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CASE REPORT
Intranasal epidermoid cyst causing upper airway obstruction in three brachycephalic dogs D. Murgia, M. Pivetta, K. Bowlt, C. Volmer, A. Holloway and R. Dennis Animal Health Trust, Centre for Small Animal Studies, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
This case report describes three brachycephalic dogs with intranasal epidermoid cysts that were causing additional upper airway obstruction. Although epidermoid cysts have been described in several locations in dogs, to the authors’ knowledge intranasal epidermoid cysts have not been previously reported. All dogs had mucopurulent to haemorrhagic nasal discharge. Magnetic resonance imaging of the head revealed the presence of unilateral or bilateral intranasal cystic lesions obstructing the nasal cavities partially or completely, with atrophy of the ipsilateral nasal turbinates. The cystic lesions were surgically excised in all dogs using a modified lateral alveolar mucosal approach to the affected nasal cavity. Aerobic, anaerobic and fungal culture of the cystic contents were negative and histology of the excised tissue was consistent with a benign intranasal epidermoid cyst in each dog. Upper airway obstruction was clinically improved in two dogs. Journal of Small Animal Practice (2014) 55, 431–435 DOI: 10.1111/jsap.12215 Accepted: 27 February 2014; Published online: 3 April 2014
additional upper airway obstruction and contributing to the BAOS exhibited by each.
INTRODUCTION The typical anatomical abnormalities leading to respiratory distress in brachycephalic breeds include stenotic nares, elongated and hyperplastic soft palate, narrowed rima glottidis, tracheal hypoplasia and laryngeal collapse (Koch et al. 2003). Recent studies have demostrated that additional constrictions in the upper airway including severe intranasal deformities such as hyperplastic turbinates contribute to brachycephalic airway obstructive syndrome (BAOS) (Oechtering et al. 2007). Excessive selection for extremes of conformation has led to deformity of the entire upper respiratory tract leading to stenosis of the nasal vestibule caused by the inner part of the nasal wing, nasal and nasopharyngeal obstruction due to hyperplastic and dysplastic conchae, nasopharyngeal collapse and laryngomalacia (Oechtering et al. 2007). It has been reported that shortening of the craniofacial skull and thus of the nasal cavity leads to rostral aberrant conchae (RAC) resulting in obstruction of the nasal passage and to caudal aberrant conchae (CAC) resulting in obstruction of the nasopharyngeal meatus (Oechtering et al. 2007, Oechtering 2010). These severe intranasal deformities in brachycephalic dogs are the basis for new pathophysiological understanding of BAOS. This case report serves to describe three brachycephalic dogs with intranasal epidermoid cysts that were causing Journal of Small Animal Practice
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Vol 55
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August 2014
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CASE HISTORIES A four-year-old entire male English bulldog (dog 1) was referred to the Centre for Small Animal Studies of the Animal Health Trust for assessment of a 5-month history of right unilateral nasal discharge and mild epistaxis. Coughing, lethargy and occasional pyrexia had been poorly responsive to antibacterial therapy. Previous aerobic, anaerobic and fungal culture of nasal discharge yielded Pseudomonas eaeruginosa. Upon presentation, all cardinal signs were within reference intervals. Right muco-purulent nasal discharge and brachycephalic syndrome-related respiratory signs were noted. Furthermore, absence of airflow through the right nasal passage was observed. Rhinoscopy revealed right nasal meatus occlusion by a multilobulated mass. A magnetic resonance imaging (MRI) scan of the head was then performed and an oval cystic mass lesion 36 mm (length, L) × 21 mm (height, H) × 26 mm (width, W) occupying the ventral two-thirds of the right nasal cavity between the root of the right maxillary canine and the ethmoturbinates was observed. The cyst contents were homogeneously hypointense in T1 weighted (T1W) images, hyperintense in T2-W (T2W) images (Fig 1a to c) and with a 3 to 4 mm thick, hypointense wall which enhanced moderately post
© 2014 British Small Animal Veterinary Association
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D. Murgia et al.
(a)
(b)
(c)
FIG 1. (a to c) Four-year-old male English bulldog (dog 1). (a) Sagittal T2-W, (b) dorsal T2-W and (c) transverse T2-W images of the head showing an oval cystic lesion (black arrow) filling the right nasal chamber extending from the right maxillary canine tooth to the ethmoturbinates. The cyst contents are homogeneously hyperintense. The osseous boundary of the nasopharyngeal meatus and the maxillary recess are destroyed (c). The cyst occludes the right nasopharyngeal meatus with consequent complete filling of the right frontal sinus (black asterisk), of the right maxillary recess and nasal turbinate interspace (black arrow head) with hyperintense secretions (a and c). The left intact maxillary recess is identified with a white asterisk (c)
contrast. The cyst obstructed the right nasopharyngeal meatus, with consequent complete filling of the right frontal sinus and nasal turbinate interspace with hyperintense secretions. A three-year-old entire male pug (dog 2) was referred to the Centre for Small Animal Studies of the Animal Health Trust for progressively increasing upper respiratory noises consistent with BAOS. Upon presentation, stenotic nares and bilateral nasal serous discharge associated with open mouth breathing were observed. At rhinoscopy left nasal chamber occlusion could be visualised. An MRI scan of the head revealed complete occlusion of the left nasal cavity for much of its length by a cystic structure 23 mm (L) × 9 mm (H) × 18 mm (W). Rostrally it surrounded the root of the left maxillary canine and caudally it extended into the common nasal meatus. Laterally, the maxillary recess appeared to be included in the cyst and the nasal septum was intact. A three-year-old neutered male pug (dog 3) was presented as an urgent referral with a 2-year history of upper respiratory dysfunction and episodes of apparent collapse over the preceding 432
48 hours. The dog had been diagnosed with a hiatal hernia and BAOS and had undergone a folding flap palatoplasty, alaplasty and everted laryngeal saccule removal 1 year before presentation. Over the few months before referral, deterioration of the brachycephalic syndrome related signs and purulent nasal discharge were reported. On the basis of physical examination and history, syncope secondary to upper airway obstruction was the initial suspect diagnosis. Rhinoscopy showed only occlusion of the right nasal chamber. An MRI scan of the head revealed a thin-walled, cystic structure 18 (L) × 12 (H) × 14 (W), filling the right nasal chamber and obstructing the choanae. The cyst, appeared to arise and to surround the caudal aspect of the right maxillary canine and first premolar tooth roots. The nasal turbinates on this side could not be recognised. Assessment of the upper airways under general anaesthesia revealed breed-associated elongation of the soft palate, bilateral laryngocoele and stenotic nares in dog 1, therefore staphylectomy, removal of the everted saccules and punch resection alaplasty was performed (Rostel 2010). Dog 2 also demonstrated
Journal of Small Animal Practice
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Vol 55
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August 2014
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© 2014 British Small Animal Veterinary Association
Intranasal epidermoid cyst in brachycephalic dogs
an elongated soft palate and tonsillar enlargement which were surgically corrected by staphylectomy and bilateral tonsillectomy. Surgical exploration using an alveolar mucosal approach to the affected nasal cavities was performed in all dogs (Priddy et al. 2001). A pharyngeal pack was placed to prevent inadvertent aspiration of blood or flushing fluids and dogs were positioned in lateral recumbency. A modification of the described technique was necessary to gain access to the lateral nasal chambers. Dog 1 underwent right lateral rhinotomy, dog 2 bilateral rhinotomy and dog 3 a left lateral rhinotomy. The lateral aspect of the maxillary bone was palpated and using a number 11 scalpel blade an incision was made through the maxillary gingival border from the caudal aspect of the canine to the fourth pre-molar tooth. Using a Freer periosteal elevator, in dogs 1 and 2 (left rhinotomy), the mucosa was elevated from the bone allowing the visualisation of a discoloured area associated with osteoatrophy of the maxilla delineating the lateral nasal cavity (Fig 2). Underneath,
FIG 2. Four-year-old male English bulldog (dog 1). Lateral alveolar mucosal approach to the right nasal cavity. Dorsal gingival mucosa elevation reveals discoloured and atrophic maxillary bone
FIG 3. Four-year-old male English bulldog (dog 1). Lateral alveolar mucosal approach to the right nasal cavity. Underneath the maxillary bone, following enlargement of the bony defect the opened cyst wall is visible Journal of Small Animal Practice
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the cyst was visible and was opened by the use of an artery forceps (Fig 3). During right lateral rhinotomy in dogs 2 and 3 maxillary bone atrophy was not encountered and a 1-mm intramedullary pin was used to create a hole into the nasal passage just caudal to the root of the maxillary canine. A series of increasing diameter pins and Smith Kerrison forceps were then used to enlarge the initial hole. The entire wall of the cyst was excised using a curette (Fig 4) and submitted for aerobic/anaerobic culture and histopathology (Fig 5). After complete excision of the cysts the interior of the rostral nasal cavities could be visualised. These were tested for patency by passing a fine silicone feeding tube into the nasopharynx and were flushed with sterile saline before closure. The rhinotomy was closed by apposing the alveolar mucosa with 4-0 Poliglecaprone 25 (Monocryl suture; Ethicon) in a simple interrupted pattern. Culture of the cystic fluid did not yield bacteria and results of histopathological evaluation of the removed tissue were consistent with an epidermoid cyst based on the classification published by Featherstone & Llabres Diaz (2003).
FIG 4. Three-year-old male pug (dog 3). Lateral alveolar mucosal approach to the right nasal cavity. Excision of the cyst wall
FIG 5. Three-year-old male pug (dog 3). Completely removed cyst
© 2014 British Small Animal Veterinary Association
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(b)
FIG 6. (a) Three-year-old male pug (dog 3). Histology of the cyst at low magnification. Area showing the pseudostratified columnar ciliated and mucous nasal epithelium (black arrow). Below this the stroma with inflammatory cell infiltration (black arrow-head) and the epidermoid cyst wall with the stratified squamous epithelium and discrete keratinisation (white arrow). The white arrow-head identifies some bone trabeculae (H&E. ×1). (b) Three-year-old male pug (dog 3). Histology of the cyst on high magnification. The cyst wall consists of a slightly keratinised stratified squamous epithelium and lies on a fibrous inflammatory stroma. The black arrow-head identifies the thin parakeratotic layers whereas the white-arrow head shows the spinous layers (H&E. ×20)
In all cases, a benign cystic structure within the nasal mucosa was found. The wall of this cyst consisted of a regular stratified squamous epithelium composed of a basal cuboidal layer, spinous layers and thin parakeratotic layers (Figs 6a, b). Epithelial cells were well differentiated. The lumen of the cysts contained sloughed epithelial cells, red blood cells and variable numbers of neutrophils and macrophages. The surrounding stroma was fibrous and infiltrated by variable numbers of inflammatory cells (lymphocytes, plasma cells and neutrophils). Dogs 1 and 3 recovered uneventfully from general anaesthesia and surgery and showed immediate relieve of upper respiratory obstruction signs. Dog 2 developed cardiorespiratory arrest following regurgitation and aspiration pneumonia during anaesthesia and died.
DISCUSSION This case series describes the diagnosis and surgical treatment of intranasal epidermoid cysts in three brachycephalic dogs that may have caused exacerbation of pre-existing signs of upper airway obstruction. In dogs epidermoid cysts have previously been reported in multiple locations which include the medial canthus of the eye (Davidson & Blanchard 1991), intracranially (Gormley et al. 1994, Platt et al. 1999, MacKillop et al. 2006, Steinberg et al. 2007, De Decker et al. 2012), the spinal cord and canal (Tomlinson et al. 1988, Shamir et al. 1999, Cappello et al. 2006, Lipitz et al. 2011) and in the nasopharynx (Ellison et al. 1995). To the authors’ knowledge, there have been no published reports of intranasal epidermoid cysts in the dog. Rhinoscopy identified different degrees of nasal chamber occlusion but did not add information regarding the nature of the obstruction, whereas the MRI scans permitted the identification of abnormal cystic structures associated with a partial or complete occlusion of the nasal passage. The differential diagnosis for cystic structures in this area included pure inflammatory lesions such as maxillary bone 434
epithelial cysts, dermoid cysts, dentigerous cysts, radicular cysts and canine odontogenic parakeratinised cysts (COPCs). These can be distinguished from one another by comparing the nature of the cellular component and the cyst content. Epithelial cysts have a simple non-stratified epithelial lininig and usually contain fluid of low cellularity (Featherstone & Llabres Diaz 2003). However, epidermoid cyst are a type of epithelial cyst that has a stratified, keratinised squamous epithelium and contains intraluminal breakdown products of desquamated epithelial cells (Davidson & Blanchard 1991, Featherstone & Llabres Diaz 2003). Epidermoid cysts can result from congenital sequestration of epithelial tissue, trauma or a foreign body reaction and are typically associated with a predominant inflammatory component that is absent in simple epithelial cysts (Davidson & Blanchard 1991). Finally, dermoid cysts are also lined by a stratified squamous epithelium but generally contain dermal appendages such as hair and sebaceous glands (Gormley et al. 1994). Dentigerous, radicular cysts and COPCs are subtypes of odontogenic cysts. Verstraete (2011) reported that over 50% of dogs presenting with odontogenic cysts were brachycephalic. The reason for the apparent high frequency of odontogenic cysts in these breeds is unknown, although crowding of the teeth as a result of cephalic conformation may be an underlying factor (Verstraete et al. 2011). Histopathological examination of dentigerous and radicular cysts in dogs shows the presence of a cyst lining of non-keratinised stratified squamous epithelium (Watanabe et al. 2004). By contrast, COPC histopathological features are consistent with stratified squamous epithelium of uniform thickness showing some parakeratinisation (Verstraete et al. 2011). Invasive dentigerous and radicular cysts typically surround respectively the crown of an unerupted tooth and the apex of a non-vital tooth. While COPCs, mainly identified in the maxilla, surround the roots of fully erupted, normally developed teeth and are characterised by locally infiltrative growth as seen in the present cases (Verstraete et al. 2011). On the basis of the classification of the general features of cystic structures reported by Featherstone & Llabres Diaz (2003), the
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histopathological findings of the three reported intranasal cysts were consistent with epidermoid cysts. Like epidermoid cysts, the lesions described here were space-occupying, slowly expanding, painless and fluid-filled cysts. However, they surrounded healthy maxillary tooth roots as COPCs are described to do (Verstraete et al. 2011). Their origin and aetiopathogenesis is therefore still unclear as the described epidermoid cysts and COPCs are similar in localisation, behaviour and histology. If not surgically removed they may become larger and cause pressure damage to the local surrounding tissues; neighbouring teeth may become displaced and maxillary/mandibular bone may become weakened and prone to fractures (Baxter 2004). Excision of the entire cyst wall and curettage is therefore essential (Baxter 2004). The intranasal cysts described in the brachycephalic dogs in this report strongly suggest that MRI or computed tomography (CT) of the upper respiratory airways should be considered as part of the diagnostic work-up in selected brachycephalic dogs. This would allow abnormalities which are part of a more complex form of upper airway obstructive syndrome to be detected and would permit better surgical planning. Surgery was performed to remove the cysts, restore nasal patency and relieve the upper airway obstruction, allowing better air flow. The lateral alveolar mucosal surgical approach to the affected nasal cavities was less invasive than a dorsal or ventral rhinotomy. It was felt that surgical approach via interventional rhinoscopy would not have provided adequate exposure of the cysts. The intranasal epidermoid cysts described in this report should be included as a differential diagnosis when assessing brachycephalic breeds presenting with clinical signs associated with BAOS and should be considered as contributing factor in the complex pathogenesis of the syndrome. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper.
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References Baxter, C. J. K. (2004) Bilateral mandibular dentigerous cysts in a dog. Journal of Small Animal Practice 45, 210-212 Cappello, R., Lamb, C. R. & Rest, J. R. (2006) Vertebral epidermoid cyst causing hemiparesis in a dog. Veterinary Record 158(25), 865-857 Davidson, H. J. & Blanchard, G. L. (1991) Periorbital epidermoid cyst in the medial canthus of three dogs. Journal of the American Veterinary Medical Association 198, 271-272 De Decker, S., Davies, E., Benigni,L. et al. (2012) Surgical treatment of an intracranial epidermoid cyst in a dog. Veterinary Surgery 41, 766-771 Ellison, G. W., Donnell, R. L. & Daniel, G. B. (1995) Nasopharyngeal epidermal cyst in a dog. Journal of the American Veterinary Medical Association 207, 1590-1592 Featherstone,H. & Llabres Diaz, F. (2003) Maxillary bone epithelial cyst in a dog. Journal of Small Animal Practice 44, 541-545 Gormley, W. B., Tomecek, F. J., Qureshi, N., et al. (1994) Craniocerebral epidermoid and dermoid tumours: a review of 32 cases. Acta Neurochirurgica 128, 115-121 Koch, D.A., Arnold, S., Hubler, M. et al. (2003) Brachycephalic syndrome in dogs. Compendium on Continuing Education for Practicing Veterinarians 25, 48-55 Lipitz, L., Rylander, H. & Pinkerton, M.E. (2011) Intramedullary epidermoid cyst in the thoracic spine of a dog. Journal of the American Animal Hospital Association 47, e145-e149 MacKillop, E., Schatzberg, S. J. & De lahunta, A. (2006) Intracranial epidermoid cyst and syringohydromyelia in a dog. Veterinary Radiology and ultrasound 47, 339-344 Oechtering, G. U. (2010) Brachycephalic syndrome- new information on an old congenital disease. Veterinary Focus 20(2), 2-9 Oechtering, T. H., Oechtering, G. U. & Noeller, C. (2007) Computed tomographic imaging of the nose in brachycephalic dog breeds. Tieraerztliche Praxis 35, 177-87 Platt, S. R., Graham, J., Chrisman, C. L. et al.(1999) Canine intracranial epidermoid cyst. Veterinary radiology and ultrasound 40, 454-458 Priddy, N. H., Pope, E. R., Cohn, L. A., et al. (2001) Alveolar mucosal approach to the canine nasal cavity. Journal of the American Animal Hospital Association 37, 179-182 Rostel, C. T. & Frankel, D. J. (2010) Punch resection alaplasty technique in dogs and cats with stenotic nares: 14 cases. Journal of the American Animal Hospital Association 46, 5-11 Shamir, M. H., Lichosky, D., Aizenberg, I., et al. (1999) Partial surgical removal of an intramedullary epidermoid cyst from the spinal cord of a dog. Journal of Small Animal Practice 40, 439-442 Steinberg, T., Matiasek, K., Bruehschwein, A., et al. (2007) Imaging diagnosis— intracranial epidermoid cyst in a Doberman Pinscher. Veterinary Radiology and Ultrasound 48, 250-253 Tomlinson, J., Higgins, R. J., LeCouteur, R. A., et al. (1988) Intraspinal epidermoid cyst in a dog. Journal of the American Veterinary Medical Association 193 (11), 1435-1436 Verstraete, F. J. M., Zin, P. B., Kass, P. H., et al. (2011) Clinical signs and histologic findings in dogs with odontogenic cysts: 41 cases (1995-2010). Journal of the American Veterinary Medical Association 239, 1470-1476 Watanabe, K., Kadosawa, T., Ishiguro, T., et al. (2004) Odontogenic cysts in three dogs: one odontogenic keratocyst and two dentigerous cysts. Journal of Veterinary Medical Science 66(9), 1167-1170
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CASE REPORT
Intranasal epidermoid cyst causing upper airway obstruction in three brachycephalic dogs D. Murgia, M. Pivetta, K. Bowlt, C. Volmer, A. Holloway and R. Dennis Animal Health Trust, Centre for Small Animal Studies, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
This case report describes three brachycephalic dogs with intranasal epidermoid cysts that were causing additional upper airway obstruction. Although epidermoid cysts have been described in several locations in dogs, to the authors’ knowledge intranasal epidermoid cysts have not been previously reported. All dogs had mucopurulent to haemorrhagic nasal discharge. Magnetic resonance imaging of the head revealed the presence of unilateral or bilateral intranasal cystic lesions obstructing the nasal cavities partially or completely, with atrophy of the ipsilateral nasal turbinates. The cystic lesions were surgically excised in all dogs using a modified lateral alveolar mucosal approach to the affected nasal cavity. Aerobic, anaerobic and fungal culture of the cystic contents were negative and histology of the excised tissue was consistent with a benign intranasal epidermoid cyst in each dog. Upper airway obstruction was clinically improved in two dogs. Journal of Small Animal Practice (2014) 55, 431–435 DOI: 10.1111/jsap.12215 Accepted: 27 February 2014; Published online: 3 April 2014
additional upper airway obstruction and contributing to the BAOS exhibited by each.
INTRODUCTION The typical anatomical abnormalities leading to respiratory distress in brachycephalic breeds include stenotic nares, elongated and hyperplastic soft palate, narrowed rima glottidis, tracheal hypoplasia and laryngeal collapse (Koch et al. 2003). Recent studies have demostrated that additional constrictions in the upper airway including severe intranasal deformities such as hyperplastic turbinates contribute to brachycephalic airway obstructive syndrome (BAOS) (Oechtering et al. 2007). Excessive selection for extremes of conformation has led to deformity of the entire upper respiratory tract leading to stenosis of the nasal vestibule caused by the inner part of the nasal wing, nasal and nasopharyngeal obstruction due to hyperplastic and dysplastic conchae, nasopharyngeal collapse and laryngomalacia (Oechtering et al. 2007). It has been reported that shortening of the craniofacial skull and thus of the nasal cavity leads to rostral aberrant conchae (RAC) resulting in obstruction of the nasal passage and to caudal aberrant conchae (CAC) resulting in obstruction of the nasopharyngeal meatus (Oechtering et al. 2007, Oechtering 2010). These severe intranasal deformities in brachycephalic dogs are the basis for new pathophysiological understanding of BAOS. This case report serves to describe three brachycephalic dogs with intranasal epidermoid cysts that were causing Journal of Small Animal Practice
•
Vol 55
•
August 2014
•
CASE HISTORIES A four-year-old entire male English bulldog (dog 1) was referred to the Centre for Small Animal Studies of the Animal Health Trust for assessment of a 5-month history of right unilateral nasal discharge and mild epistaxis. Coughing, lethargy and occasional pyrexia had been poorly responsive to antibacterial therapy. Previous aerobic, anaerobic and fungal culture of nasal discharge yielded Pseudomonas eaeruginosa. Upon presentation, all cardinal signs were within reference intervals. Right muco-purulent nasal discharge and brachycephalic syndrome-related respiratory signs were noted. Furthermore, absence of airflow through the right nasal passage was observed. Rhinoscopy revealed right nasal meatus occlusion by a multilobulated mass. A magnetic resonance imaging (MRI) scan of the head was then performed and an oval cystic mass lesion 36 mm (length, L) × 21 mm (height, H) × 26 mm (width, W) occupying the ventral two-thirds of the right nasal cavity between the root of the right maxillary canine and the ethmoturbinates was observed. The cyst contents were homogeneously hypointense in T1 weighted (T1W) images, hyperintense in T2-W (T2W) images (Fig 1a to c) and with a 3 to 4 mm thick, hypointense wall which enhanced moderately post
© 2014 British Small Animal Veterinary Association
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D. Murgia et al.
(a)
(b)
(c)
FIG 1. (a to c) Four-year-old male English bulldog (dog 1). (a) Sagittal T2-W, (b) dorsal T2-W and (c) transverse T2-W images of the head showing an oval cystic lesion (black arrow) filling the right nasal chamber extending from the right maxillary canine tooth to the ethmoturbinates. The cyst contents are homogeneously hyperintense. The osseous boundary of the nasopharyngeal meatus and the maxillary recess are destroyed (c). The cyst occludes the right nasopharyngeal meatus with consequent complete filling of the right frontal sinus (black asterisk), of the right maxillary recess and nasal turbinate interspace (black arrow head) with hyperintense secretions (a and c). The left intact maxillary recess is identified with a white asterisk (c)
contrast. The cyst obstructed the right nasopharyngeal meatus, with consequent complete filling of the right frontal sinus and nasal turbinate interspace with hyperintense secretions. A three-year-old entire male pug (dog 2) was referred to the Centre for Small Animal Studies of the Animal Health Trust for progressively increasing upper respiratory noises consistent with BAOS. Upon presentation, stenotic nares and bilateral nasal serous discharge associated with open mouth breathing were observed. At rhinoscopy left nasal chamber occlusion could be visualised. An MRI scan of the head revealed complete occlusion of the left nasal cavity for much of its length by a cystic structure 23 mm (L) × 9 mm (H) × 18 mm (W). Rostrally it surrounded the root of the left maxillary canine and caudally it extended into the common nasal meatus. Laterally, the maxillary recess appeared to be included in the cyst and the nasal septum was intact. A three-year-old neutered male pug (dog 3) was presented as an urgent referral with a 2-year history of upper respiratory dysfunction and episodes of apparent collapse over the preceding 432
48 hours. The dog had been diagnosed with a hiatal hernia and BAOS and had undergone a folding flap palatoplasty, alaplasty and everted laryngeal saccule removal 1 year before presentation. Over the few months before referral, deterioration of the brachycephalic syndrome related signs and purulent nasal discharge were reported. On the basis of physical examination and history, syncope secondary to upper airway obstruction was the initial suspect diagnosis. Rhinoscopy showed only occlusion of the right nasal chamber. An MRI scan of the head revealed a thin-walled, cystic structure 18 (L) × 12 (H) × 14 (W), filling the right nasal chamber and obstructing the choanae. The cyst, appeared to arise and to surround the caudal aspect of the right maxillary canine and first premolar tooth roots. The nasal turbinates on this side could not be recognised. Assessment of the upper airways under general anaesthesia revealed breed-associated elongation of the soft palate, bilateral laryngocoele and stenotic nares in dog 1, therefore staphylectomy, removal of the everted saccules and punch resection alaplasty was performed (Rostel 2010). Dog 2 also demonstrated
Journal of Small Animal Practice
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Vol 55
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August 2014
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© 2014 British Small Animal Veterinary Association
Intranasal epidermoid cyst in brachycephalic dogs
an elongated soft palate and tonsillar enlargement which were surgically corrected by staphylectomy and bilateral tonsillectomy. Surgical exploration using an alveolar mucosal approach to the affected nasal cavities was performed in all dogs (Priddy et al. 2001). A pharyngeal pack was placed to prevent inadvertent aspiration of blood or flushing fluids and dogs were positioned in lateral recumbency. A modification of the described technique was necessary to gain access to the lateral nasal chambers. Dog 1 underwent right lateral rhinotomy, dog 2 bilateral rhinotomy and dog 3 a left lateral rhinotomy. The lateral aspect of the maxillary bone was palpated and using a number 11 scalpel blade an incision was made through the maxillary gingival border from the caudal aspect of the canine to the fourth pre-molar tooth. Using a Freer periosteal elevator, in dogs 1 and 2 (left rhinotomy), the mucosa was elevated from the bone allowing the visualisation of a discoloured area associated with osteoatrophy of the maxilla delineating the lateral nasal cavity (Fig 2). Underneath,
FIG 2. Four-year-old male English bulldog (dog 1). Lateral alveolar mucosal approach to the right nasal cavity. Dorsal gingival mucosa elevation reveals discoloured and atrophic maxillary bone
FIG 3. Four-year-old male English bulldog (dog 1). Lateral alveolar mucosal approach to the right nasal cavity. Underneath the maxillary bone, following enlargement of the bony defect the opened cyst wall is visible Journal of Small Animal Practice
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the cyst was visible and was opened by the use of an artery forceps (Fig 3). During right lateral rhinotomy in dogs 2 and 3 maxillary bone atrophy was not encountered and a 1-mm intramedullary pin was used to create a hole into the nasal passage just caudal to the root of the maxillary canine. A series of increasing diameter pins and Smith Kerrison forceps were then used to enlarge the initial hole. The entire wall of the cyst was excised using a curette (Fig 4) and submitted for aerobic/anaerobic culture and histopathology (Fig 5). After complete excision of the cysts the interior of the rostral nasal cavities could be visualised. These were tested for patency by passing a fine silicone feeding tube into the nasopharynx and were flushed with sterile saline before closure. The rhinotomy was closed by apposing the alveolar mucosa with 4-0 Poliglecaprone 25 (Monocryl suture; Ethicon) in a simple interrupted pattern. Culture of the cystic fluid did not yield bacteria and results of histopathological evaluation of the removed tissue were consistent with an epidermoid cyst based on the classification published by Featherstone & Llabres Diaz (2003).
FIG 4. Three-year-old male pug (dog 3). Lateral alveolar mucosal approach to the right nasal cavity. Excision of the cyst wall
FIG 5. Three-year-old male pug (dog 3). Completely removed cyst
© 2014 British Small Animal Veterinary Association
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(a)
(b)
FIG 6. (a) Three-year-old male pug (dog 3). Histology of the cyst at low magnification. Area showing the pseudostratified columnar ciliated and mucous nasal epithelium (black arrow). Below this the stroma with inflammatory cell infiltration (black arrow-head) and the epidermoid cyst wall with the stratified squamous epithelium and discrete keratinisation (white arrow). The white arrow-head identifies some bone trabeculae (H&E. ×1). (b) Three-year-old male pug (dog 3). Histology of the cyst on high magnification. The cyst wall consists of a slightly keratinised stratified squamous epithelium and lies on a fibrous inflammatory stroma. The black arrow-head identifies the thin parakeratotic layers whereas the white-arrow head shows the spinous layers (H&E. ×20)
In all cases, a benign cystic structure within the nasal mucosa was found. The wall of this cyst consisted of a regular stratified squamous epithelium composed of a basal cuboidal layer, spinous layers and thin parakeratotic layers (Figs 6a, b). Epithelial cells were well differentiated. The lumen of the cysts contained sloughed epithelial cells, red blood cells and variable numbers of neutrophils and macrophages. The surrounding stroma was fibrous and infiltrated by variable numbers of inflammatory cells (lymphocytes, plasma cells and neutrophils). Dogs 1 and 3 recovered uneventfully from general anaesthesia and surgery and showed immediate relieve of upper respiratory obstruction signs. Dog 2 developed cardiorespiratory arrest following regurgitation and aspiration pneumonia during anaesthesia and died.
DISCUSSION This case series describes the diagnosis and surgical treatment of intranasal epidermoid cysts in three brachycephalic dogs that may have caused exacerbation of pre-existing signs of upper airway obstruction. In dogs epidermoid cysts have previously been reported in multiple locations which include the medial canthus of the eye (Davidson & Blanchard 1991), intracranially (Gormley et al. 1994, Platt et al. 1999, MacKillop et al. 2006, Steinberg et al. 2007, De Decker et al. 2012), the spinal cord and canal (Tomlinson et al. 1988, Shamir et al. 1999, Cappello et al. 2006, Lipitz et al. 2011) and in the nasopharynx (Ellison et al. 1995). To the authors’ knowledge, there have been no published reports of intranasal epidermoid cysts in the dog. Rhinoscopy identified different degrees of nasal chamber occlusion but did not add information regarding the nature of the obstruction, whereas the MRI scans permitted the identification of abnormal cystic structures associated with a partial or complete occlusion of the nasal passage. The differential diagnosis for cystic structures in this area included pure inflammatory lesions such as maxillary bone 434
epithelial cysts, dermoid cysts, dentigerous cysts, radicular cysts and canine odontogenic parakeratinised cysts (COPCs). These can be distinguished from one another by comparing the nature of the cellular component and the cyst content. Epithelial cysts have a simple non-stratified epithelial lininig and usually contain fluid of low cellularity (Featherstone & Llabres Diaz 2003). However, epidermoid cyst are a type of epithelial cyst that has a stratified, keratinised squamous epithelium and contains intraluminal breakdown products of desquamated epithelial cells (Davidson & Blanchard 1991, Featherstone & Llabres Diaz 2003). Epidermoid cysts can result from congenital sequestration of epithelial tissue, trauma or a foreign body reaction and are typically associated with a predominant inflammatory component that is absent in simple epithelial cysts (Davidson & Blanchard 1991). Finally, dermoid cysts are also lined by a stratified squamous epithelium but generally contain dermal appendages such as hair and sebaceous glands (Gormley et al. 1994). Dentigerous, radicular cysts and COPCs are subtypes of odontogenic cysts. Verstraete (2011) reported that over 50% of dogs presenting with odontogenic cysts were brachycephalic. The reason for the apparent high frequency of odontogenic cysts in these breeds is unknown, although crowding of the teeth as a result of cephalic conformation may be an underlying factor (Verstraete et al. 2011). Histopathological examination of dentigerous and radicular cysts in dogs shows the presence of a cyst lining of non-keratinised stratified squamous epithelium (Watanabe et al. 2004). By contrast, COPC histopathological features are consistent with stratified squamous epithelium of uniform thickness showing some parakeratinisation (Verstraete et al. 2011). Invasive dentigerous and radicular cysts typically surround respectively the crown of an unerupted tooth and the apex of a non-vital tooth. While COPCs, mainly identified in the maxilla, surround the roots of fully erupted, normally developed teeth and are characterised by locally infiltrative growth as seen in the present cases (Verstraete et al. 2011). On the basis of the classification of the general features of cystic structures reported by Featherstone & Llabres Diaz (2003), the
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histopathological findings of the three reported intranasal cysts were consistent with epidermoid cysts. Like epidermoid cysts, the lesions described here were space-occupying, slowly expanding, painless and fluid-filled cysts. However, they surrounded healthy maxillary tooth roots as COPCs are described to do (Verstraete et al. 2011). Their origin and aetiopathogenesis is therefore still unclear as the described epidermoid cysts and COPCs are similar in localisation, behaviour and histology. If not surgically removed they may become larger and cause pressure damage to the local surrounding tissues; neighbouring teeth may become displaced and maxillary/mandibular bone may become weakened and prone to fractures (Baxter 2004). Excision of the entire cyst wall and curettage is therefore essential (Baxter 2004). The intranasal cysts described in the brachycephalic dogs in this report strongly suggest that MRI or computed tomography (CT) of the upper respiratory airways should be considered as part of the diagnostic work-up in selected brachycephalic dogs. This would allow abnormalities which are part of a more complex form of upper airway obstructive syndrome to be detected and would permit better surgical planning. Surgery was performed to remove the cysts, restore nasal patency and relieve the upper airway obstruction, allowing better air flow. The lateral alveolar mucosal surgical approach to the affected nasal cavities was less invasive than a dorsal or ventral rhinotomy. It was felt that surgical approach via interventional rhinoscopy would not have provided adequate exposure of the cysts. The intranasal epidermoid cysts described in this report should be included as a differential diagnosis when assessing brachycephalic breeds presenting with clinical signs associated with BAOS and should be considered as contributing factor in the complex pathogenesis of the syndrome. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper.
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