2WI: Heterogenous, surrounded by a hypointense rim (brous
capsule). e magnetic resonance (MR) appearance is similar to
polyps, however peripheral hypointense rim on T2WI is more con sistently seen because of the brous capsule.
• CEMRI: Hypointense linear septae which do not show enhancement.
■ Dierential diagnosis:
• Malignant mass: e bony changes in malignancy are more erosive
with less expansion of the sinus.
• Antrochoanal polyp: SAP/SOH show more locally aggressive behavior
(bone erosion). Also polyps appear more hypodense, while SAP/SOH
is frequently hyperdense.
87Chapter 5 Imaging in Polyps and Mucoceles
A
C
B
Figs. 5.11A to C: Sinonasal angiomatous
polyp. (A) Well circumscribed T1 hypointense
heterogenous lesion in right maxillary sinus
and nasal cavity (black arrow); (B) Mass
shows T2 intermediate signal intensity with
T2 hypointense rim (arrow); and septa; (C)
Lobular enhancement (asterisk) with no
enhancement of the hypointense areas.
Obstructive sinusitis in right maxillary sinus
MUCOCELE
■ Meaning: “Collection of the mucous”. It is the most common expansile
sinus “mass”.
■ Common location: Frontal sinuses (approximately two-thirds); then
ethmoids; with maxillary and sphenoid sinus involvement being
infrequent.
■ Obstruction of the drainage pathway of a sinus leads to accumulation of
the secretions with marked expansion of the sinus. e lining is secretory
respiratory columnar epithelium.
■ Conned to a single sinus and in case a septum is present, then to a
compartment of the sinus. May even occur within variants such as
pneumatized anterior clinoid process, an Onodi cell or even in concha
bullosa.
■ Causes: Inammatory, traumatic, repeated surgeries, and tumors (such
as ossifying broma or brous dysplasia).
■ Clinical presentation is due to compression of the adjoining structures,
optic nerve compression can result in diminution of vision.
2
Section 2 Inammatory Nasal Conditions88
Fig. 5.12: Frontal mucocele (Water’s view). Opacication with expansion of left frontal
sinus (arrow).
■ Imaging:
2,3
• Plain radiographs reveal opacication of the sinus with expansion,
often marked (Fig. 5.12).
• CT: e expanded sinus contains secretions and is hence hypodense/
isodense to brain parenchyma and homogenous. Appears hyperdense
if inspissated secretions. Peripheral calcication may be seen.
• Cause slow expansion with remodeling of the sinus walls and there
may be scalloping of the adjoining borders (Figs. 5.13A and B).
• Usually there is thinning and deossication of sinus walls, but
uncommonly they may show a more aggressive behavior with bone
destruction and intracranial/orbital extension. Focal areas of lysis or
large defects may be seen.
• In frontal mucocele, the intactness of the posterior wall is critical to
evaluate (Fig. 5.14).
• Wall erosion may be seen in sphenoid mucocele particularly when
associated with a mycetoma. A concurrent mycetoma should be
BA
Figs. 5.13A and B: Sphenoid mucocele. (A) Expansion of right sphenoid sinus with
hyperdense contents (arrow); (B) with thinning and scalloping of bony margins (black arrow).
Right sphenoethmoidal recess blocked by inammatory mucosal thickening (asterisk)
resulting in sphenoid mucocele.
89Chapter 5 Imaging in Polyps and Mucoceles
Fig. 5.14: Frontal Mucocele: posterior wall assessment. Expansion of left frontal sinus
with some internal ossied contents (ossifying broma) (asterisk). Deossication of the
posterior wall (arrow) and thickening of the anterior wall.
suspected in a mucocele in presence of central hyperdensity with
scattered (linear or round) calcications. MRI shows hypointense
signal on T2WI.
• MRI: Appearance of secretions on imaging (Figs. 5.15 and 5.16)
depends on the protein content of the secretions as detailed in
Chapter 4. Hence, they may give similar appearance to CRS or fungal
sinusitis.
• On contrast administration only the mucosal lining enhances giving
appearances of rim enhancement (vs tumors).
Section 2 Inammatory Nasal Conditions90
BA
Figs. 5.15A and B: Ethmoidal mucocele. Mucocele shows T1 (A) and T2 (B) hyperintense
signal intensity (arrow), obstructive right maxillary sinusitis (asterisk) shows intermediate SI
on T1WI and heterogenous, predominant hypointensity on T2WI (retained secretions).
BA
Figs. 5.16A and B: Large right frontal mucocele: extradural extension. Expansile lesion
right frontal sinus with blockage of frontonasal drainage pathway (asterisk), T1 hypointense
(A) and T2 hyperintense (B) contents; with buckling of gray white matter interface in right
frontal lobe (arrow).
• e intracranial (Figs. 5.16A and B)/orbital extension is also well
documented.
• On CT and MRI, it is important to look for the cause of the mucocele.
e drainage pathway of the obstructed sinus should be meticulously
reported. e cause may be inammatory mucosal thickening
(see Figs. 5.13A and B), post-traumatic and postoperative. ough less
freq uent, it is important to exclude a tumor (Figs. 5.17A to C) as a cause
for the obstruction. is may be challenging and requires contrast
91Chapter 5 Imaging in Polyps and Mucoceles
A
C
B
Figs. 5.17 A to C: Secondary Mucocele in
a case of Ossifying Fibroma (OF): Role of
MRI (A and B) CT: Expansion of left frontal
sinus with soft tissue density contents with
small internal ossic component (asterisk).
Distinction between tumor and mucocele
cannot be made. (C) MRI: Nonossied
component of the tumor is also well seen on
the T2WI: heterogeneous signal mass (arrow)
blocking the left frontal ostium. Peripheral
T2 hyperintensity on MRI represents the
secretions in the mucocele (arrowhead).
admini stration. In addition, both CT and MR should be reviewed
together.
2,3
■ Dierential diagnosis:
• Obstructed sinus: Obstruction with retained secretions in absence of
expansion
• Retention cysts: Borders are non-scalloped
• Tumors: Solid pattern of enhancement in tumors
• Cephaloceles: Skull-base defects with herniation of meninges/CSF
(cerebrospinal uid).
LARGE AIRFILLED SINUSES
■ Pneumatization of the sinuses is variable and occasionally large air-lled
sinuses may be seen. is condition has been most frequently described
for frontal sinus. While it may be a normal variant, it may also result
from ball valve mechanism (partial obstruction of frontal sinus drainage
pathway due to mucosal edema), or even following the spontaneous
drainage of a mucocele. e various terms used are:6
• Pneumosinus/hypersinus: Large frontal sinus (normal variant).
• Pneumosinus dilatans: Abnormal expansion of the sinus which
encroaches on the surrounding structures. e sinus walls are however
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