Ossifying fibroma in a miniature rex rabbit (Oryctolagus cuniculus)

In humans and animals, ossifying fibroma is a benign neoplasm that most frequently affects the mandible, often resulting in cosmetic deformities and malocclusion. It is considered rare in animals and most frequently affects young horses. A surgical biopsy of a solitary mass located beneath the gingiva in the right maxillary region, which had overgrown teeth and expanded the adjacent hard palate from a 6-year-old miniature Rex rabbit was submitted for light microscopic examination. The submitted incisional biopsy specimen was pale pink, firm, and nodular. Histopathologically, the neoplasm was composed of fibroblastic cells separated by abundant collagen. The neoplastic cells were interwoven with osteoblasts surrounding islands of mineralized, bony matrix containing few, widely spaced, often empty, lacunae. Minimal inflammation was present. Based on the histopathologic features, the tumor was diagnosed as an ossifying fibroma. To our knowledge, this is the first report of an ossifying fibroma in a rabbit.     

Equine paranasal sinus cysts: a report of 15 cases

The clinical and radiographic features of 15 cases of paranasal sinus cysts are described. Breed, sex and side frequency were unremarkable but two distinct categories of age incidence emerged. Onset of signs had occurred before one year of age in three cases, while all but two of the remaining 12 animals were older than nine years. The most common clinical signs were nasal airway obstruction, facial swelling and nasal discharge, often occurring in combination. Radiographic changes were recorded in all horses. Sinus opacification was a consistent finding and in several cases the bone surrounding the sinus had increased in thickness. Increase in intra-maxillary sinus pressure was demonstrated by septal displacement on ventro-dorsal radiographs in almost half the cases. Less common signs included expansion, free fluid accumulation within the affected sinus, dental distortion and displacement and mineralisation. Two horses were destroyed without treatment but in 13 animals surgical exploration was performed. Two of these were destroyed, one at the time of surgery and one five days postoperatively. In the remaining 11 cases, all accessible parts of the cyst were removed through a facial flap and drainage to the nasal meati was established. All these horses recovered satisfactorily and were followed up for periods between three months and six years without evidence of recurrence. Thirteen cysts arose in the caudal maxillary sinus and one each in the frontal and rostral maxillary compartments. Histopathological examination of portions of the cyst walls suggests that, like ethmoidal haematomas, they may originate from episodes of haemorrhage beneath the upper respiratory tract mucosa.     

Paranasal sinus masses of Rocky Mountain bighorn sheep (Ovis canadensis canadensis)

This article describes 10 cases of paranasal sinus masses in Rocky Mountain bighorn sheep (Ovis canadensis canadensis). Among 21 bighorns that were examined from 11 herds in Colorado, 10 individuals (48%) from 4 herds (36%) had masses arising from the paranasal sinuses. Affected animals included 9 of 17 females (53%) and 1 of 4 males (25%), ranging in age from approximately 2 years to greater than 10 years. Defining gross features of these masses included unilateral or bilateral diffuse thickening of the respiratory lining of the maxillary and/or frontal sinuses, with abundant seromucinous exudate in the affected sinus cavities. Defining histologic features of these masses included chronic inflammation and proliferation of mesenchymal and epithelial cells of the mucosa and submucosa. Epithelial changes included hyperplasia of mucosal epithelium, hyperplasia of submucosal glands and ducts, and neoplasia (adenocarcinoma). Mesenchymal changes included submucosal myxedema, submucosal fibroplasia/fibrosis, bone destruction, and neoplasia (myxomatous fibroma). Specific immunohistochemistry and polymerase chain reaction for Jaagsiekte sheep retrovirus and enzootic nasal tumor virus were performed with negative results.     

Urinary obstruction secondary to an ossifying fibroma of the os penis in a dog

A 13-year-old, 25-kg, castrated male border collie was referred for evaluation of pollakiuria, stranguria, and a decreased urine stream. A calcified periurethral mass near the caudal aspect of the os penis was identified on survey abdominal radiographs. A retrograde contrast urethrocystogram demonstrated that the mass was compressing the penile urethra. The mass was surgically resected. A histopathological diagnosis of an ossifying fibroma of the os penis was made. This report describes an atypical presentation of a rare tumor, an ossifying fibroma, that caused a urinary obstruction in a male dog. A review of the incidence, histopathological features, and behavior of ossifying fibromas is included.     

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)     

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)     

Paranasal Sinusitis Complicated by Inspissated Exudate in the Ventral Conchal Sinus

Primary paranasal sinusitis complicated by inspissated exudate within the ventral conchal sinus was diagnosed in five horses. Clinical signs included a unilateral, foul-smelling, mucopurulent nasal exudate of 2 to 7 months' duration. Two of the horses had partial nasal obstruction from distortion of the ventral concha. Radiographs of the skull showed a mass of soft tissue density dorsal to the roots of the superior third and fourth or fourth and fifth cheek teeth. Treatment included bone flap maxillary sinusotomy with exposure of the ventral nasal concha and removal of inspissated exudate. Resolution of the sinusitis occurred in all five horses.     

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.     

Rostral mandibulectomy in five horses.

Rostral mandibulectomy with primary gingival closure was performed in 5 horses with rapidly growing or bleeding mandibular tumors. The technique involved preservation of the most caudal portion of the mandibular symphysis to maintain stability. There were no surgical complications or recurrences, and the cosmetic and functional results were good. The histopathologic diagnosis of all the tumors was ossifying fibroma. Rostral mandibulectomy affords a simple and effective technique of treating tumors of the rostral portion of the mandible in horses.     

Repulsion of maxillary and mandibular cheek teeth in standing horses

Objective: To report the technique and results of cheek teeth repulsion in standing, sedated horses. Study Design: Case series. Animals: Horses (n=12), ponies (6). Methods: Medical records (2006–2009) of horses that had cheek tooth repulsion while standing were reviewed. Inclusion criteria included: maxillary or mandibular cheek tooth disease diagnosed by clinical and radiographic examination where attempted oral extraction failed necessitating repulsion. Horses were sedated and a local nerve block performed. Intraoperative radiographs facilitated instrument positioning and ensured repulsion of all dental remnants. Alveolar cavities were packed postoperatively and secondary dental sinusitis treated with lavage. Results: Median horse age was 7 years (range, 1–30 years). Maxillary (n=15) and mandibular (5) cheek teeth were removed successfully. One horse was euthanatized 1 week after tooth removal because of concurrent liver disease and 10 horses (59%) had resolution of discharge after the 1st treatment; 41% of extractions required follow‐up medical or surgical treatment to resolve signs [6/12 maxillary sinusitis and 1/5 persistent mandibular drainage]. Conclusions: Standing repulsion of diseased and fractured cheek teeth is an effective means of resolving clinical signs of dental disease when oral extraction fails. Chronic sinus involvement increased the risk of postextraction surgical treatment for sinusitis.     

CT FEATURES OF ALVEOLITIS AND SINUSITIS IN HORSES

Sinusitis is a common disorder in horses and may result from trauma, dental diseases, or space-occupying lesions. Radiography can only provide a limited amount of information. Computed tomography (CT) has been documented as an alternative imaging method. Eighteen horses (mostly Warmblood) with signs of chronic sinusitis were examined preoperatively with CT to assist in diagnosis of the underlying cause. There was a group of common CT features in horses with dental disease and sinusitis. The first molar was the most frequently affected maxillary cheek tooth. Hypoattenuation of the cementum, destruction of the enamel, and filling of the infundibular cavity with gas were the most frequent CT findings associated with caries. Gas bubbles within the bulging root area or fragmentation of the root in combination with swelling of the adjacent sinus lining were the most important CT features of dental decay. CT findings associated with sinusitis included excessive thickening of the respiratory epithelium in the rostral maxillary sinus; the caudal maxillary sinus was less often involved. The infraorbital canal, the nasomaxillary duct, and the frontomaxillary aperture were usually involved. The maxillary bone, however, especially the facial crest, was involved in nearly every horse, being characterized by endosteal sclerosis, thickening, periosteal reaction, and deformation leading to facial swelling in chronic infections. CT images allowed identification of involvement of individual teeth more clearly to reveal the diseased one for treatment. Three-dimensional imaging allowed improved understanding of the extent and severity of the pathologic change.     

Radiotherapy of a recurrent ossifying fibroma in the paranasal sinuses of a horse

A 7-year-old female Thoroughbred was admitted with a history of labored breathing, stridor, and exercise intolerance. Examination revealed a mass in the left paranasal sinuses that was determined to be an ossifying fibroma. Initial treatment consisted of surgical removal of the mass alone; however, the mass recurred 9 months after surgery. The mass was again removed, and adjunctive radiotherapy consisting of 3,000 cGy of cobalt radiation was administered. This time, the tumor did not recur for > 6 years. A third surgery was performed to remove the mass, and adjunctive radiotherapy consisting of 4,000 cGy of photon beam radiation from a linear accelerator was administered. The mass did not recur during the subsequent 3 years. Ossifying fibromas are uncommon tumors that frequently recur if incompletely excised. Results in this horse suggest that adjunctive radiotherapy may delay or prevent tumor recurrence in affected horses.     

Radiographic differentiation of mediastinal versus pulmonary masses in dogs and cats can be challenging

The ability to differentiate thoracic masses of mediastinal and pulmonary origins is often confounded by their complex spatial relationship. The objectives of this retrospective, observational cross‐sectional study were to assess radiographic differentiation of mediastinal versus pulmonary masses, and to determine if there are any correlations with specific radiographic findings. Thoracic radiographs of 75 dogs and cats with mediastinal and/or pulmonary masses identified on CT were reviewed. Radiographic studies were anonymized, randomized, and reviewed twice by three reviewers. Reviewers categorized the origin of each mass(es) as mediastinal, pulmonary, or both. On the second review, the presence or absence of 21 different radiographic findings was recorded for each mass. Agreement between the radiographic and CT categorization of mass origin, as well as inter‐ and intraobserver agreement, was calculated. Overall agreement between radiographs and CT was moderate for both mediastinal (68.6%) and pulmonary masses (63%). Overall, interobserver agreement was moderate (κ = 0.50‐0.74), with moderate to strong intraobserver agreement (κ = 0.58‐0.93). Masses within the mediastinum were significantly more likely to displace other mediastinal structures. Alternatively, masses lateral to midline and in the caudal thorax were found to be significantly positively correlated with a pulmonary origin. The results of this study highlight the limitations of radiography for differentiation of mediastinal and pulmonary masses, with mass location and displacement of other mediastinal structures potentially useful for radiographic findings that may help improve accuracy.     

Histopathological Characteristics of an Ossifying Fibroma Formed in the Maxilla of a Racehorse

A 1-year-old male thoroughbred racehorse experienced swelling of the left upper lip. The swelling was attributable to enlargement around the incisive bone of the interdental space posterior to the third incisor in the left maxilla. Even after two operations to reduce the bulk of the mass, it continued to increase in size. Dyspnea caused by stenosis of the nasal cavity forced us to perform euthanasia, and a pathological examination was conducted. Macroscopic examination of a section of the mass revealed the formation of multiple areas of solid fibrous tissue, and trabeculae within the incisive bone which had displaced the cortical bone. On histology, the mass was composed of trabecular bone-like structures due to the proliferation and aggregation of fibroblasts. Therefore, we diagnosed it as an ossifying fibroma. Equine ossifying fibroma is characterized by development in the mandible, but was formed in the maxilla in this case. Equine ossifying fibroma has not been reported previously in Japan. This is the first case of equine ossifying fibroma identified in Japan.     

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF ODONTOGENIC NEOPLASMS IN DOGS

Odontogenic neoplasms are locally invasive oral tumors in dogs. The purpose of this retrospective study was to describe CT characteristics for varying histopathologic types of canine odontogenic neoplasms. A board‐certified veterinary radiologist who was unaware of histologic findings reviewed and scored imaging studies. A total of 29 dogs were included in the study. Twenty‐three of these dogs had concurrent dental radiographs. The most common CT characteristics for all tumor types were a direct association with or in the region of multiple teeth in 96.4% (27/28), contrast enhancement in 96.3% (26/27), alveolar bone lysis in 93.1% (27/29), and mass‐associated tooth displacement in 85.2% (23/27). Mass‐associated cyst‐like structures were identified in 53.6% (15/28) and were only present in tumors containing odontogenic epithelium. Canine acanthomatous ameloblastomas (n = 15) appeared as extra‐osseous (10/15) or intra‐osseous (5/15) masses. Intra‐osseous canine acanthomatous ameloblastomas were more likely to have mass‐associated cyst‐like structures and were subjectively more aggressive when compared with extra‐osseous canine acanthomatous ameloblastomas. Amyloid‐producing odontogenic tumors (n = 3) had subjectively uniform CT imaging characteristics and consisted of round soft tissue and mineral attenuating masses with multiple associated cyst‐like structures. Fibromatous epulides of periodontal ligament origin (n = 4) were contrast enhancing extra‐osseous masses that were rarely referred for CT examinations and 25% (1/4) were not visible with CT. Other odontogenic tumors were less represented or had more variable CT imaging characteristics. Mass‐associated tooth destruction was appreciated more often with dental radiographs and extra‐oral tumor extension was identified more often with CT.     

Use of a carbon dioxide laser for surgical management of cutaneous masses in horses: 32 cases (1993-2000)

OBJECTIVE: To determine outcome of horses in which cutaneous masses were removed with a carbon dioxide laser. DESIGN: Retrospective study. ANIMALS: 32 horses. PROCEDURE: Medical records of horses with 1 or more cutaneous masses treated with a carbon dioxide laser were examined. Follow-up information was obtained through telephone interviews with owners and referring veterinarians. RESULTS: Cutaneous masses were classified as sarcoids (15 horses), neoplastic masses other than sarcoids (squamous cell carcinoma [91; fibroma [1]; and melanoma [1]), and nonneoplastic masses (6). Minimum follow-up time was 6 months. Five sarcoids and 2 squamous cell carcinomas recurred. Seven (21%) horses had complications associated with dehiscence of wounds that had been closed primarily or failure of wound healing because of recurrence of the mass. Twenty-six (81%) owners were satisfied with the cosmetic appearance following surgery. CONCLUSION AND CLINICAL RELEVANCE: Results suggest that a carbon dioxide laser may be effective for treatment of cutaneous masses in horses.     

The role of head computed tomography in equine practice

This retrospective study describes the computed tomography (CT) findings in 59 horses presented with diseases of the head over 8 years that underwent CT examination of this region, including dental or sinonasal diseases (Group A) (n = 42), osseous and/or articular diseases (Group B) (n = 11) and soft tissue diseases (Group C) (n = 6). For Group A, radiographic and CT findings comparison was possible. Computed tomography had higher sensitivity (100%) and specificity (96.7%) than radiography in diagnosing dental disease. Compared to CT, radiographic identification of sinus involvement was less sensitive, particularly for ventral conchal and sphenopalatine sinuses and presented an overall sensitivity of 43.5 and 16.7%, respectively. In Group B CT allowed identification of a higher number of bone fragments and fractures in the maxillary, lacrimal, sphenoidal, temporal and zygomatic bones not identified radiographically. Accurate identification of CT changes in the temporomandibular joint and temporohyoid articulation was also possible. Group C included both intra‐ and extra‐cranial disease, retrobulbar masses being the most representative pathology (n = 3). In this group, CT was considered the gold standard for detection of periorbital diseases. We conclude that CT is an imaging technique with high diagnostic value for evaluating the equine head, yielding additional information over multiple radiographic views, which may alter the outcome of the case. Additionally, this paper reports several conditions not previously described using CT.     

Association of magnetic resonance imaging findings and histologic diagnosis in dogs with nasal disease: 78 cases (2001-2004)

OBJECTIVE-To determine whether magnetic resonance imaging (MRI) features correlated with histologic diagnosis in dogs with nasal disease. DESIGN-Retrospective case series. ANIMALS-78 Dogs undergoing MRI for evaluation of nasal disease. PROCEDURES-Medical records and MRI reports of dogs were reviewed to identify MRI features associated with histologic diagnosis. Features evaluated were presence of a mass effect, frontal sinus involvement, sphenoid sinus involvement, maxillary recess involvement, nasopharyngeal infiltration by soft tissue, nasal turbinate destruction, vomer bone lysis, paranasal bone destruction, cribriform plate erosion, and lesion extent (ie, unilateral vs bilateral). RESULTS-33 Dogs had neoplastic disease, 38 had inflammatory rhinitis, and 7 had fungal rhinitis. Lesion extent was not significantly associated with histologic diagnosis. Absence of a mass effect was significantly associated with inflammatory disease. However, presence of a mass was not specific for neoplasia. In dogs with evidence of a mass on magnetic resonance (MR) images, nasal turbinate destruction, frontal sinus invasion, and maxillary recess invasion were not useful in distinguishing neoplastic from nonneoplastic disease, but cribriform plate erosion, vomer bone lysis, paranasal bone destruction, sphenoid sinus invasion, and nasopharyngeal invasion were. CONCLUSIONS AND CLINICAL RELEVANCE-Results suggested that in dogs with nasal disease, the lack of a mass effect on MR images was significantly associated with inflammatory disease. In dogs with a mass effect on MR images, vomer bone lysis, cribriform plate erosion, paranasal bone destruction, sphenoid sinus invasion by a mass, and nasopharyngeal invasion by a mass were significantly associated with a diagnosis of neoplasia.     

Equine juvenile mandibular ossifying fibroma

Benign proliferative fibro-osseous lesions of the rostral mandible in six young horses are classified as equine juvenile mandibular ossifying fibroma. Histologically there is a characteristic abrupt transition from subgingival fibroblastic stroma to a zone of proliferating osteoblasts that form irregular spicules of osteoid. The layer of proliferating osteoblasts blends with a deeper zone of bony trabeculae rimmed by osteoblasts and separated by intertrabecular spaces of moderate cellular density. Incomplete surgical excision resulted in local recurrence, while rostral mandibulectomies resulted in no recurrence. The predilection for the rostral mandible of young horses coupled with the similar clinical, radiographic, and histological characteristics supports the classification of this lesion as a distinct entity.