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Computed tomography of sphenoid sinus tumors
Computed Tomography of Sphenoid Sinus Tumors Robert A. Zimmerman, M.D. Larissa T. Bilaniuk, M.D.
MATERIAl,
Departmentof Radiology,
Forty cases ofsphenoid sinus tumors that occurred in a series o f 4,700 consecu tire CT sea ns were reviewed (Tab}e l). These tumors were divided according to their origin: 1) primary and remote secondary sphenoid sinus tumors, 2) nasopharyngeal and paranasal sinus tumors, 3) intracranial tumors (Figure 2).
Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
INTRODUCTION Computed tomography (CT) accurately delineates the sphenoid sinus and its relationship to the rest of the cranial base, cranial tbssae, nasopharynx and orbits. Thus, the extent of a sphenoid sinus lesion can be clearly demonstrated. Superoinferior delineation is obtained by analyzing multiple adjacent sections. CT characterizes the lesions as to density, homogeniety and association of bony changes. This aids in the differential diagnosis.
INTERPRETATION AND DIFFERENTIAL DIAGNOSIS Sphenoid sinus lesions are identified by recognition of partial or complete replacement of the pneumatized portion of the sphenoid sinus (Figure 3). A possible pitfall in this diagnosis is asymmetric pneuntatization of the sphenoid sinus (Figure 4). Computed tomography not only identifies the lesion, but characterizes its density. Figure 5 shows an example of a
TECHNIQUE All examinations were performed on the EMI CT head scanner with a 160 x 160 matrix. All images were analyzed on the diagnostic display console with a wide window capability. This window encompasses a wide spectrum of density, which reveals optimum bone and soft tissue detail. Areas ot" contrast enhancemerit and small calcifications are still best evaluated with a narrower window. Anatomic relationships of the sphenoid bone dentonstrated on computed tomograms depend on the attgle of the plane of section (Figure 1). The anterior relationships are best shown on planes paraIlel to the orbitomeatal line (Fig. ID). whereas posterior relationships are best demonstrated on planes angled 20 degrees to the orbitomeatal line (Figure I, A, B and C). Requesls )br reprims should bc ;Jddrcssed to: Dr. Robert A. Zimmcrman, M.D.. Depanmem of Radiolugy. Hospital of the University of Pennsylvania, J400 Spruce Street. Philadelphia. Pennsylvania 19104. (Telephone: 2[5 602-30370 computila Axii! Tomogr Copyr,gh! ~ Umversay Parr Press, 1977 VOL 1, NO. 1, Prmtecl =nU.S.A.
Table 1. Classification of sphenold sinus tumors to origin
Primary and remote secondary tumors Chondrosarcoma Plasmocytoma Ossifying flbroma Metastases
according 6 2 1 2 1
Nasopharyngeal and paranasal sinus tumors Carcinomas Sarcomas Lymphomas Anglofibromas
~4 5 5 2 2
Intracranial tumors Meninglomas Chromoghobe a d e n o m a s a Neurinomas b Chordomas
20
Total
40
6 7
3 4
aOnly those tumors are included that have CT demonstration of sphenoid sinus involvement. ~ ot these were in patients with neurofibromatosis.
CT of Sphenoid Sinus Tumors 23
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~.; ~.:.: : . .
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Figure 1. Normal, Line drawing, top: median sagittal section with planes of computed tomographic scans (A-DJ indicated. A: high 20-degree section; B: mid 0-degree section; C: low 20-degree section; D: mid 20-degree section. 1: anterior cranial lossa; 2: globe; 3: orbit; 4: ethmoid sinuses; 5: maxillary sinus; 6: nasopharynx; 7: anterior crinoid process; 8: dorsum setiae; 9: sphenoid sinus; 10: middle cranial fossa; 11: clivus; 12: petrous bone; 13" posterior cranial fossa.
Zimmerman and Bilaniu~ 24
i9 Figure 2. Diagram of frontal section of sphenoid sinus with origin of tumors indicated, 1: primary and remote secondary sphenoid s)nus tumors; 2: nasopharyngeal and paranasal sinus tumors; 3: intracranial tumors.
Figure 3. Chromophobe adenoma. A 50.year.old male with panhypopituitarism. A: CT demonstrates a round expansile mass within the sella turcica; B: tower CT section shows the inferior extent of the lesion (arrow) inlo the sphenoid sinus.
CT of Sphenoid Sinus Tumors 25
Figure 4. Asymmetric pneumatization of sphenoid sinus. Left sphenoid sinus is I~ypopneumatized, consisting of a small air cell.
B Figure 5. Plasmocytoma. A 55-year-old female with renal disease clue to multiple myeloma. A: lateral tomogram of the midsaggital plane shows a soft tissue mass within the sphenoid sinus and bone destruction inferiorly and posteriorly (arrows); B: CT demonstrates a sphenoid sinus mass and clival destruction (arrow).
Zimmerman ancl Bilanluk 26
P,
Figure 6. Ossifying fibroma. A 14-year-old male with sudden left blindness. A: lateral toentgenogram reveals expanded opacified sphenoid sinus with destruction of the floor of the sella turcica. Two ttfin curvillineat calcifications (arrows) are present superiorly. B: CT scan shows a large, expansile, diffusely dense, sharply marginated sphenoid sinus mass. C: tower CT scan demonstrates inferior extent of the mass into nasopharynx and right maxillar sinus.
B
lesion of the sanle density as the soft tissues of the head. In contrast to this. Figure 6 shows a diffusely dense lesion. The presence of two additional changes in this case. expansion and margination, led to the correct histologic diagnosis of a sphenoid ossiffing fibroma. The use of density as an aid in histologic diagnosis is further exemplified by a case of ehondrosarcoma (Figure 7). Stippled calcification identified within an enlarged opacified sphenoid sinus indicates a tumor of cartilaginous origin. Demonstration of bone destruction, as in a case of lymphoma (Figure 8). is a sign of a more aggressive tumor. This is an important CT contribution to tumor diagnosis since conventional pluridirectional tomography may not reveal bone destruction because of loss of the usual airbone contrast. This is exemplified by a case of "histiocytic lymphoma where there was such marked opacifieation of the ethmoid sinuses that orbital invasion was not appreciated (Figure 9). |ntracranial (Figure 10), intraorbital, retronasopharyogeal and facial soft tissue involvement, not well appreciated by other radiographic modalities, is clearly shown by computed tomography. This inlbrmation is of importance both to the surgeon and radiotherapist. There are lesions that may mimic sphenoid sinus tumors. These most often are sinusitis, post-traumatic changes and aneurysms. In these instances, detection of bony abnormalities is of utmost importance in differential diagnosis. Sinusitis produces opacification, but usually no bone destruction (Figure IlL CT of Sphenoid Sinus Tumors 27
B
Figure 7. Sphenoid chondrosarcoma. A 53-year-old female in coma. A: lateral skull radiograph shows poorly delineated sphenoid sinus mass. Calcifications are present, but their exact location is uncertain. B: CT demonstrates an expansile mass (arrowheads) with stippled calcifications.
Zlmmerman and Bilaniuk 28
Figure 8. Lymphocytic lymphoma. A 33-year-olcl male with right proptosis. A: CT demonstrates a tumor involving the sphenoid and ethmoid sinuses. Bone destruction indicates sites of invasion into right orbit and middle cranial fossa. B: CT scan at a lower level shows tumor in both maxillary sinuses, nasal cavity and nasopharynx. Bone desgruction involves both medial maxillary sinus walls, as well as the cranial base.
Figure 9. Hlstlocytic lymphoma. A 73-year-old female with sudden loss of vision, right eye. A: fror~(=l tomographic section snows a right maxillary and sphenoid sinus mass. Orbital invasion is not demonstrated. B: CT shows a mass involving the right sphenoid and ethmoid sinuses. Bone destruction (arrow) of lateral wall of ethmoid sinus indicates site of orbital invasion. C: CT scan at a lower level shows involvement of the right maxillary sinus. Tumor extends into the nasal cavity through an area of bone destruction in the medial wall of the maxillary sinus (arrow).
CT of Sphenoid Sinus Tumors 29
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.- ,.~
:.J
~i~';:.: ~,: :.. :="'...-.f~~.:,.. ,?~ j,..,., ;,
~,,:'
. .
"
: : !.
Figure 11. Sphenoid sinusitis. CT scan shows opaclfication of left sphenoid sinus associated with thickening of the walls.
B
Figure 10. Cavernous sinus meningloma. A 72-year-old female with proptosis and blindness. A: base skull roentgenogram shows hyperostosis of sphenold sinus margin and opaclficatlon of right sphenoid sinus, B: CT demonstrates a contrast.enhanced mass having both an tntrasphenoidal and intracranial component (arrows). Hyperostosis of sphenoid sinus wall is present on right.
Zimmerman and Bilaniuk 30
Anet~rysms may smoothly erode the cranial base and sphenoid walls (Figure 12). Trauma is characterized by air.fluid levels or opacification, and by fractures of the osseous walls (Figure 13). Peripheral calcilication and prominent homogeneous enhancement help in the diagnosis of an aneurysm. Close attention should be paid to the clinical history and physical findings as well as conventional radiographs, since CT alone at times may not differentiate between these conditions and tumors.
CONCLUSIONS
Figure 12. Aneurysm internal cartoid artery. A 15-year-old male with right retro-orbital pain. A: base tomogram shows
smoothly marginated parasphenoidal erosion (arrowheads) and a process encroaching on the sphenoid sinus; B: CT demonstrates findings identical to base tomogram; C: lateral righi Internal carotid arteriogram demonstrates a large fuslform aneurysm of the lntracavernous portion
of the carotid artery.
Computed tomography plays an important role in the identification and delineation of sphenoid sinus tumors. The examination is noninvasive, fast and accurate. This is important in the case of the critically ill patient. It frequently reveals changes in more detail than a combination of plain radiographs and conventional tomography. Often there is adequate demonstration of intracranial components so that more invasive procedures such as arteriography and pneumoencephalography are not needed. Also. it entails a lower dose of radiation than the other procedures (1,2). CT of Sphenoid Sinus Tumors 31
Figure 13. Trauma. CT Shows an air.blood level in the sphenold sinus (arrow). Pneumocephalus underlies a temporal fracture on the right (arrowhead).
REFERENCES 1. Perry BJ, Bridges C: Computerized transverse axial scanning (tomography). Part 3. Radiation dose consideration. Br J Radiol 46:1048-1051. 1973 2. Dahlin H, Nylen O, Wilbrand H: Radiation dose distribution in temporal bone tomography. Acta Radiol 14: 353-367, 1973
CONTINUING MEDICAL EDUCATION QUESTIONS (COMPUTED TOMOGRAPHY OF SPHENOID SINUS TUMORS) 1.
Select and indicate the most incorrect statement regarding computed tomography (CT) of sphenoid sinus lesions. a. CT examination may preclude the need for pneumoencephalography. b. CT examination precludes the need for attention to history, physical findings and plain skull radio. graphs. c. The radiation burden on the patient being evaluated may be kept at a minimum by application of CT techniques. d. CT examination may preclude the need for cerebral angiography.
2.
Select and indicate the one most correct statement. a. Inflammatory sphenoid sinusitis usually produces smooth erosion of the wall rather than frank bone destruction. b. All the anatomic relationships of the sphenoid sinus are best delineated on CT scan planes parallel to the orbitomeatal line. c. Contrast enhancement has no merit in the evaluation of lesions of the sphenoid sinus. d. The presence of zn air fluid level is more suggestive of a traumatic than of a neoplastic etiology.
3.
Select and indicate the one most incorrect statement. a. CT may demonstrate orbital invasion by tumor that is not apparent on conventional tomography. b. Delineation of the extent of tumor is important to both surgeon and radiotherapist. c. The possibility of intracranial extension of a primary sphenoid sinus lesion restricts the clinical usefulness of CT. d. Careful analysis of CT images should include evaluation of specific areas with a relatively narrow window.
4.
Select the one neoplasm involving the sphenoid sinus that is not likely to be classified as a nasopharyngeal or paranasal sinus tumor. a. Carcinoma b. Chordoma c. Angiofibroma d. Sarcoma
Zimmerman and Bilaniuk 32
MATERIAl,
Departmentof Radiology,
Forty cases ofsphenoid sinus tumors that occurred in a series o f 4,700 consecu tire CT sea ns were reviewed (Tab}e l). These tumors were divided according to their origin: 1) primary and remote secondary sphenoid sinus tumors, 2) nasopharyngeal and paranasal sinus tumors, 3) intracranial tumors (Figure 2).
Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
INTRODUCTION Computed tomography (CT) accurately delineates the sphenoid sinus and its relationship to the rest of the cranial base, cranial tbssae, nasopharynx and orbits. Thus, the extent of a sphenoid sinus lesion can be clearly demonstrated. Superoinferior delineation is obtained by analyzing multiple adjacent sections. CT characterizes the lesions as to density, homogeniety and association of bony changes. This aids in the differential diagnosis.
INTERPRETATION AND DIFFERENTIAL DIAGNOSIS Sphenoid sinus lesions are identified by recognition of partial or complete replacement of the pneumatized portion of the sphenoid sinus (Figure 3). A possible pitfall in this diagnosis is asymmetric pneuntatization of the sphenoid sinus (Figure 4). Computed tomography not only identifies the lesion, but characterizes its density. Figure 5 shows an example of a
TECHNIQUE All examinations were performed on the EMI CT head scanner with a 160 x 160 matrix. All images were analyzed on the diagnostic display console with a wide window capability. This window encompasses a wide spectrum of density, which reveals optimum bone and soft tissue detail. Areas ot" contrast enhancemerit and small calcifications are still best evaluated with a narrower window. Anatomic relationships of the sphenoid bone dentonstrated on computed tomograms depend on the attgle of the plane of section (Figure 1). The anterior relationships are best shown on planes paraIlel to the orbitomeatal line (Fig. ID). whereas posterior relationships are best demonstrated on planes angled 20 degrees to the orbitomeatal line (Figure I, A, B and C). Requesls )br reprims should bc ;Jddrcssed to: Dr. Robert A. Zimmcrman, M.D.. Depanmem of Radiolugy. Hospital of the University of Pennsylvania, J400 Spruce Street. Philadelphia. Pennsylvania 19104. (Telephone: 2[5 602-30370 computila Axii! Tomogr Copyr,gh! ~ Umversay Parr Press, 1977 VOL 1, NO. 1, Prmtecl =nU.S.A.
Table 1. Classification of sphenold sinus tumors to origin
Primary and remote secondary tumors Chondrosarcoma Plasmocytoma Ossifying flbroma Metastases
according 6 2 1 2 1
Nasopharyngeal and paranasal sinus tumors Carcinomas Sarcomas Lymphomas Anglofibromas
~4 5 5 2 2
Intracranial tumors Meninglomas Chromoghobe a d e n o m a s a Neurinomas b Chordomas
20
Total
40
6 7
3 4
aOnly those tumors are included that have CT demonstration of sphenoid sinus involvement. ~ ot these were in patients with neurofibromatosis.
CT of Sphenoid Sinus Tumors 23
",v~,.-".
: , -'~'~ +
.,- ....
"--.~.~".:..,.
O---'-'---~.L;,., :. ~ ' g"
~
mulk. ~
l
~
:': ~,:.;,,~G,~i'~
~.; ~.:.: : . .
~": :
:'.:~
"
"~
::~
"!~
;.l'~""
Figure 1. Normal, Line drawing, top: median sagittal section with planes of computed tomographic scans (A-DJ indicated. A: high 20-degree section; B: mid 0-degree section; C: low 20-degree section; D: mid 20-degree section. 1: anterior cranial lossa; 2: globe; 3: orbit; 4: ethmoid sinuses; 5: maxillary sinus; 6: nasopharynx; 7: anterior crinoid process; 8: dorsum setiae; 9: sphenoid sinus; 10: middle cranial fossa; 11: clivus; 12: petrous bone; 13" posterior cranial fossa.
Zimmerman and Bilaniu~ 24
i9 Figure 2. Diagram of frontal section of sphenoid sinus with origin of tumors indicated, 1: primary and remote secondary sphenoid s)nus tumors; 2: nasopharyngeal and paranasal sinus tumors; 3: intracranial tumors.
Figure 3. Chromophobe adenoma. A 50.year.old male with panhypopituitarism. A: CT demonstrates a round expansile mass within the sella turcica; B: tower CT section shows the inferior extent of the lesion (arrow) inlo the sphenoid sinus.
CT of Sphenoid Sinus Tumors 25
Figure 4. Asymmetric pneumatization of sphenoid sinus. Left sphenoid sinus is I~ypopneumatized, consisting of a small air cell.
B Figure 5. Plasmocytoma. A 55-year-old female with renal disease clue to multiple myeloma. A: lateral tomogram of the midsaggital plane shows a soft tissue mass within the sphenoid sinus and bone destruction inferiorly and posteriorly (arrows); B: CT demonstrates a sphenoid sinus mass and clival destruction (arrow).
Zimmerman ancl Bilanluk 26
P,
Figure 6. Ossifying fibroma. A 14-year-old male with sudden left blindness. A: lateral toentgenogram reveals expanded opacified sphenoid sinus with destruction of the floor of the sella turcica. Two ttfin curvillineat calcifications (arrows) are present superiorly. B: CT scan shows a large, expansile, diffusely dense, sharply marginated sphenoid sinus mass. C: tower CT scan demonstrates inferior extent of the mass into nasopharynx and right maxillar sinus.
B
lesion of the sanle density as the soft tissues of the head. In contrast to this. Figure 6 shows a diffusely dense lesion. The presence of two additional changes in this case. expansion and margination, led to the correct histologic diagnosis of a sphenoid ossiffing fibroma. The use of density as an aid in histologic diagnosis is further exemplified by a case of ehondrosarcoma (Figure 7). Stippled calcification identified within an enlarged opacified sphenoid sinus indicates a tumor of cartilaginous origin. Demonstration of bone destruction, as in a case of lymphoma (Figure 8). is a sign of a more aggressive tumor. This is an important CT contribution to tumor diagnosis since conventional pluridirectional tomography may not reveal bone destruction because of loss of the usual airbone contrast. This is exemplified by a case of "histiocytic lymphoma where there was such marked opacifieation of the ethmoid sinuses that orbital invasion was not appreciated (Figure 9). |ntracranial (Figure 10), intraorbital, retronasopharyogeal and facial soft tissue involvement, not well appreciated by other radiographic modalities, is clearly shown by computed tomography. This inlbrmation is of importance both to the surgeon and radiotherapist. There are lesions that may mimic sphenoid sinus tumors. These most often are sinusitis, post-traumatic changes and aneurysms. In these instances, detection of bony abnormalities is of utmost importance in differential diagnosis. Sinusitis produces opacification, but usually no bone destruction (Figure IlL CT of Sphenoid Sinus Tumors 27
B
Figure 7. Sphenoid chondrosarcoma. A 53-year-old female in coma. A: lateral skull radiograph shows poorly delineated sphenoid sinus mass. Calcifications are present, but their exact location is uncertain. B: CT demonstrates an expansile mass (arrowheads) with stippled calcifications.
Zlmmerman and Bilaniuk 28
Figure 8. Lymphocytic lymphoma. A 33-year-olcl male with right proptosis. A: CT demonstrates a tumor involving the sphenoid and ethmoid sinuses. Bone destruction indicates sites of invasion into right orbit and middle cranial fossa. B: CT scan at a lower level shows tumor in both maxillary sinuses, nasal cavity and nasopharynx. Bone desgruction involves both medial maxillary sinus walls, as well as the cranial base.
Figure 9. Hlstlocytic lymphoma. A 73-year-old female with sudden loss of vision, right eye. A: fror~(=l tomographic section snows a right maxillary and sphenoid sinus mass. Orbital invasion is not demonstrated. B: CT shows a mass involving the right sphenoid and ethmoid sinuses. Bone destruction (arrow) of lateral wall of ethmoid sinus indicates site of orbital invasion. C: CT scan at a lower level shows involvement of the right maxillary sinus. Tumor extends into the nasal cavity through an area of bone destruction in the medial wall of the maxillary sinus (arrow).
CT of Sphenoid Sinus Tumors 29
.,.- ~?.:.: . . .
.- ,.~
:.J
~i~';:.: ~,: :.. :="'...-.f~~.:,.. ,?~ j,..,., ;,
~,,:'
. .
"
: : !.
Figure 11. Sphenoid sinusitis. CT scan shows opaclfication of left sphenoid sinus associated with thickening of the walls.
B
Figure 10. Cavernous sinus meningloma. A 72-year-old female with proptosis and blindness. A: base skull roentgenogram shows hyperostosis of sphenold sinus margin and opaclficatlon of right sphenoid sinus, B: CT demonstrates a contrast.enhanced mass having both an tntrasphenoidal and intracranial component (arrows). Hyperostosis of sphenoid sinus wall is present on right.
Zimmerman and Bilaniuk 30
Anet~rysms may smoothly erode the cranial base and sphenoid walls (Figure 12). Trauma is characterized by air.fluid levels or opacification, and by fractures of the osseous walls (Figure 13). Peripheral calcilication and prominent homogeneous enhancement help in the diagnosis of an aneurysm. Close attention should be paid to the clinical history and physical findings as well as conventional radiographs, since CT alone at times may not differentiate between these conditions and tumors.
CONCLUSIONS
Figure 12. Aneurysm internal cartoid artery. A 15-year-old male with right retro-orbital pain. A: base tomogram shows
smoothly marginated parasphenoidal erosion (arrowheads) and a process encroaching on the sphenoid sinus; B: CT demonstrates findings identical to base tomogram; C: lateral righi Internal carotid arteriogram demonstrates a large fuslform aneurysm of the lntracavernous portion
of the carotid artery.
Computed tomography plays an important role in the identification and delineation of sphenoid sinus tumors. The examination is noninvasive, fast and accurate. This is important in the case of the critically ill patient. It frequently reveals changes in more detail than a combination of plain radiographs and conventional tomography. Often there is adequate demonstration of intracranial components so that more invasive procedures such as arteriography and pneumoencephalography are not needed. Also. it entails a lower dose of radiation than the other procedures (1,2). CT of Sphenoid Sinus Tumors 31
Figure 13. Trauma. CT Shows an air.blood level in the sphenold sinus (arrow). Pneumocephalus underlies a temporal fracture on the right (arrowhead).
REFERENCES 1. Perry BJ, Bridges C: Computerized transverse axial scanning (tomography). Part 3. Radiation dose consideration. Br J Radiol 46:1048-1051. 1973 2. Dahlin H, Nylen O, Wilbrand H: Radiation dose distribution in temporal bone tomography. Acta Radiol 14: 353-367, 1973
CONTINUING MEDICAL EDUCATION QUESTIONS (COMPUTED TOMOGRAPHY OF SPHENOID SINUS TUMORS) 1.
Select and indicate the most incorrect statement regarding computed tomography (CT) of sphenoid sinus lesions. a. CT examination may preclude the need for pneumoencephalography. b. CT examination precludes the need for attention to history, physical findings and plain skull radio. graphs. c. The radiation burden on the patient being evaluated may be kept at a minimum by application of CT techniques. d. CT examination may preclude the need for cerebral angiography.
2.
Select and indicate the one most correct statement. a. Inflammatory sphenoid sinusitis usually produces smooth erosion of the wall rather than frank bone destruction. b. All the anatomic relationships of the sphenoid sinus are best delineated on CT scan planes parallel to the orbitomeatal line. c. Contrast enhancement has no merit in the evaluation of lesions of the sphenoid sinus. d. The presence of zn air fluid level is more suggestive of a traumatic than of a neoplastic etiology.
3.
Select and indicate the one most incorrect statement. a. CT may demonstrate orbital invasion by tumor that is not apparent on conventional tomography. b. Delineation of the extent of tumor is important to both surgeon and radiotherapist. c. The possibility of intracranial extension of a primary sphenoid sinus lesion restricts the clinical usefulness of CT. d. Careful analysis of CT images should include evaluation of specific areas with a relatively narrow window.
4.
Select the one neoplasm involving the sphenoid sinus that is not likely to be classified as a nasopharyngeal or paranasal sinus tumor. a. Carcinoma b. Chordoma c. Angiofibroma d. Sarcoma
Zimmerman and Bilaniuk 32