Jane

L. Weissman,

MD

Ellen

#{149}

Sphenochoanal with CT and

A sphenochoanal mass

of low

polyp attenuation

K. Tabon,

and

into

the

is a solitary on

choana

from

the

more

common

choana

Index

terms: Nose, CI, 261.1211 #{149} Nose, MR studies, 261.1214 #{149} Nose, neoplasms, 261.369. Paranasat sinuses, CI, 23.1211 #{149} Pananasat sinuses, MR studies, 23.1214 #{149} Pananasal sinuses, neoplasms, 23.369 #{149} Paranasal sinuses, potyps, 23.369

Radiology

1991;

178:145-148

nasal

cavity

sometimes

Department

of Radiology,

Univer-

sity of Pittsburgh School of Medicine, Eye and Ear Hospital, 230 Lothrop St. Pittsburgh, PA 15213. Received July 9, 1990; revision requested August 14; revision received August 28; accepted September 4. Address reprint requests to H.D.C. ,c, RSNA, 1991

and

arises

from

between

the

tion tion not

the

must

be nesected

nence,

and

pends

on

arises and excavity into of each of

surgical

the

target

a recur-

approach

de-

sinus.

CASE REPORTS SPHENOCHOANAL

is

OF POLYPS

a completely sinus (Fig ia).

tended through the sphenoethmoid on

contiguous

sphenoid ostium into recess (Fig ib) and,

axial

sections,

could

be

fol-

bowed into the nasal cavity between the middle tumbinate and the nasal septum (Fig lc-le). The polyp widened the sphenoid

ostium

sinus rotic

was walls

(Fig

sinusitis. and the

turbinate

and

cavity

were

cluding

the

The

the

lateral

thickened

(Fig

maxillary

of the choanal The polyp was

id),

of the

polyp. resected

of the

nasal

findings

antrum

ex-

as the

on-

tmansnasalby

Microscopic

contents

scle-

indicating

wall

in

examination

night

sphenoid

of

sinus

and nasal cavity revealed chronic rhinosinusitis. Case 2.-A 43-year-old woman complained of recurrent sinusitis that was un-

relieved onal

CT

pleteby

extending posterior contained

with

sinus

scans

revealed

filling

the

through choana. thickened

lavage.

Axial

a polyp

left

its ostium The

left mucosa

and sinus

into

maxillary and

CT scans demonThere was a

the

small

polyp

of the

maxillary

The middle turbinate and a portion of the anterior wall of the sphenoid sinus were resected transnasabby. The sphenochoanal polyp was dissected free and debivered through the nasopharynx. The histologic diagnosis was inflammatory

sion

58-year-old

left

of the

to exclude

nus

reten-

effu-

CT

mass

ob-

(Fig

2b).

No

further

action

was

for this asymptomatic finding. Case 5.-A 61-year-old woman year history of night-side epistaxis. and

coronal

tissue. herniated

CT

nasal There

The

scans

revealed

sinus

the

sphenoid

the

mass

into

possible

the

sella,

had

a 1-

Axial

filled

anterior portion out of the ostium

and

taken

that

was

cavity and choana was also remodeling

most

with

soft

of the mass and into the

(Fig

3a, 3b). of the roof

extension which

raised

of of the

question of a neoplastic lesion. Tiweighted axial magnetic resonance (MR) images (Signa 1.5 1; GE Medical Systems) showed that the mass, which had an intermediate signal intensity, was constricted as it passed from the sinus through the sphenoid

ostium

and

into

3c, 3d). On 12-weighted of highest signal intensity

and

volving

sinus

with

ear underwent

structing the eustachian tube. No obstructing mass was present. A small polyp was incidentally identified in the right posterior pharynx (Fig 2a). The polyp extended up into the opaque sphenoid si-

or portion most likely

the

man

middle

a nasopharyngeal

con-

incom-

sphenoid

coronal palate.

of the sphenoid

maxillary

However, the middle space between the middle

clear

pieces.

right

and had ic), findings

opaque (Fig

chronic meatus

if).

resecbut has

sphenochoanal polyp with a large choanal component. The choanal portion was interposed between the nasal septum and the medial aspect of the medial ptenygoid plate. The middle meatus was clear, and the choanal polyp was clearly sepa-

Case 4.-A

opaque right spheA soft-tissue mass ex-

the

endoscopic scheduled

pobyps.

Case 1.-An 11-year-old girl had a history of years of chronic sinusitis. Computed tomographic (CT) scans (GE 9800 unit; GE Medical Systems, Milwaukee) demonstrated noid

Axial and a normal

rate from sinus.

to docucomponent

to prevent

the

cyst.” strated

the

nasopharynx

is important the sinus

cysts. Transnasal of the polyp was yet been performed.

Case 3.-A 21-year-old woman was referred for further evaluation of a “pabatab

nasopharynx)

into

polyps because

the

the

boundary

these ment,

small

From

polyp

(1). An antrochoanal polyp from the maxillary antrum tends back along the nasal the choana (2). The origin

gin

I

Evaluation

(the

and

antro-

sinus.

MD

edematous, hypenplastic submucosa lining the wall of the sphenoid sinus, passes through the sinus ostium, and protrudes into the

(the

choanal polyp. The sinus of origin important to identify, as the surgical approach depends on the target

D. Curtin,

sphenochoanal

comput-

boundary between the nasal cavity and nasopharynx). More often, however, a choanal polyp is an antrochoanal polyp, which arises from the maxillary antrum, protrudes through the middle meatus, extends into the nasal cavity, and continues back to the choana. Contiguous axial or coronal magnetic resonance and CT images help clearly differentiate the rare sphenochoanal polyp

Hugh

#{149}

Polyps: MR Imaging’

ed tomographic (CT) scans that arises from the sphenoid sinus and extends through the sphenoid ostiurn, across the sphenoethmoid recess,

MD

and

of the mass. represented

a portion

causing

addition, of the

sinus

extended

arising

choana

The abnormality a mucocele

of the

remodeling

a polyp

the

(Fig

images, the area was the supeni-

sphenoid of the

bone.

in a separate through

in-

sinus

the

In

cell ostium

145

a.

b.

c.

d.

e.

f.

Figure

1. Case 1. (a-c) Sequential axial CT scans (soft-tissue algorithm). (a) Ihe sphenoid sinus is opaque (arrow). (b) A tow-attenuation soft-tissue mass extends into the sphenoethmoid recess (arrow). This portion of the polyp is in continuity with the mass in the might sphenoid sinus. (c) The polyp is seen in the posterior nasal cavity (arrow). The right maxillary sinus is also completely opaque, and its walls are thickened (arrowheads). (d) The sphenochoanal polyp (solid black arrow) extends between the nasal septum (s) and the middle tunbinate (large highlighted arrow). The middle meatus is clear (small highlighted arrow). (e) The inferior aspect of the sphenochoanal polyp is in the nasal cavity and choana (arrow). No connection between the polyp and the maxillary antmum could be demonstrated. (f) Coronal CT scan (bone algorithm). The sphenoid ostium (arrow) is widened by the polyp, which extends through the ostium from the sinus into the nasal cavity.

into

the

bility

sphenoethmoid

that

the

recess.

superior

aspect

was a neopbasm,

although

not

conclusively.

be

excluded

confirmation

geny was icat

is not

postponed

The

possi-

of the

mass

unlikely,

available

indefinitely

could

Histologic because

sum-

for med-

reasons.

DISCUSSION A polyp is a mass of the paranasal sinuses and is composed of edematous, hyperplastic submucosal connective tissue (3). Because polyps are relatively hypocellular, they are hypoattenuating on CT scans. Their interstitium contains benign stromal cells, a few mucus glands, and, rareby, eosinophils and lymphocytes. A choanal polyp is a solitary mass 146

Radiology

#{149}

of low attenuation. mon choanal polyp,

The the

most cornantrochoanal

polyp (Fig 4), originates within the maxillary sinus (antrurn). As an antral polyp enlarges, it protrudes through the middle meatus into the nasal cavity between the middle turbinate and the lateral wall of the nasal cavity. The polyp may then extend posteriorly toward the choana, the junction between the nasal cavity and the nasopharynx (Fig 4b). The polyp may also extend into the nasopharynx. A very large antrochoanal polyp may appear as a mass in the oropharynx (2,3). Although more rare, sphenochoanal polyps and ethmoidochoanal polyps have also been described (1). The first report of a sphenochoanal

polyp is generally attributed to Zuckerkandl (4). A sphenochoanal polyp develops from a polyp in the sphenoid sinus that enlarges and bulges through the sphenoid ostium. The ostium may constrict the polyp (Fig 3d), or the polyp may enlarge the ostium (Fig if). The location of the ostium along the anterior wall of the sinus varies (Fig 5). Consequently, the ostium may be identified on angled axial on coronal images or may not be clearly seen. The sphenoid ostium opens into the sphenoethmoid recess, which is high in the nasal cavity above and behind the superior tunbinate (Fig ib). From here, with further enlargement, the polyp herniates down into

January

1991

the

choana. If the sphenoid sinus is opaque and the maxillary sinus is clear, a choanal polyp is probably sphenochoanal, even if the connection cannot be clearly demonstrated. If both the maxillary antrum and the sphenoid sinus may

are opaque, be sphenochoanal

choanal. between

a choanal polyp on antro-

In this case, the continuity the polyp and the correct

nus of origin to document. In the case yp, the polyp

is especially of an antrochoanal can be followed

the middle meatus between the middle b. Figure

2. Case 4. Sequential axial CT scans (bone algorithm). (a) A small polyp (+) can be seen in the night posterior pharynx. There is residual opacity in several left mastoid aim cells (arrow), despite placement of a tympanostomy tube (not shown). (b) The polyp extends through the sphenoid ostium (o). Continuity between the nasal and sphenoid components of the polyp is apparent. This small polyp did not extend as far infeniomly and anteriorly as the choana, and a more precise designation for it therefore would be sphenonasal polyp.

(Fig 4b); turbinate

the lateral wall of the nasal contrast to a sphenochoanal the space between the nasal

and

the

middle

si-

important

tunbinate

polinto

it passes and cavity. polyp, septum

In

is clean.

With a sphenochoanal polyp, the polyp is between the nasal septum and the middle turbinate. Both the middle meatus and the space between the middle turbinate and the lateral wall of the nasal cavity are

clear. Definitive therapy of antrochoanal on sphenochoanal polyps involves mesection of the sinus component along with the choanal polyp. Although

avulsion of the choanal polyp (by means of snaring) is simpler, this technique is associated with a high frequency of recurrence (2). The Caldwell-Luc approach is one way

to resect

an

antrochoanal

polyp.

The maxillary sinus is entered through its anterior wall after an incision is made in the gingivolabial sulcus

(2).

The

base

of the

polyp

in

the maxillary antrum is removed, and the entire mass-including the choanal portion-may be delivered through the nose, the mouth, on the Caldwell-Luc incision. The anterior

b.

wall of the sphenoid sinus is not easily accessible through a Caldwell-Luc incision, however, and alternative approaches are used. Fibemoptic technology has greatly facilitated transnasal endoscopic sphenoid surgery (5,6). CT and MR imaging can help identify the continuity of the soft tissue

between opaque

a choanal polyp and the sinus in which it arises. An-

trochoanal

Sphenochoanal ally c. Figure

Volume

178

#{149} Number

1

are

polyps and

most

mass ostisigof

common.

are occasioncan

lowed from the posterior (between the nasal septum

d.

3. Case 5. (a, b) Sequential axial CT scans (soft-tissue algorithm). (a) A choanat is present (m). (b) The mass (m) extends superiorly in continuity toward the sphenoid um. (c, d) Sequential axial Ti-weighted MR images. (c) A polypoid mass of intermediate nab intensity (p) is in the posterior choana. (d) The mass (m) is constricted as it passes through the sphenoid ostium (arrow) into the sphenoid sinus (s). The signal intensities these two components of the mass are the same.

encountered

polyps

be fol-

nasal and

cavity the

middle turbinate), into the choana, across the sphenoethmoid recess, through the sphenoid ostium, and into the sphenoid sinus. Documentation of the sinus of origin is impor-

Radiology

#{149} 147

Figure scans

4.

Antrochoanal

enhanced

with

polyp. contrast

Axial material

tissue algorithm). (a) The antral (n), and choanal (c) components trochoanal polyp are all apparent. large maxillary antral polyp (P) ed through the sinus ostium (o) dle meatus, into the nasal cavity only

into

the

appearance

choana

(c).

This

of an antrochoanab

CT (soft-

(a), nasal of this an(b) A has extendand the midand posteri-

is the

typical

polyp.

a.

.

Sphenod

b.

tant,

as the

surgical

origin

approach.

may

influence

#{149}

the

References 1.

Figure

5.

Lateral

diagram

of the nasal

cavi-

ty and sphenoid sinus. The sphenoid ostium may be located anywhere along the anterior wall of the sinus (arrows). Inf. inferior.

148

Radiology

#{149}

2.

Hayes E, Layette W. Sphenochoanal potyp: CI findings. J Comput Assist Tomogn 1989; 13:365-366. Tobin HA. Surgery of the ma.xilla and mandible. In: Papanella MM, Shumnick DA, eds. Otolaryngology. Philadelphia: Saunders, i980; 2716-2757.

3.

4.

5.

6.

Barnes L, Verbin RS, Gnepp DR. Diseases of the nose, paranasal sinuses, and nasopharynx. In: Barnes L, ed. Surgical pathology of the head and neck. New York: Dekken, 1985; 403-451. Prusad U, Sagan P. Shahul Hameed 0. Choanat polyp. J Larnygol Otol 1970; 84:951-954. Wigand ME. Endoscopic surgery of the paranasal sinuses and anterior skull base. New York: Ihieme, 1990. Rice DH, Schaefer SD. Endoscopic paranasat sinus surgery. New York: Raven, 1988.

January

1991