Equine Nasal and Paranasal Sinus Tumours: Part 2: A Contribution of 28 Case Reports

The clinical and pathological findings of 28 cases (27 horses, 1 donkey) of equid sinonasal tumours examined at the Edinburgh Veterinary School are presented and include: seven cases of squamous cell carcinoma (SCC); five adenocarcinomas; three undifferentiated carcinomas; two adenomas; five fibro-osseous and bone tumours; and single cases of ameloblastoma, fibroma, fibrosarcoma, undifferentiated sarcoma, melanoma and lymphosarcoma. The median ages of animals affected with epithelial, and fibro-osseous/bone tumours were 14 and 4 years, respectively. Unilateral purulent or mucopurulent nasal discharge (81% of cases) and gross facial swellings (82% of cases) were the most common presenting signs with sinonasal tumours, with epistaxis recorded in just 23% of cases. Radiology and endoscopy were the most useful ancillary diagnostic techniques. The maxillary area was the most common site of tumour origin, and only three cases were definitively identified as originating in the nasal cavity. Four of the maxillary SCC lesions originated within the nasal cavities or maxillary sinuses, while two originated in the oral cavity. Fourteen of 15 carcinomas, but only two of the 13 remaining tumours, spread to other sites in the head. Only three cases of sinonasal tumour had lymph node metastases, and none had distant metastases. In the long term, surgical treatment with seven malignant tumours was unsuccessful (6 months median survival post-operatively), but was successful with four out of five benign tumours (no regrowth at a median of 4 years post-operatively).     

USING SEMI‐AUTOMATED SEGMENTATION OF COMPUTED TOMOGRAPHY DATASETS FOR THREE‐DIMENSIONAL VISUALIZATION AND VOLUME MEASUREMENTS OF EQUINE PARANASAL SINUSES

The system of the paranasal sinuses morphologically represents one of the most complex parts of the equine body. A clear understanding of spatial relationships is needed for correct diagnosis and treatment. The purpose of this study was to describe the anatomy and volume of equine paranasal sinuses using three‐dimensional (3D) reformatted renderings of computed tomography (CT) slices. Heads of 18 cadaver horses, aged 2–25 years, were analyzed by the use of separate semi‐automated segmentation of the following bilateral paranasal sinus compartments: rostral maxillary sinus (Sinus maxillaris rostralis), ventral conchal sinus (Sinus conchae ventralis), caudal maxillary sinus (Sinus maxillaris caudalis), dorsal conchal sinus (Sinus conchae dorsalis), frontal sinus (Sinus frontalis), sphenopalatine sinus (Sinus sphenopalatinus), and middle conchal sinus (Sinus conchae mediae). Reconstructed structures were displayed separately, grouped, or altogether as transparent or solid elements to visualize individual paranasal sinus morphology. The paranasal sinuses appeared to be divided into two systems by the maxillary septum (Septum sinuum maxillarium). The first or rostral system included the rostral maxillary and ventral conchal sinus. The second or caudal system included the caudal maxillary, dorsal conchal, frontal, sphenopalatine, and middle conchal sinuses. These two systems overlapped and were interlocked due to the oblique orientation of the maxillary septum. Total volumes of the paranasal sinuses ranged from 911.50 to 1502.00 ml (mean ± SD, 1151.00 ± 186.30 ml). 3D renderings of equine paranasal sinuses by use of semi‐automated segmentation of CT‐datasets improved understanding of this anatomically challenging region.     

CT and cross-sectional anatomy of the paranasal sinuses in the Holstein cow

The structure of paranasal sinuses in cattle is difficult to understand due to its complexity, age-related changes, and insufficient published data. In this prospective, anatomic study, we described the anatomy of the paranasal sinuses in the Holstein cow using computed tomography (CT) and cross-sectional anatomic slices. Twelve healthy adult Holstein cow heads were used for this study. The heads were scanned using CT, and frozen anatomical sections were taken. The locations, borders, and relationships of the paranasal sinuses were defined on the anatomical sections and CT images. The paranasal sinuses on each side of the head consisted of conchal (dorsal, middle, and ventral), maxillary, lacrimal, palatine, frontal, sphenoid sinuses, and ethmoidal cells. The frontal sinus pneumatized all bones surrounding the cranial cavity, except for the ethmoidal and body of basisphenoid bones. The sphenoid and ventral conchal sinuses were the most asymmetrical, and the middle conchal sinus was the simplest. The ventral conchal sinus was detected in eleven animals, one of which was unilateral. This sinus communicated with the middle nasal meatus (13/21) and ventral nasal meatus (8/21). Findings can be used as background for interpreting CT studies of cattle with clinical signs of sinonasal region diseases. Future cross-sectional radiological and reconstructive anatomical studies and investigation of the postnatal development of related structures in cattle are needed.     

Retrospective review of 50 canine nasal tumours evaluated by low-field magnetic resonance imaging

OBJECTIVES: Low-field magnetic resonance imaging machines are being used more often in veterinary practice for the investigation of sinonasal disease. The aim of this retrospective study was to describe and characterise the low-field magnetic resonance imaging features of nasal tumours in dogs. METHODS: The Queen's Veterinary School Hospital magnetic resonance imaging database (2001-2005) was searched for dogs with a magnetic resonance imaging diagnosis of a nasal tumour. Fifty cases with histological diagnosis of nasal tumour were found. The appearance and extent of the nasal tumour as well as the involvement of adjacent anatomic structures were examined against a checklist. RESULTS: The most common magnetic resonance imaging findings were as follows. (1) Soft tissue mass replacing the destroyed nasal conchae and/or ethmoturbinates (98 per cent of cases). (2) Nasal septum destruction (68 per cent of cases). (3) Retained secretions with or without mass caudally in frontal sinuses (62 per cent of cases). (4) Nasal/frontal bone destruction (52 per cent of cases). Low-field magnetic resonance imaging allowed differentiation of tumour tissue from retained secretions or necrotic tissue. Magnetic resonance imaging was invaluable in assessing the extension of the tumour into the maxillary recesses, caudal recesses, nasopharynx, adjacent bones and cranial cavity. The tumour often extended caudally into the frontal sinuses, nasopharynx and perhaps most importantly into the caudal recesses. Tumour extension into the cranial cavity was not common (16 per cent), and only three of these cases showed neurological signs. However, 54 per cent of cases showed focal meningeal (dural) hyperintensity, although the significance of this is unclear. A significant difference (P<0.05) in tumour signal intensity between the sarcomas and carcinomas was found. CLINICAL SIGNIFICANCE: The use of a low-field magnetic resonance imaging technique is excellent for the diagnosis and determination of extent of sinonasal tumours.     

Clinical anatomy of the equine sphenopalatine sinus

REASONS FOR PERFORMING STUDY: Disorders of the equine sphenopalatine sinus, including empyema and neoplasia, have been reported to cause damage to cranial nerves II and V. However, the clinical anatomy of these sinuses is not well described in horses. OBJECTIVE: To examine the anatomy of the sphenopalatine sinuses in a range of equidae and, in particular, to examine the relationship of these sinuses to adjacent major nerves and vessels. METHODS: The anatomy of the sphenoidal and palatine paranasal sinuses was examined in 16 equidae, primarily using transverse skull sections. Relevant structures were documented and photographed. RESULTS: There was much variation between individual horses in sphenopalatine sinus anatomy. The sphenoidal sinuses were small in young horses and appeared to become larger and more complex with age. Variation was present in the extent that the sphenopalatine sinus extended into the basisphenoid bone. The septum dividing left and right sphenoidal sinuses was frequently not midline, but was intact in all cases. The sphenoidal and palatine sinuses communicated in most horses. In such cases, what could accurately be termed the (combined) sphenopalatine sinuses usually drained directly into the caudal maxillary sinuses. Additionally, in 5 out of 16 cases, some compartments of the sphenoidal sinus also drained into the ethmoidal sinus. The dorsal and lateral walls of the sphenoidal sinus were very thin and directly adjacent to cranial nerves II, III, IV, V and VI and major blood vessels. CONCLUSIONS: The equine sphenoidal and palatine sinuses are very variable in their anatomy, but are always in close proximity to multiple cranial nerves and major blood vessels. POTENTIAL RELEVANCE: Many cranial nerves and blood vessels could be damaged with disorders involving the sphenopalatine sinus, potentially causing major and variable neurological syndromes, haemorrhage and extension of sepsis.     

A review of equine paranasal sinusitis. Aetiopathogenesis,clinical signs and ancillary diagnostic techniques

The equine paranasal sinuses are air filled cavities of uncertain function that are susceptible to inflammation, usually associated with bacterial infection. A common feature of most types of sinusitis is the accumulation of exudate within the affected sinus and subsequent ipsilateral nasal discharge. Equine sinusitis can have a variety of causes, including primary sinusitis following upper respiratory tract infections, and secondary sinusitis caused by dental infections, intrasinus benign and malignant growths and head trauma.     

Surgical anatomy of the nasal and paranasal sinuses in Egyptian native sheep (Ovis aries) using computed tomography and cross sectioning

The present work aimed to describe the normal computed tomography (CT) and cross‐sectional anatomy of the nasal and paranasal sinuses in sheep and to correlate these features with the relevant clinical practices. Twenty apparent healthy heads of Egyptian native breed of sheep (Baladi sheep) of both sexes were used for studying these sinuses. CT images and their closely identical cross sections of the same head were selected and serially labelled in a progression from the rostral nasal region to the caudal aspect of the head using cheek teeth as landmarks. The current investigation reported seven sinuses in sheep, including maxillary, frontal, lacrimal and sphenoidal as paranasal, as well as dorsal and middle conchal and ethmoidal as nasal with unnoticeable palatine and ventral nasal conchal sinuses. The boundaries, extension, structure and communications of these sinuses were fully described. The current study provided anatomical guidelines for surgical interference in the frontal and maxillary sinuses during trephination, dehorning and sinuscopy. Also, an acceptable anatomical explanation was reported in this study for the high incidence of maxillary sinusitis than other sinuses. CT and cross‐sectional anatomy could be used as helpful database for diagnosis and clinical interference of the nasal and paranasal sinuses in sheep.     

Radiographic examination of the facial, nasal and paranasal sinus regions of the horse: I. Indications and procedures in 235 cases

The radiographic procedures used for examination of the facial area and paranasal sinuses of 235 horses are reported. Clinical indications for these examinations and the diagnoses made are reviewed. Unilateral nasal discharge was the commonest reason for radiography, accounting for about one third of cases, most of which had radiological signs of paranasal sinus disease recognisable on erect lateral films. Oblique projections were required to obtain further information about the maxillary dental arcades and ventro-dorsal views demonstrated sinus expansion and extension of disease into the nasal cavity. In 24 horses with bilateral nasal discharge, the origin was usually shown to be in the lower respiratory tract and radiographic abnormalities were found in only 20 per cent of cases. Facial swelling was a feature of 25 per cent of cases; the commonest causes were premolar periapical disease, best shown on oblique views with the patient recumbent, and suture periostitis, easily demonstrated on erect lateral films. Other causes of facial swelling, which required multiple radiographic projections for evaluation, were sinus cysts and tumours and peripheral soft tissue masses. Epistaxis for which no cause could be found in the lower respiratory tract was the indication for radiography in a further 10 per cent of cases. In almost half of these a radiopaque shadow representing an ethmoid haematoma could be seen on an erect lateral film. A sinus cyst and a tumour were also recorded but most other causes of epistaxis failed to produce radiographic signs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Histological and computed tomographic characteristics of the sinonasal structure of BALB/c mice

Mice models were used to study the pathogenesis of mice and human diseases. Although some mice models of allergic rhinitis and rhinosinusitis have been reported, no detailed anatomic, histological and computed tomographic comparative data of the normal murine sinus are available in the literature for new researchers to establish mice models. The purpose of this study was to clarify the histological and computed tomographic characteristics of the normal nasal sinus in BALB/c mice. Fifteen sinonasal specimens were collected. Five mice were subjected to micro-computed tomography imaging, and then dissected to observe its anatomic landmarks, and 10 mice were subjected to haematoxylin and eosin staining. Important anatomic landmarks were clearly demonstrated, including the ethmoturbinates, nasoturbinal, maxilloturbinate, ethmoid sinus, maxillary sinus, nasopharyngeal duct, nasolacrimal duct and vomeronasal organ. Full and typical sinonasal landmarks can be visualized by gross anatomy, micro-computed tomography imaging and haematoxylin and eosin staining, which will be useful for establishing the mouse models of nasal disease.     

Computed tomographic appearance of equine sinonasal neoplasia

The computed tomography (CT) features of tumors involving the nasal cavity and/or paranasal sinuses of 15 horses were reviewed. The 15 tumors included five neuroendocrine tumors/neuroblastomas, two undifferentiated carcinomas, two myxosarcomas, and one each of nasal adenocarcinoma, hemangiosarcoma, chondroblastic osteosarcoma, anaplastic sarcoma, myxoma, and ossifying fibroma. All tumors except the ossifying fibroma were iso- or hypoattenuating relative to masseter muscle. Thirteen of the fifteen tumors exhibited moderate or marked osteolysis of adjacent cortical bone and 14/15 were characterized by destructive changes of the nasal turbinates, nasal septum, and/or infraorbital canal. Ten horses had moderate or marked involvement of the cribriform plate and six had clear intracranial extension of the mass. CT features were compared to radiographic findings for 10 horses. A mass was observed in 10/10 radiographic studies and mass within the caudal maxillary sinus (7/8) and rostral maxillary sinus (6/7) was identified correctly in most horses. The radiographs were least sensitive for identifying masses within the sphenopalatine sinus (0/5), cranium (0/4), and retrobulbar space (1/7) compared to CT. The radiographs also underestimated potential features of malignancy, such as severity of osteolysis or osseous production. While radiographs are a useful screening tool for identification of sinonasal masses, CT provides greater information regarding mass extent, features of malignancy, and important prognostic indicators.     

A Large Frontonasal Bone Flap for Sinus Surgery in the Horse

A large frontonasal bone flap was created to treat diseases of the paranasal sinuses in 14 horses. The bone flap was made as wide as possible within the confines of the nasolacrimal duct so the floor of the frontal sinus and the dorsal and ventral conchae could be opened. These openings exposed the nasal passages, maxillary sinuses, and ventral conchal sinus thereby facilitating removal of diffuse and localized lesions from these sites. Diseases treated were ethmoid hematomas (4 horses), sinus cysts (5 horses), cryptococcal granuloma, osteoma, hemangiosarcoma, pus in the ventral conchal sinus, and periapical infection of a second molar. Four horses were euthanatized during or after surgery, one because of postsurgical pleuritis and pneumonia (horse with osteoma) and three because of their primary problems (cryptococcal granuloma, hemangiosarcoma, pus in the ventral conchal sinus). Skin suture abscesses that responded to treatment developed in four horses. Ten horses returned to their intended uses, the sinus flaps healed without blemish, and the original problems did not recur. The frontonasal flap technique provided greater access to all paranasal sinuses than methods described previously.     

Peripheral nerve sheath tumour of the equine maxillary sinus

This case report describes an 8‐year‐old Belgian Warmblood mare that was initially diagnosed and treated for a dental sinusitis. Despite removal of the diseased teeth and appropriate treatment, the sinusitis did not resolve. Over time, growth of a peripheral nerve sheath tumour of the left maxillary sinus became apparent, with recurrence after surgical removal. The clinical, radiographic, computed tomography, magnetic resonance imaging and pathological (gross and histological) findings of the first reported peripheral nerve sheath tumour of the equine paranasal region are described and illustrated.     

Calcified tumours of the paranasal sinuses in three horses

Three horses, a 10-year-old Thoroughbred mare, a 9-year-old Thoroughbred gelding and a 6-year-old Arab gelding, with calcified tumours of the paranasal sinuses, are described. All horses presented with purulent nasal discharges and facial distortion. Exophthalmos, blepharospasm and ocular discharge were also a feature in individual horses. A presumptive diagnosis of a calcified tumour was made on the basis of clinical signs and radiographic and endoscopic findings. The tumours ranged from 15 to 25 cm in diameter. A large frontonasal bone flap was used to expose the tumours, which were cleaved into several pieces with an osteotome and removed. Histological examination of the masses identified cementomas in two cases and an osteoma in the third. Long term follow up from 18 months to 5 years after surgery indicated that there was no recurrence. This case series demonstrates that, although calcified tumours of the paranasal sinuses are rare in horses, they should be considered in the differential diagnosis of purulent nasal discharge, facial swelling and ocular distortion, and are amenable to surgical treatment.     

COMPUTED TOMOGRAPHIC IMAGING OF THE EQUINE HEAD

The head from three horses euthanized due to diseases unrelated to the head and neck was imaged using computed tomography (CT). Gross cross-sectional slices of equine head #1 and skeleton of equine head #2 were compared with the CT images of the three equine heads to identify normal structures of the cranium, brain, paranasal sinuses, nasal cavity, and teeth. Labeled transverse CT images of the equine head are presented sequentially as a reference for normal anatomy.     

Evaluation of a novel post operative treatment for sinonasal disease in the horse (1996-2007)

Reasons for performing study: Results of surgical treatment of sinonasal disease in horses have been reported previously; however, this paper describes the outcome of horses in which a specific post operative treatment protocol was used. Objectives: The objectives of the study were to determine: 1) short‐ and long‐term outcome; 2) complications; and 3) recurrence rates of different disease processes, when horses were treated with a specific treatment protocol. Methods: Medical records of horses presented for surgical treatment of sinonasal disease from 1996–2007 were reviewed. Results and duration of surgical exploration were recorded. Post operatively, the sinus flaps were re‐opened with the horses standing and sedated. Number of horses requiring further treatment (debridement and/or lavage), median number of post operative days when the flap was re‐opened, median number of times the flap was opened and median duration of hospitalisation were recorded. Short‐ and long‐term survival and complication rates were determined. Results: Ninety‐one horses were included in the study. The sinus flaps were re‐opened with the horses standing a median of 3 days post operatively. Thirty‐nine horses (43%) required further treatment at this time and 89 horses (97%) survived to discharge. Incision infection was the most common complication encountered (29%). No horse required a blood transfusion. Recurrence rates were 5% for paranasal sinus cysts, 12% for progressive ethmoid haematoma and 50% for neoplasia. Conclusions: Rapid removal of the primary lesion followed by packing the sinuses and re‐evaluating in the standing horse in a more controlled environment offers a safe and effective means to thoroughly assess and treat sinonasal disease. Potential relevance: Surgical time, intraoperative haemorrhage, long‐term complications and recurrence rates of paranasal sinus diseases treated via frontonasal or maxillary sinus flap may be reduced using this technique.     

MAGNETIC RESONANCE IMAGING FEATURES OF SINONASAL DISORDERS IN HORSES

Diseases of paranasal sinuses and nasal passages in horses can be a diagnostic challenge because of the complex anatomy of the head and limitations of many diagnostic modalities. Our hypothesis was that magnetic resonance (MR) imaging would provide excellent anatomical detail and soft tissue resolution, and would be accurate in the diagnosis of diseases of the paranasal sinuses and nasal passages in horses. Fourteen horses were imaged. Inclusion criteria were lesions located to the sinuses or nasal passages that underwent MR imaging and subsequent surgical intervention and/or histopathologic examination. A low field, 0.3 tesla open magnet was used. Sequences in the standard protocol were fast spin echo T2 sagittal and transverse, spin echo T1 transverse, short‐tau inversion recovery (STIR) dorsal, gradient echo 3D T1 MPR dorsal (plain and contrast enhanced), spin echo T1 fatsat (contrast enhanced). Mean scan time to complete the examination was 53 min (range 39–99 min). Lesions identified were primary or secondary sinusitis (six horses), paranasal sinus cyst (four horses), progressive ethmoid hematoma (two horses), and neoplasia (two horses). The most useful sequences were fast spin echo T2 transverse and sagittal, STIR dorsal and FE3D MPR (survey and contrast enhanced). Fluid accumulation, mucosal thickening, presence of encapsulated contents, bone deformation, and thickening were common findings observed in MR imaging. In selected horses, magnetic resonance imaging is a useful tool in diagnosing lesions of the paranasal sinuses and nasal passages.     

Heterotopic polydontia as a cause for a cystic lesion in the paranasal sinus of a Thoroughbred filly

A 1-year-old Thoroughbred filly with left bony facial distortion was diagnosed with a multilobar expansile mass within the caudal maxillary and frontal sinuses on computed tomography (CT). Typical findings associated with a sinus cyst, including expression of amber fluid from the mass and a thick lining that could be peeled from the sinus walls, were found on surgical exploration of the sinus under general anaesthesia. Histological examination of firm structures within the fluid-filled cyst contained all components of embryologically normal dental tissue. The filly recovered well and entered training to race as a 2-year-old, as remodelling of the bony distortion and narrowing of the nasal passage was sufficient for airflow. Previous reports of paranasal cystic lesions in horses suggest developmental abnormalities as a causative factor, especially in young horses. Furthermore, heterotopic polydontia is reported as the underlying aetiology in some human paranasal sinus cysts. While polydontia has been reported in the paranasal sinuses and nasal passages of horses, this is the first case report that finds them associated with a cystic lesion within the paranasal sinus.     

Radiographic examination of the facial, nasal and paranasal sinus regions of the horse. II. Radiological findings

The radiographic findings in 167 horses subjected to radiography of the facial area, nasal cavity and paranasal sinuses are recorded. Cases were grouped according to clinical diagnosis and the common and disparate radiographic features between and within groups are discussed. Dental disease occurred most frequently and accounted for about 30 per cent of cases, most of which had periapical infection. This disorder presented as two distinct clinical entities in almost equal numbers affected teeth with roots rostral to the maxillary sinus usually produced facial swelling, whereas those with roots within the sinus were generally associated with nasal discharge as a result of secondary sinusitis. In the former group periapical changes could readily be identified on radiographs, but in the latter group affected teeth could be recognised with confidence in only about half the cases. Primary sinusitis was the commonest specific condition recorded and accounted for 32 cases, three of which were mycotic. Using lateral erect projections, comparison of the radiographic features of primary sinusitis and sinusitis secondary to dental disease showed some useful differentiating signs. In four ponies, rhinitis associated with sinusitis led to disruption of the intra-nasal structures but mycotic rhinitis, nasal ulceration and an intra-nasal foreign body produced no radiographic abnormalities. Sixteen cases of suture periostitis were recorded, with varying degrees of new bone formation, and of 13 animals presented for evaluation of trauma, pre-diagnosed fractures were demonstrated in 10 and complications due to sinusitis in three.(ABSTRACT TRUNCATED AT 250 WORDS)     

Osteoma of paranasal sinuses of a horse

A 2-year-old Quarter Horse gelding was examined for torticollis, facial protuberances over the frontal and maxillary sinuses, and persistent nasal discharge unresponsive to antibiotics. Radiograph revealed an osseous mass in the right paranasal sinuses. Histologic examination of the biopsied mass led to a diagnosis of osteoma. The mass was removed surgically in sections from the right frontal and maxillary sinuses through separate bone flaps, and sinuses were irrigated with saline solution for 8 days after surgery. Two weeks after surgery, radiography revealed small osseous opacities in the right paranasal sinuses. These opacities remained unchanged in radiographs obtained up to 23 months after surgery.