1977, British Journal of Radiology, 50, 181-184
MARCH
1977
Bone thinning in frontal mucocele By A. R. Jackson, M.B., Ch.B., D.M.R.D., F.R.C.R. Wessex Neurological Centre, Southampton (Received August, 1976) ABSTRACT
Sixteen cases of frontal mucocele are reviewed. Bone thinning leading to destruction of the sinus floor was shown to be a feature. It usually affects the superomedial margin of the orbital roof first, due to pressure on the area where the sinus wall is thinnest. Demonstrable thinning of either anterior or posterior sinus walls—a cardinal sign of frontal mucocele, is best shown by means of underpenetrated lateral radiographs. All other conventional radiographic signs of frontal mucocele, including lucency of the affected sinus, were found to be non-specific. The presence of an osteoma in a site likely to obstruct the frontonasal duct is a valuable adjunct to diagnosis.
The radiographic lucency paradoxically shown in some frontal mucoceles is the result of a thinning of the walls of the sinus, which can be demonstrated by means of soft tissue lateral radiographs. Schworer et ah (1972) proved in experiments with models that the image cast by a fluid-filled cavity will be less dense if its walls are thin. An attempt is made in this paper to define the radiological profile of mucoceles of the frontal sinus and to outline differential diagnostic criteria in respect of other lesions. CASE MATERIAL AND FINDINGS
Sixteen cases of frontal mucocele from the Wessex Neurological Centre, Southampton and the Liverpool Ear, Nose and Throat Infirmary were studied. The commonest clinical presentation (13 out of 16
patients) was a painless and non-pulsating unilateral proptosis. In three patients the proptosis was severe enough to have produced double vision. Sinus pain was a prominent feature in only one patient (Case 15, Table I), and only two others complained of pain in the region of the eyes and forehead. In Case 6, a patient undergoing treatment for nasal polyp, the frontal mucocele was a chance finding. Standard radiographic views of the paranasal sinuses were available, including occipito-frontal, occipito-mental, and lateral projections. Several patients were also examined by tomography of the frontal sinuses. The radiological features are given in Table I. In the coronal views, the main finding was destruction of the supero-medial margin of the roof of the underlying orbit. Increased sinus opacity was present in nine patients, this appearance being consistent with a fluid-filled sinus. No fluid levels were seen. Of the remaining seven patients, three had hyperlucent frontal sinuses. Osteomata were seen in three patients, situated in sites considered likely to obstruct the frontonasal duct. Sclerosis of the bony margin of the affected sinus was present in five of the 16 patients. In lateral projections bone thinning was convincingly demonstrated in a total of nine patients; underpenetrated films showed it better.
TABLE I RADIOLOGICAL FEATURES OF 16 PATIENTS
181
Increased sinus density
Sclerotic margin + I+ I+ I I I I I+ I I+ I I
t
Osteoma
+ + I ++ I I + I ++ I ++ I I
Female, 58, Painless proptosis, diplopia Female, 53, Painless proptosis, diplopia Male, 79, Painless proptosis Male, 73, Painless proptosis Female, 60, Painless proptosis, diplopia Female, 36, Nasal polyp Female, 76, Painless proptosis Male, 75, Painless proptosis Female, 64, Painless proptosis Female, 56, Painless proptosis Male, 50, Pansinusitis Male, 56, Pain round eye, proptosis Male, 54, Painless proptosis Female, 46, Painless proptosis Male, 48, Pansinusitis Male, 46, Painless proptosis
+ I ++ I I + I I + + + I I + +
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Orbital erosion Bone thinning
I I I I I I I I I + I I + I I +
Cases
VOL.
50, No. 591 A. R. Jackson
FIG. 1. Right frontal mucocele-occipito-frontal and lateral projections. There is loss of the superior orbital" margin, the sinus is lucent. The lateral projection shows a sinus of small depth with a thinned anterior wall.
FIG. 2. Right frontal mucocele-occipito-frontal and lateral projections. Loss of the superior orbital margin, but a sinus of increased density. The lateral projection shows a sinus of increased depth.
182
MARCH 1977
Bone thinning in frontal mucocele TABLE II
present alone, or in the controls. The anteroposterior diameter of the control group varied widely, from 0.5 to 2.6 cm, averaging 1.2 cm. Bone thinning Bone thinning According to Gray (1973) the average diameter of with increased with lucent the frontal sinus is 1.8 cm. These measurements are opacity sinus Control group significantly lower than the average of the group 2.4 1.2 1.1 2.0 showing a combination of bone thinning and in2.7 1.4 2.3 0.9 creased opacity, namely 2.3 cm. The wide variation 2.2 1.6 0.7 0.9 in the control group confirms that it is impossible to 1.9 1.1 0.8 1.1 0.8 0.7 1.8 diagnose pathological antero-posterior expansion of 1.5 1.0 a sinus in any individual patient without the 0.8 0.9 benefit of serial radiographic examinations. 1.7 0.7 0.5 2.6 Loss of the normal sclerotic sinus margin is said 0.9 1.4 to be an early change in mucocele, which occurs prior to expansion of the sinus (Samuel, 1968), and the findings in nine patients confirm this. Loss of the The depth of the frontal sinus was measured in convoluted pattern of the affected sinus (Wolfowitz three groups (Table II): (1) cases of frontal mucocele and Solomon, 1972) and deviation of the intersinus exhibiting bone thinning and increased opacity of septum towards the unaffected side are also believed the sinus—four patients; (2) cases with frontal to be unreliable signs, unless confirmed by serial mucoceles exhibiting bone thinning and lucent or examinations. In life the frontal sinuses are usually hyper-lucent sinuses—five patients; and (3) a asymmetrical, and deviation of the intersinus septum randomly-selected control group—20 subjects. The is a common normal variant (Gray, 1973). findings (Table II) showed that a significantly Squamous carcinoma of the frontal sinus, a rare greater average sinus depth was present in the entity, may present the same pattern of destruction Group 1 patients than in the other groups. in coronal views as frontal mucocele (Boone and Harle, 1968), but the lateral projection is said usually to show early destruction of the walls, rather DISCUSSION Frontal mucocele accounts for 15% of the patients than the typical thinning exhibited by a mucocele. with unilateral exophthalmos presenting to an ear, Kriise and Neumann (1974), in a review of four cases nose and throat surgeon (Zizmor and Noyek, 1968) of sinus disease in which the diagnosis was in doubt, and 3% of those presenting to an ophthalmic surgeon claimed that surgical biopsy may be the only way of (Reese, 1963). Most authors (Wolfowitz and providing a definitive answer. Defects of cranial Solomon, 1972; Iliff, 1973) agree that pain is not a fusion such as meningocele and encephalocele of the feature of the condition. However, Bordley and frontal region in adults are said to mimic mucocele if Bosley (1973) found a high incidence of headache in the characteristic mid-line defect in the skull is not a series of cases which was notable for its high visible (Zizmor and Noyek, 1968). Plain-film changes, similar to a mucocele, were present in a complication rate. The characteristic radiological finding in this 23-year-old patient with an olfactory neuroblastoma series was destruction of the layer of bone separating who presented at the Wessex Neurological Centre the sinus from the orbit, which is the thinnest part with a short history of pain and proptosis. of the sinus wall (Cunningham, 1972). Consequently this is its weakest part and it will be affected first by ACKNOWLEDGMENTS an expanding lesion of the frontal sinus. I would like to thank Dr. E. H. Burrows for his helpful and criticism, and also Dr. R. W. Galloway for Thinning of the anterior and posterior sinus walls advice providing access to his cases at the Liverpool Ear, Nose and may be demonstrated in lateral projections—it was Throat Infirmary. present in nine of the 16 patients reviewed. If convincingly present, it represents a reliable sign of REFERENCES mucocele. BOONE, M. L. M., and HARLE, T. S., 1968. Malignant tumours of the paranasal sinuses. Seminars in RoentThe patients in whom a combination of bone genology, 3, 202-213. thinning and increased opacity was present, posses- BORDLEY, J. E., and BOSLEY, W. R., 1973. Mucoceles of the front sinus—causes and treatment. Annals of Otology, sed a greater average antero-posterior diameter of Rhinology and Laryngology, 82, 696—702. the frontal sinuses than was shown either in those CUNNINGHAM'S Textbook of Anatomy. 11 th ed. Edited by patients in whom one or other of these features was G. J. Romanes, London 1972 (Oxford University Press). DEPTH OF FRONTAL SINUS (CM)
183
VOL.
50, No. 591 A. R. Jackson
GRAY'S Anatomy. 35th ed. 1973 (Longman). Sinus depth 1.8p.1092. Deviation of septum - p.299. ILIFF, C , 1973. Mucoceles in the orbit. Archives of Ophthalmology, 89, 392-395.
paranasal sinuses. Seminars in Roentgenology, 3,148-159. SCHWORER I., GERSTENBERG, E., and KRAUSE, H. C , 1972.
Die Mukocele der Nasennebenhohle-ein Rontgendiagnotisches Problem? Fortschritte auf dem Gebiete der Rontgenstrohlen und der Nuklearmedizin, 117, 642-647.
KRUSE, C. G., and NEUMANN, O. G., 1974. Nasenneben-
hohlen-Mucocelen mit der Symptomatik Maligner WOLFOWITZ, B. L., and SOLOMON, A., 1972. Mucoceles of Tumoren. H.N.O. Wegweiser fur die Fagheerytliche the frontal and ethmoid sinuses. Journal of Laryngology Praxis, 22,195-197. and Otology, 86, 79-82. REESE, A. B. Tumours of the Eye. 2nd ed., 529-580. New ZIZMOR, J., and NOYEK, A. M., 1968. Cysts and benign York Hoeber Medical Division, Harper and Row. tumours of the paranasal sinuses. Seminars in Roentgenology, 3, 172-201. SAMUEL, E., 1968. Inflammatory diseases of the nose and
Book review Nuclear Medicine: Report of a joint I.A.E.A./W.H.O. expert committee on the use of ionizing radiation and radioisotopes for medical purposes (nuclear medicine). Technical Report Series 591, pp. 72, 1976 (World Health Organization, Geneva), Sw. Fr. 7. The title of this report is somewhat misleading, as it could be construed to include X-ray diagnosis and beam radiotherapy, whereas it is concerned solely with administered radioisotopes. Nevertheless, it is a useful and surprisingly stimulating document. It follows an earlier report (1972) from the same organizations on the same subject, and a number of other related reports, mostly dealing with the training of various radiation staff. The members of the committee were drawn from many countries (mostly "developed") in four continents and clearly encompass a wide range of experience. The first chapter deals with the development of nuclear medicine, its contribution to health and research and possible future trends. The next three chapters make specific recommendations about the provision and organization of nuclear medicine facilities, suggested staffing and equipment. Together they would prove useful to any hospital, region or country embarking on a nuclear medicine service or enlarging exist-
ing facilities. Individual planners may find the schedules of floor area, suggested staff and equipment valuable for banging on the doors of funding authorities. There is a very sensible emphasis on the reliability of equipment and provision for maintenance, with specific suggestions for the duplication of items and in some circumstances investment in spare parts. Thus far the report is competent, well-balanced, but predictable. Chapter 5 on the funding of nuclear medicine services paves the way for a most welcome and thoughtprovoking discussion of cost effectiveness in nuclear medicine. Techniques of evaluation of diagnostic procedures are described and examples given of their application in nuclear medicine. These ideas are further developed in four of the Annexes where useful lists of alternative non-nuclear procedures are included. No answers are given as to which procedures are most cost effective, but there is guidance on how the questions should be asked. These considerations are not unique to nuclear medicine, of course, and this section could be read with advantage by anyone concerned with diagnostic procedures who has not yet given attention to cost effectiveness. Investing in this report could be much more profitable than putting the money into a Swiss bank.
184
P. TOTHILL.
MARCH
1977
Bone thinning in frontal mucocele By A. R. Jackson, M.B., Ch.B., D.M.R.D., F.R.C.R. Wessex Neurological Centre, Southampton (Received August, 1976) ABSTRACT
Sixteen cases of frontal mucocele are reviewed. Bone thinning leading to destruction of the sinus floor was shown to be a feature. It usually affects the superomedial margin of the orbital roof first, due to pressure on the area where the sinus wall is thinnest. Demonstrable thinning of either anterior or posterior sinus walls—a cardinal sign of frontal mucocele, is best shown by means of underpenetrated lateral radiographs. All other conventional radiographic signs of frontal mucocele, including lucency of the affected sinus, were found to be non-specific. The presence of an osteoma in a site likely to obstruct the frontonasal duct is a valuable adjunct to diagnosis.
The radiographic lucency paradoxically shown in some frontal mucoceles is the result of a thinning of the walls of the sinus, which can be demonstrated by means of soft tissue lateral radiographs. Schworer et ah (1972) proved in experiments with models that the image cast by a fluid-filled cavity will be less dense if its walls are thin. An attempt is made in this paper to define the radiological profile of mucoceles of the frontal sinus and to outline differential diagnostic criteria in respect of other lesions. CASE MATERIAL AND FINDINGS
Sixteen cases of frontal mucocele from the Wessex Neurological Centre, Southampton and the Liverpool Ear, Nose and Throat Infirmary were studied. The commonest clinical presentation (13 out of 16
patients) was a painless and non-pulsating unilateral proptosis. In three patients the proptosis was severe enough to have produced double vision. Sinus pain was a prominent feature in only one patient (Case 15, Table I), and only two others complained of pain in the region of the eyes and forehead. In Case 6, a patient undergoing treatment for nasal polyp, the frontal mucocele was a chance finding. Standard radiographic views of the paranasal sinuses were available, including occipito-frontal, occipito-mental, and lateral projections. Several patients were also examined by tomography of the frontal sinuses. The radiological features are given in Table I. In the coronal views, the main finding was destruction of the supero-medial margin of the roof of the underlying orbit. Increased sinus opacity was present in nine patients, this appearance being consistent with a fluid-filled sinus. No fluid levels were seen. Of the remaining seven patients, three had hyperlucent frontal sinuses. Osteomata were seen in three patients, situated in sites considered likely to obstruct the frontonasal duct. Sclerosis of the bony margin of the affected sinus was present in five of the 16 patients. In lateral projections bone thinning was convincingly demonstrated in a total of nine patients; underpenetrated films showed it better.
TABLE I RADIOLOGICAL FEATURES OF 16 PATIENTS
181
Increased sinus density
Sclerotic margin + I+ I+ I I I I I+ I I+ I I
t
Osteoma
+ + I ++ I I + I ++ I ++ I I
Female, 58, Painless proptosis, diplopia Female, 53, Painless proptosis, diplopia Male, 79, Painless proptosis Male, 73, Painless proptosis Female, 60, Painless proptosis, diplopia Female, 36, Nasal polyp Female, 76, Painless proptosis Male, 75, Painless proptosis Female, 64, Painless proptosis Female, 56, Painless proptosis Male, 50, Pansinusitis Male, 56, Pain round eye, proptosis Male, 54, Painless proptosis Female, 46, Painless proptosis Male, 48, Pansinusitis Male, 46, Painless proptosis
+ I ++ I I + I I + + + I I + +
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Orbital erosion Bone thinning
I I I I I I I I I + I I + I I +
Cases
VOL.
50, No. 591 A. R. Jackson
FIG. 1. Right frontal mucocele-occipito-frontal and lateral projections. There is loss of the superior orbital" margin, the sinus is lucent. The lateral projection shows a sinus of small depth with a thinned anterior wall.
FIG. 2. Right frontal mucocele-occipito-frontal and lateral projections. Loss of the superior orbital margin, but a sinus of increased density. The lateral projection shows a sinus of increased depth.
182
MARCH 1977
Bone thinning in frontal mucocele TABLE II
present alone, or in the controls. The anteroposterior diameter of the control group varied widely, from 0.5 to 2.6 cm, averaging 1.2 cm. Bone thinning Bone thinning According to Gray (1973) the average diameter of with increased with lucent the frontal sinus is 1.8 cm. These measurements are opacity sinus Control group significantly lower than the average of the group 2.4 1.2 1.1 2.0 showing a combination of bone thinning and in2.7 1.4 2.3 0.9 creased opacity, namely 2.3 cm. The wide variation 2.2 1.6 0.7 0.9 in the control group confirms that it is impossible to 1.9 1.1 0.8 1.1 0.8 0.7 1.8 diagnose pathological antero-posterior expansion of 1.5 1.0 a sinus in any individual patient without the 0.8 0.9 benefit of serial radiographic examinations. 1.7 0.7 0.5 2.6 Loss of the normal sclerotic sinus margin is said 0.9 1.4 to be an early change in mucocele, which occurs prior to expansion of the sinus (Samuel, 1968), and the findings in nine patients confirm this. Loss of the The depth of the frontal sinus was measured in convoluted pattern of the affected sinus (Wolfowitz three groups (Table II): (1) cases of frontal mucocele and Solomon, 1972) and deviation of the intersinus exhibiting bone thinning and increased opacity of septum towards the unaffected side are also believed the sinus—four patients; (2) cases with frontal to be unreliable signs, unless confirmed by serial mucoceles exhibiting bone thinning and lucent or examinations. In life the frontal sinuses are usually hyper-lucent sinuses—five patients; and (3) a asymmetrical, and deviation of the intersinus septum randomly-selected control group—20 subjects. The is a common normal variant (Gray, 1973). findings (Table II) showed that a significantly Squamous carcinoma of the frontal sinus, a rare greater average sinus depth was present in the entity, may present the same pattern of destruction Group 1 patients than in the other groups. in coronal views as frontal mucocele (Boone and Harle, 1968), but the lateral projection is said usually to show early destruction of the walls, rather DISCUSSION Frontal mucocele accounts for 15% of the patients than the typical thinning exhibited by a mucocele. with unilateral exophthalmos presenting to an ear, Kriise and Neumann (1974), in a review of four cases nose and throat surgeon (Zizmor and Noyek, 1968) of sinus disease in which the diagnosis was in doubt, and 3% of those presenting to an ophthalmic surgeon claimed that surgical biopsy may be the only way of (Reese, 1963). Most authors (Wolfowitz and providing a definitive answer. Defects of cranial Solomon, 1972; Iliff, 1973) agree that pain is not a fusion such as meningocele and encephalocele of the feature of the condition. However, Bordley and frontal region in adults are said to mimic mucocele if Bosley (1973) found a high incidence of headache in the characteristic mid-line defect in the skull is not a series of cases which was notable for its high visible (Zizmor and Noyek, 1968). Plain-film changes, similar to a mucocele, were present in a complication rate. The characteristic radiological finding in this 23-year-old patient with an olfactory neuroblastoma series was destruction of the layer of bone separating who presented at the Wessex Neurological Centre the sinus from the orbit, which is the thinnest part with a short history of pain and proptosis. of the sinus wall (Cunningham, 1972). Consequently this is its weakest part and it will be affected first by ACKNOWLEDGMENTS an expanding lesion of the frontal sinus. I would like to thank Dr. E. H. Burrows for his helpful and criticism, and also Dr. R. W. Galloway for Thinning of the anterior and posterior sinus walls advice providing access to his cases at the Liverpool Ear, Nose and may be demonstrated in lateral projections—it was Throat Infirmary. present in nine of the 16 patients reviewed. If convincingly present, it represents a reliable sign of REFERENCES mucocele. BOONE, M. L. M., and HARLE, T. S., 1968. Malignant tumours of the paranasal sinuses. Seminars in RoentThe patients in whom a combination of bone genology, 3, 202-213. thinning and increased opacity was present, posses- BORDLEY, J. E., and BOSLEY, W. R., 1973. Mucoceles of the front sinus—causes and treatment. Annals of Otology, sed a greater average antero-posterior diameter of Rhinology and Laryngology, 82, 696—702. the frontal sinuses than was shown either in those CUNNINGHAM'S Textbook of Anatomy. 11 th ed. Edited by patients in whom one or other of these features was G. J. Romanes, London 1972 (Oxford University Press). DEPTH OF FRONTAL SINUS (CM)
183
VOL.
50, No. 591 A. R. Jackson
GRAY'S Anatomy. 35th ed. 1973 (Longman). Sinus depth 1.8p.1092. Deviation of septum - p.299. ILIFF, C , 1973. Mucoceles in the orbit. Archives of Ophthalmology, 89, 392-395.
paranasal sinuses. Seminars in Roentgenology, 3,148-159. SCHWORER I., GERSTENBERG, E., and KRAUSE, H. C , 1972.
Die Mukocele der Nasennebenhohle-ein Rontgendiagnotisches Problem? Fortschritte auf dem Gebiete der Rontgenstrohlen und der Nuklearmedizin, 117, 642-647.
KRUSE, C. G., and NEUMANN, O. G., 1974. Nasenneben-
hohlen-Mucocelen mit der Symptomatik Maligner WOLFOWITZ, B. L., and SOLOMON, A., 1972. Mucoceles of Tumoren. H.N.O. Wegweiser fur die Fagheerytliche the frontal and ethmoid sinuses. Journal of Laryngology Praxis, 22,195-197. and Otology, 86, 79-82. REESE, A. B. Tumours of the Eye. 2nd ed., 529-580. New ZIZMOR, J., and NOYEK, A. M., 1968. Cysts and benign York Hoeber Medical Division, Harper and Row. tumours of the paranasal sinuses. Seminars in Roentgenology, 3, 172-201. SAMUEL, E., 1968. Inflammatory diseases of the nose and
Book review Nuclear Medicine: Report of a joint I.A.E.A./W.H.O. expert committee on the use of ionizing radiation and radioisotopes for medical purposes (nuclear medicine). Technical Report Series 591, pp. 72, 1976 (World Health Organization, Geneva), Sw. Fr. 7. The title of this report is somewhat misleading, as it could be construed to include X-ray diagnosis and beam radiotherapy, whereas it is concerned solely with administered radioisotopes. Nevertheless, it is a useful and surprisingly stimulating document. It follows an earlier report (1972) from the same organizations on the same subject, and a number of other related reports, mostly dealing with the training of various radiation staff. The members of the committee were drawn from many countries (mostly "developed") in four continents and clearly encompass a wide range of experience. The first chapter deals with the development of nuclear medicine, its contribution to health and research and possible future trends. The next three chapters make specific recommendations about the provision and organization of nuclear medicine facilities, suggested staffing and equipment. Together they would prove useful to any hospital, region or country embarking on a nuclear medicine service or enlarging exist-
ing facilities. Individual planners may find the schedules of floor area, suggested staff and equipment valuable for banging on the doors of funding authorities. There is a very sensible emphasis on the reliability of equipment and provision for maintenance, with specific suggestions for the duplication of items and in some circumstances investment in spare parts. Thus far the report is competent, well-balanced, but predictable. Chapter 5 on the funding of nuclear medicine services paves the way for a most welcome and thoughtprovoking discussion of cost effectiveness in nuclear medicine. Techniques of evaluation of diagnostic procedures are described and examples given of their application in nuclear medicine. These ideas are further developed in four of the Annexes where useful lists of alternative non-nuclear procedures are included. No answers are given as to which procedures are most cost effective, but there is guidance on how the questions should be asked. These considerations are not unique to nuclear medicine, of course, and this section could be read with advantage by anyone concerned with diagnostic procedures who has not yet given attention to cost effectiveness. Investing in this report could be much more profitable than putting the money into a Swiss bank.
184
P. TOTHILL.
