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Lymphoepithelial cyst of the parotid gland
Britkh Journal of Oral and Maxiliofacial Surgery (1990) Z&329-332 0
1990 The British
Association
of Oral and Maxillofacial
Lymphoepithelial A. C. Camilleri,
Surgeons
1
02664356x/90/00284329/$10.00
cyst of the parotid gland
R. E. Lloyd
Department of Oral & Maxillofacial Surgery, Royal Surrey County Hospital, Surrey
SUMMARY. A case of a lymphoepithelial diagnosis and management are discussed, lymphoepithelial (branchial) cysts.
cyst presenting as a parotid tumour is described. Aspects of as well as current theories on the origin and development of
INTRODUCTION The first branchial cyst was described by Hunczowski in 1789. However, the first recorded treatment was by Langenbeck in 1859. Hildebrandt in 1895 described the first branchial cyst arising in the parotid gland. Cystic lesions in the parotid gland are uncommon and they are often misdiagnosed as benign tumours. The origin of branchial cysts has been a subject of controversy for many years and, because of this, the accuracy of the term branchial cyst h.as been questioned. The trend nowadays is to call such cysts ‘lymphoepithelial cysts’, which simply describes their histological appearance and takes no account of their origin and development. A case of a so-called branchial cyst arising in the parotid gland is described and points are raised regarding diagnosis and management of such lesions. Case report A 31-year-old male university student of Nigerian origin was referred to the Maxillofacial Department by his general medical practitioner. He complained of a 6 to 7 week history of a swelling at the left angle of his mandible. The swelling was painless and did not fluctuate in size. It had, however, increased slowly in size since first being noticed. The medical history was non-contributory. Clinical examination revealed a firm tender swelling approximately 3 cm in diameter, just posterior to the left angle of the mandible, beneath the left ear lobe. It was non-fluctuant. All cranial nerves were functioning normally. Intra-oral examination revealed no parapharyngeal swelling and clear saliva was expressed from the left parotid duct. Plain radiographs revealed no abnormality. Thus, a provisional diagnosis of a parotid tumour was reached and arrangements were made for CT sialography. The result of this investigation showed the swelling to be a large space occupying lesion within the superficial lobe of the parotid gland (Fig. 1). The lesion appeared to be a solid tumour closely opposed to the posterior belly of the diagastric muscle. The following day under general anaesthesia a left superficial parotidectomy was carried out to remove the
Fig. I- CT sialogram showing solid looking tumour within the superficial lbbe of the parotid gland (arrow). The normal glandular tissue is full of radio-opaque dye.
appeared to be penetrating the mass at its deep surface. The superficial lobe of the parotid gland was removed with the lesion contained within this clinically normal glandular tissue. During the dissection the tumour was found to be lying between the internal and external carotid arteries and consequently the external carotid artery was ligated to gain access. The operative site was closed in layers and vacuum drainage applied. The patient made a good postoperative recovery and was discharged home on the 7th postoperative day. The only complication was a slight facial nerve paresis. The patient was followed up regularly and was shown to regain full function of his facial nerve by the second postoperative month.
tumour. The branches of the left facial nerve were identified and preserved, apart from the cervical branch, as this 329
330
British
Journal
of Oral and Maxillofacial
Surgery
The histological report on the specimen submitted for examination showed the tumour to be a lymphoepithelial, or branchial, cyst arising within the parotid gland. The gland displayed mild non-specific sialadenitis (Fig. 2) adjacent to a cyst lined by poorly defined non-keratinising squamous epithelium. There was abundant lymphoid tissue within the cyst wall (Fig. 3). The lymphoid tissue within the cyst wall and that in other intraparotid lymph nodes displayed non-specific reactive follicular hyperplasia.
DISCUSSION 70 cases of parotid branchial cysts have been reported in the literature, the age range being between 16 to 69 years. The mean age is 44 years with a male:female ratio of 3:l. The majority of cases were unilateral with a greater number arising in the right parotid gland rather than the left gland. In this case, all the preoperative examinations and investigations indicated that the swelling was due to a parotid tumour-possibly a malignant tumour, as indicated by the short history. The fact that there was no apparent facial nerve involvement did not exclude a malignant tumour, as not all malignant parotid tumours invade perineurally. The CT scans showed what appeared to be a solid tumour lying within the parotid gland. However, Harnsberger et al. (1984) examined, using CT, a series of 38 patients in whom branchial cysts had been diagnosed clinically (both in the parotid and cervical region). They found that every lesion, which at operation turned out to be a branchial cyst, showed up as a fluid filled mass on preoperative CT scan. They also obtained false positives: where cystic lesions diagnosed as such on CT were in fact found to be other lesions at operation: haemangiomata and pleomorphic adenomata. Therefore, in this case the CT scan was misleading. Other investigations which might have been helpful in obtaining a preoperative diagnosis are: About
aspirate containing cholesterol crystals suggesting a cystic lesion. Aspirating under CT control allows the operator to be more accurate with the placement of the needle and thus avoids aspiration outside the lesion. The value of ultrasound as an aid to diagnosis of such lesions was documented by Badami and Athey (1981) and more recently by Earl and Ward-Booth (1985). Thus, in retrospect, further investigation of the lesion might have helped to obtain a more accurate preoperative diagnosis. In general it is important to try to obtain a preoperative diagnosis of any head and neck swelling, as this will affect patient handling and may affect management of the lesion itself. Knowing the exact nature of the lesion in this case however would not have changed the overall management. The origin and development of branchial cysts is a controversial subject, and many theories have been suggested. Unfortunately because of the complicated embryological development of this region none of the theories have been proven by embryological investigation. The theories simply attempt to collate known embryological fact with clinical findings. After the first recorded treatment in 1859, Langenbeck, on very little evidence, declared the lesion to be derived from branchial remnants. Similar cases were recorded subsequently, and eventually such lesions became a clinical entity, labelled as being of branchiogenic origin. The debate as to the origin of these cysts reached a climax in the 1920s and 1930s. However, to this day the controversy still exists and at least four theories have been put forward to explain the origins of the branchial cysts: 1 2 3 4
Branchial apparatus theory Cervical sinus theory Thymo-pharyngeal duct theory Inclusion theory.
Aspiration of the mass might have produced a fluid
Histologically, more than 90% of branchial cysts have abundant sub-epithelial lymphoid tissue in their wall, either in diffuse bands or in prominent follicular pattern with germinal centres (Maran & Buchanan,
Fig. 2 - Photomicrograph showing mild sialadenitis adjacent a poorly defined non-keratinising squamous epithelium wall (Stain - H&E. Original magnification x63.)
Fig. 3 - Photomicrograph showing lymphoid tissue in nonkeratinising squamous epithelial cyst wall. (Stain - H&E. Original magnification X 100.)
1 2
Fine needle aspiration Ultrasound.
to
Lymphoepithelial
1978). The origin of this lymphoid tissue is also a matter of discussion and it is not satisfactorily explained by all theories. Branchial apparatus theory
This theory was put forward by Von Acherson (1832), who suggested that the cysts aro’se from remnants of the pharyngeal pouches, branchial clefts or both. These remain dormant until an external stimulus causes proliferation and cyst formation. These epithelial remnants may later become surrounded by lymphoid tissue-giving rise to the classic histology.
cyst of the parotid
gland
331
arising within the parotid gland may be explained thus, as the parotid gland does not arise from the branchial apparatus. The Bhaskar and Bernier theory was contested by Little and Rickles (1967), who said it was incorrect to assume that the epithelium in lymphoepithelial cysts always derived from salivary tissue. They felt that the position of the cyst may give a clue as to the source of the epitheliumbranchial or salivary. After a review of the literature, Stewart et al. (1974) could not conceive how a cyst developing in the parotid gland could migrate to the distant positions sometimes occupied, thus disagreeing with the inclusion theory.
The cervical sinus theory
This theory is an extension of the first theory. When the 2nd branchial arch grows caudally to meet the 5th arch, the imprisoned ectoderm may give rise to a cyst. However, if branchial cysts do arise from the branchial apparatus then one would expect a high proportion to be present at birth, or at least soon after. The peak age incidence of branchial cysts is the 3rd and 4th decades, with only one reported case at birth (Karlan et al., 1965). In cysts of undisputed congenital origin, such as thyroglossal cysts, the peak age incidence is 5 years of age (Ward, 1970). Thymo-pharyngeal
duct theory
This was proposed by Wenglowski in 1913 and later supported by Meyer (1932) and McNealy (1942). It was suggested that the cyst formed from a remnant of the connection between the thymus and the 3rd pouch from which it derives. However, a persistent thymic duct has never been described. Also, no branchial cyst has ever been reported deep to the thyroid gland, which is the position it would have to reach if this theory were correct. Apart from this, thymic and thyroid tissue has never been seen in branchial cyst walls, though thymic tissue may resemble lymphoid tissue histologically. Inclusion theory
King, in 1949, suggested that the cysts arose from sequestered lymph node epithelium. He also proposed that the cysts be called ‘lateral cysts of the neck’. Bhaskar and Bernier (1959) proposed that the epithelium within the lymph node derived from glandular parotid tissue. The parotid gland, in the foetus, arises in close proximity to parotid and cervical lymph nodes. The developing parotid gland has no capsule to hinder mingling of lymphoid and glandular tissue. Following this proposal, Bhaskar and Bernier (1959) suggested the name ‘lymphoepithelial cyst’ for these entities. This theory may satisfactorily explain the frequent finding of lymphoid tissue in the cyst walls. Also, the origin of cysts
Conclusion
There is still no agreement on the exact origins of these cysts. It may be that the lesions termed branchial cysts are not genetically or developmentally homogenous. A review of the literature suggests cystic degeneration within lymph nodes, with epithelium from different sources trapped inside. In view of their histological homogeneity, however, it would seem reasonable to group these lesions under the heading of ‘lymphoepithelial’ cysts, irrespective of their exact origin. In the case of lymphoepithelial cysts arising within the parotid gland, the inclusion theory would seem the most feasible explanation.
References Badami, J. P. & Athey, P. A. (1981). Sonography in the diagnosis of branchial cysts. American Journal of Roentgenology, 157, 1245. Bhaskar, S. W. & Bernier, J. L. (1959). Histogenesis of branchial cysts: a report of 461 cases. American Journal of Pathology, 35, 407. Earl, P. D. & Ward-Booth, R. P. (1985). A case of branchial l(lympho-epithelial) cyst, illustrating the value of ultrasound in diagnosis of cervical swellings. British Journal of Oral & Maxillofacial Surgery, 23,292. Harnsberger, H., Mancuso, A., Muraki, A. S., Byrd, S. E., Dillon, W. P., Johnson, L. P. & Hanafee, W. N. (1984). Branchial cleft anomalies and their mimics: computed tomographic evaluation. Radiology, 152, 739. Hildcbrandt, 0. (1895). Uber angeborene epitheliale cysten und fisteln des halses. Archiv fur Klinische Chirurgie, 49, 167. Hunczowski, J. N. (1789). Quoted by D. P. McGuire, (1935). Branchiogenetic or branchial fistulae. American Medicine, 41,324. Karlan, M. S., Michel, S. L. & Snyder, W. H. (1965). Branchiogenic cysts; congenital or acquired. American Journal of Surgery, 110,615. King, E. S. J. (1949). The lateral lympho-epithelial cyst of the neck (branchial cyst). Australian and New Zealand Journal of Surgery, 19, 109. Langenbeck, B. (1859). Exsterpation einer Dermoidcyste von der Scheide der grossen Halsgefasse. Verwundung der Vena jugularis communis. Stillung der blutung durch Compression Heilung. Archiv fur Klinische Chirurgie, 1,25. j Little, J. W. & Rickles, N. H. (1967). The histogenesis of the branchial cyst. American Journal of Pathology, 50, 533.
332 British Journal of Oral and Maxillofacial Surgery Maran. A. G. D. & Buchanan, D. R. (1978). Branchial cysts, sinuses and fistulae. Clinic& Otolaiyngdlogy, 3, 77. McNealy, R. W. (1942). Cystic tumors of the neck; thyroglossal and branchial cysts. Journal of the American Dental Association, 29, 1808.
Meyer, H. W. (1932). Congenital cysts and fistulae of the neck. Annals of Surgery, 95, 1. Stewart, S., Levy, R., Karpel, J. & Stoopack, J. (1974). Lymphoepithelial (branchial) cysts of the parotid gland. Journal of Oral Surgery, 32, 100. Von Acherson, F. M. (1832). De fistulis colli congenitis adjecta fissurarum branchialium in mammalibus avibusque historia succincta. Bertolini, Apud C. H. Jonas. Ward, P. H. (1970). The many faces of the thyroglossal duct. Transactions of the American Academy of Ophthalmology and Otolaryngology, 74,310. Wenglowski, R. (1913). Uber die Halsfisteln und Cysten. Archiv fur Klinische Chirurgie, 100, 789.
The Authors Andrew C. Camilleri BDS, FDSRCS
Registrar in Oral Surgery Richard E. L. Lloyd FDS, FRCS Senior Registrar in Oral Surgery Department of Oral and Maxillofacial Surgery Royal Surrey County Hospital Egerton Road Guildford Surrey GU2 5xX Correspondence Camilleri
and requests for offprints to Mr Andrew C.
Paper received 18 January 1990 Accepted 11 February 1990
1990 The British
Association
of Oral and Maxillofacial
Lymphoepithelial A. C. Camilleri,
Surgeons
1
02664356x/90/00284329/$10.00
cyst of the parotid gland
R. E. Lloyd
Department of Oral & Maxillofacial Surgery, Royal Surrey County Hospital, Surrey
SUMMARY. A case of a lymphoepithelial diagnosis and management are discussed, lymphoepithelial (branchial) cysts.
cyst presenting as a parotid tumour is described. Aspects of as well as current theories on the origin and development of
INTRODUCTION The first branchial cyst was described by Hunczowski in 1789. However, the first recorded treatment was by Langenbeck in 1859. Hildebrandt in 1895 described the first branchial cyst arising in the parotid gland. Cystic lesions in the parotid gland are uncommon and they are often misdiagnosed as benign tumours. The origin of branchial cysts has been a subject of controversy for many years and, because of this, the accuracy of the term branchial cyst h.as been questioned. The trend nowadays is to call such cysts ‘lymphoepithelial cysts’, which simply describes their histological appearance and takes no account of their origin and development. A case of a so-called branchial cyst arising in the parotid gland is described and points are raised regarding diagnosis and management of such lesions. Case report A 31-year-old male university student of Nigerian origin was referred to the Maxillofacial Department by his general medical practitioner. He complained of a 6 to 7 week history of a swelling at the left angle of his mandible. The swelling was painless and did not fluctuate in size. It had, however, increased slowly in size since first being noticed. The medical history was non-contributory. Clinical examination revealed a firm tender swelling approximately 3 cm in diameter, just posterior to the left angle of the mandible, beneath the left ear lobe. It was non-fluctuant. All cranial nerves were functioning normally. Intra-oral examination revealed no parapharyngeal swelling and clear saliva was expressed from the left parotid duct. Plain radiographs revealed no abnormality. Thus, a provisional diagnosis of a parotid tumour was reached and arrangements were made for CT sialography. The result of this investigation showed the swelling to be a large space occupying lesion within the superficial lobe of the parotid gland (Fig. 1). The lesion appeared to be a solid tumour closely opposed to the posterior belly of the diagastric muscle. The following day under general anaesthesia a left superficial parotidectomy was carried out to remove the
Fig. I- CT sialogram showing solid looking tumour within the superficial lbbe of the parotid gland (arrow). The normal glandular tissue is full of radio-opaque dye.
appeared to be penetrating the mass at its deep surface. The superficial lobe of the parotid gland was removed with the lesion contained within this clinically normal glandular tissue. During the dissection the tumour was found to be lying between the internal and external carotid arteries and consequently the external carotid artery was ligated to gain access. The operative site was closed in layers and vacuum drainage applied. The patient made a good postoperative recovery and was discharged home on the 7th postoperative day. The only complication was a slight facial nerve paresis. The patient was followed up regularly and was shown to regain full function of his facial nerve by the second postoperative month.
tumour. The branches of the left facial nerve were identified and preserved, apart from the cervical branch, as this 329
330
British
Journal
of Oral and Maxillofacial
Surgery
The histological report on the specimen submitted for examination showed the tumour to be a lymphoepithelial, or branchial, cyst arising within the parotid gland. The gland displayed mild non-specific sialadenitis (Fig. 2) adjacent to a cyst lined by poorly defined non-keratinising squamous epithelium. There was abundant lymphoid tissue within the cyst wall (Fig. 3). The lymphoid tissue within the cyst wall and that in other intraparotid lymph nodes displayed non-specific reactive follicular hyperplasia.
DISCUSSION 70 cases of parotid branchial cysts have been reported in the literature, the age range being between 16 to 69 years. The mean age is 44 years with a male:female ratio of 3:l. The majority of cases were unilateral with a greater number arising in the right parotid gland rather than the left gland. In this case, all the preoperative examinations and investigations indicated that the swelling was due to a parotid tumour-possibly a malignant tumour, as indicated by the short history. The fact that there was no apparent facial nerve involvement did not exclude a malignant tumour, as not all malignant parotid tumours invade perineurally. The CT scans showed what appeared to be a solid tumour lying within the parotid gland. However, Harnsberger et al. (1984) examined, using CT, a series of 38 patients in whom branchial cysts had been diagnosed clinically (both in the parotid and cervical region). They found that every lesion, which at operation turned out to be a branchial cyst, showed up as a fluid filled mass on preoperative CT scan. They also obtained false positives: where cystic lesions diagnosed as such on CT were in fact found to be other lesions at operation: haemangiomata and pleomorphic adenomata. Therefore, in this case the CT scan was misleading. Other investigations which might have been helpful in obtaining a preoperative diagnosis are: About
aspirate containing cholesterol crystals suggesting a cystic lesion. Aspirating under CT control allows the operator to be more accurate with the placement of the needle and thus avoids aspiration outside the lesion. The value of ultrasound as an aid to diagnosis of such lesions was documented by Badami and Athey (1981) and more recently by Earl and Ward-Booth (1985). Thus, in retrospect, further investigation of the lesion might have helped to obtain a more accurate preoperative diagnosis. In general it is important to try to obtain a preoperative diagnosis of any head and neck swelling, as this will affect patient handling and may affect management of the lesion itself. Knowing the exact nature of the lesion in this case however would not have changed the overall management. The origin and development of branchial cysts is a controversial subject, and many theories have been suggested. Unfortunately because of the complicated embryological development of this region none of the theories have been proven by embryological investigation. The theories simply attempt to collate known embryological fact with clinical findings. After the first recorded treatment in 1859, Langenbeck, on very little evidence, declared the lesion to be derived from branchial remnants. Similar cases were recorded subsequently, and eventually such lesions became a clinical entity, labelled as being of branchiogenic origin. The debate as to the origin of these cysts reached a climax in the 1920s and 1930s. However, to this day the controversy still exists and at least four theories have been put forward to explain the origins of the branchial cysts: 1 2 3 4
Branchial apparatus theory Cervical sinus theory Thymo-pharyngeal duct theory Inclusion theory.
Aspiration of the mass might have produced a fluid
Histologically, more than 90% of branchial cysts have abundant sub-epithelial lymphoid tissue in their wall, either in diffuse bands or in prominent follicular pattern with germinal centres (Maran & Buchanan,
Fig. 2 - Photomicrograph showing mild sialadenitis adjacent a poorly defined non-keratinising squamous epithelium wall (Stain - H&E. Original magnification x63.)
Fig. 3 - Photomicrograph showing lymphoid tissue in nonkeratinising squamous epithelial cyst wall. (Stain - H&E. Original magnification X 100.)
1 2
Fine needle aspiration Ultrasound.
to
Lymphoepithelial
1978). The origin of this lymphoid tissue is also a matter of discussion and it is not satisfactorily explained by all theories. Branchial apparatus theory
This theory was put forward by Von Acherson (1832), who suggested that the cysts aro’se from remnants of the pharyngeal pouches, branchial clefts or both. These remain dormant until an external stimulus causes proliferation and cyst formation. These epithelial remnants may later become surrounded by lymphoid tissue-giving rise to the classic histology.
cyst of the parotid
gland
331
arising within the parotid gland may be explained thus, as the parotid gland does not arise from the branchial apparatus. The Bhaskar and Bernier theory was contested by Little and Rickles (1967), who said it was incorrect to assume that the epithelium in lymphoepithelial cysts always derived from salivary tissue. They felt that the position of the cyst may give a clue as to the source of the epitheliumbranchial or salivary. After a review of the literature, Stewart et al. (1974) could not conceive how a cyst developing in the parotid gland could migrate to the distant positions sometimes occupied, thus disagreeing with the inclusion theory.
The cervical sinus theory
This theory is an extension of the first theory. When the 2nd branchial arch grows caudally to meet the 5th arch, the imprisoned ectoderm may give rise to a cyst. However, if branchial cysts do arise from the branchial apparatus then one would expect a high proportion to be present at birth, or at least soon after. The peak age incidence of branchial cysts is the 3rd and 4th decades, with only one reported case at birth (Karlan et al., 1965). In cysts of undisputed congenital origin, such as thyroglossal cysts, the peak age incidence is 5 years of age (Ward, 1970). Thymo-pharyngeal
duct theory
This was proposed by Wenglowski in 1913 and later supported by Meyer (1932) and McNealy (1942). It was suggested that the cyst formed from a remnant of the connection between the thymus and the 3rd pouch from which it derives. However, a persistent thymic duct has never been described. Also, no branchial cyst has ever been reported deep to the thyroid gland, which is the position it would have to reach if this theory were correct. Apart from this, thymic and thyroid tissue has never been seen in branchial cyst walls, though thymic tissue may resemble lymphoid tissue histologically. Inclusion theory
King, in 1949, suggested that the cysts arose from sequestered lymph node epithelium. He also proposed that the cysts be called ‘lateral cysts of the neck’. Bhaskar and Bernier (1959) proposed that the epithelium within the lymph node derived from glandular parotid tissue. The parotid gland, in the foetus, arises in close proximity to parotid and cervical lymph nodes. The developing parotid gland has no capsule to hinder mingling of lymphoid and glandular tissue. Following this proposal, Bhaskar and Bernier (1959) suggested the name ‘lymphoepithelial cyst’ for these entities. This theory may satisfactorily explain the frequent finding of lymphoid tissue in the cyst walls. Also, the origin of cysts
Conclusion
There is still no agreement on the exact origins of these cysts. It may be that the lesions termed branchial cysts are not genetically or developmentally homogenous. A review of the literature suggests cystic degeneration within lymph nodes, with epithelium from different sources trapped inside. In view of their histological homogeneity, however, it would seem reasonable to group these lesions under the heading of ‘lymphoepithelial’ cysts, irrespective of their exact origin. In the case of lymphoepithelial cysts arising within the parotid gland, the inclusion theory would seem the most feasible explanation.
References Badami, J. P. & Athey, P. A. (1981). Sonography in the diagnosis of branchial cysts. American Journal of Roentgenology, 157, 1245. Bhaskar, S. W. & Bernier, J. L. (1959). Histogenesis of branchial cysts: a report of 461 cases. American Journal of Pathology, 35, 407. Earl, P. D. & Ward-Booth, R. P. (1985). A case of branchial l(lympho-epithelial) cyst, illustrating the value of ultrasound in diagnosis of cervical swellings. British Journal of Oral & Maxillofacial Surgery, 23,292. Harnsberger, H., Mancuso, A., Muraki, A. S., Byrd, S. E., Dillon, W. P., Johnson, L. P. & Hanafee, W. N. (1984). Branchial cleft anomalies and their mimics: computed tomographic evaluation. Radiology, 152, 739. Hildcbrandt, 0. (1895). Uber angeborene epitheliale cysten und fisteln des halses. Archiv fur Klinische Chirurgie, 49, 167. Hunczowski, J. N. (1789). Quoted by D. P. McGuire, (1935). Branchiogenetic or branchial fistulae. American Medicine, 41,324. Karlan, M. S., Michel, S. L. & Snyder, W. H. (1965). Branchiogenic cysts; congenital or acquired. American Journal of Surgery, 110,615. King, E. S. J. (1949). The lateral lympho-epithelial cyst of the neck (branchial cyst). Australian and New Zealand Journal of Surgery, 19, 109. Langenbeck, B. (1859). Exsterpation einer Dermoidcyste von der Scheide der grossen Halsgefasse. Verwundung der Vena jugularis communis. Stillung der blutung durch Compression Heilung. Archiv fur Klinische Chirurgie, 1,25. j Little, J. W. & Rickles, N. H. (1967). The histogenesis of the branchial cyst. American Journal of Pathology, 50, 533.
332 British Journal of Oral and Maxillofacial Surgery Maran. A. G. D. & Buchanan, D. R. (1978). Branchial cysts, sinuses and fistulae. Clinic& Otolaiyngdlogy, 3, 77. McNealy, R. W. (1942). Cystic tumors of the neck; thyroglossal and branchial cysts. Journal of the American Dental Association, 29, 1808.
Meyer, H. W. (1932). Congenital cysts and fistulae of the neck. Annals of Surgery, 95, 1. Stewart, S., Levy, R., Karpel, J. & Stoopack, J. (1974). Lymphoepithelial (branchial) cysts of the parotid gland. Journal of Oral Surgery, 32, 100. Von Acherson, F. M. (1832). De fistulis colli congenitis adjecta fissurarum branchialium in mammalibus avibusque historia succincta. Bertolini, Apud C. H. Jonas. Ward, P. H. (1970). The many faces of the thyroglossal duct. Transactions of the American Academy of Ophthalmology and Otolaryngology, 74,310. Wenglowski, R. (1913). Uber die Halsfisteln und Cysten. Archiv fur Klinische Chirurgie, 100, 789.
The Authors Andrew C. Camilleri BDS, FDSRCS
Registrar in Oral Surgery Richard E. L. Lloyd FDS, FRCS Senior Registrar in Oral Surgery Department of Oral and Maxillofacial Surgery Royal Surrey County Hospital Egerton Road Guildford Surrey GU2 5xX Correspondence Camilleri
and requests for offprints to Mr Andrew C.
Paper received 18 January 1990 Accepted 11 February 1990