Combined surgical and radiotherapy treatment of a mandibular ameloblastic carcinoma in a pony

A 9‐year‐old Welsh Section D gelding was referred to an equine hospital for evaluation and computed tomographic (CT) imaging of a left mandibular swelling. An expansile mass, found within the left mandible at the level of the caudal 2 cheek teeth, was surgically debulked and histology of the lesion identified it as an ameloblastic carcinoma. Radiotherapy using 4 fractions of 800 cGy, 7 days apart, was subsequently undertaken. The pony made excellent clinical progression following treatment. Repeat CT imaging at 7.5 and 19.5 months post surgery showed no apparent recurrence of the lesion and marked improvement in the remodelling of the mandible. In conclusion, radiotherapy in conjunction with surgical debulking appears to have been successful in treating an ameloblastic carcinoma in this pony and could be considered for similar tumours in other cases.     

Surgical management of ameloblastic fibroma in the cat

A 14-month-old spayed female domestic short-haired cat was presented for evaluation of a rostral mandibular mass diagnosed from biopsy as an ameloblastic fibroma. Radiographs of the mandible demonstrated marked osteolysis and cortical expansion. A rostral mandibulectomy was performed extending from the caudal edge of the second premolar on the right side to the caudal edge of the canine tooth on the left side. Histological evaluation of the excised mass confirmed the diagnosis of ameloblastic fibroma. Follow-up evaluation at eight months revealed normal oral function with the exception of occasional saliva soiling of the chin. The owner was satisfied with the cosmetic result.     

Oncocytoma in the mandibular salivary gland of a cat

A cat was referred for investigation of a soft tissue mass caudal to the left mandible. Initial investigations suggested a malignant salivary gland tumour, and the mass was removed by extracapsular resection of the mandibular gland. Histopathology showed an oncocytoma within the salivary gland. An oncocytoma is a neoplastic transformation of oncocytes. Oncocytes are cells with a small nucleus and intense eosinophilic granular cytoplasm due to numerous mitochondria, which proliferate during ageing in exocrine and endocrine glandular tissues. Physiological proliferation occurs next to oncocytosis, oncocytoma, and oncocytic carcinoma. This is the first report of an oncocytoma in a feline mandibular salivary gland, and the first report of long-term survival after surgical removal.     

Ameloblastic odontoma in the mandible of a llama

A 4-year-old llama had an aggressive, multiloculated, expansile bone lesion involving the rostral mandible. The mandibular lesion was imaged using radiography and computed tomography. Antemortem diagnosis of an ossifying fibroma was made histologically. Postmortem findings showed the lesion to be limited to the mandible. Final diagnosis was ameloblastic odontoma.     

Mast cell tumor in the mandibular salivary gland in a dog

A mast cell tumor in the mandibular salivary gland was diagnosed in a 9-year-old English Setter. Dense infiltrating sheets of mast cells were present within the mandibular salivary gland, the medial retropharyngeal lymph node and in two subcutaneous masses on the flank. The salivary gland, lymph node, and masses were excised. The dog was treated postoperatively with the histamine receptor antagonist, cimetidine and the alkylating agent, chlorambucil. The tumor recurred at the angle of the mandible 4 months later and the dog was killed.     

Treatment of mandibular squamous cell carcinoma in cats by use of mandibulectomy and radiotherapy: seven cases (1987-1989).

Seven cats with squamous cell carcinoma involving the mandible were treated by surgery and radiotherapy. Surgery consisted of hemimandibulectomy or combined rostral and hemimandibulectomy, gastrostomy tube placement, and submandibular lymph node excisional biopsy. Radiotherapy (orthovoltage or 60Co) commenced 2 weeks after surgery. Histologically, the tumor invaded surgical margins in 6 of 7 cats. Nerve infiltration was histologically identified in 2 cats. All cats had stage-3 disease with radiographic evidence of mandibular bone involvement. Age ranged between 8 and 16 years (median, 10 years). Hypercalcemia (2), feline immunodeficiency virus (2), and hyperthyroidism (1), were detected in cats prior to treatment. Survival after surgery was a median of 14 months (range = 3 to 36 months, mean = 15 months). Six cats were euthanatized because of recurrence of disease at 3, 7, 9, 16, 21, and 36 months. One cat was euthanatized at 14 months because of an unrelated disease. Complications of tongue lagging, drooling after meals, mandibular drift, maxillary ulceration, and alopecia of the jaw developed in a few cats. Radiation at the primary site and regional lymph nodes after surgery of curative intent extended survival in cats with mandibular squamous cell carcinoma.     

Odontoma in a juvenile boxer: Clinical, radiographic and pathological findings

Compound odontoma was diagnosed in a seven-month-old boxer dog. The hamartoma presented as an expansile painless mass in the right rostral hemimandible, causing severe distortion of the incisor arcade. Radiographs revealed filling of the medullary cavity of the bone by soft tissue containing mineralised foci, with attendant cortical thinning. The lesion was excised. Histological evaluation demonstrated a connective tissue stroma containing multiple irregular foci of enamel and dentine resembling rudimentary teeth (denticles). These were typically bounded by an ameloblastic zone and contained a central area of odontoblasts and dental pulp. At nine months after surgery, no recurrence has been recognised.     

Malignant nonteratoid ocular medulloepithelioma in a llama (Llama glama).

A 6-year-old female llama presented with buphthalmos of its right eye owing to the presence of an intraocular mass. The affected globe was enucleated and submitted for microscopic examination. The intraocular mass was diagnosed as malignant medulloepithelioma. Within the following months, the llama developed soft tissue masses, which completely filled the right orbital cavity and expanded the cranial portion of the right mandibular bone, and enlarged mandibular lymph nodes. Euthanasia was elected 30 months after the initial diagnosis. The carcass was submitted for postmortem examination, which revealed the presence of medulloepithelioma metastases within the right orbit, mandible, mandibular lymph nodes, lungs, liver, and mesenteric and sublumbar lymph nodes. The primary intraocular tumor and its metastases were composed of neoplastic undifferentiated neuroepithelial cells, which formed tubules, Flexner-Wintersteiner and Homer Wright rosettes, and rare solid sheets. Electron microscopy showed that tumor cells were connected by desmosome-like junctions and contained rare intracytoplasmic basal bodies. Neoplastic cells were positive for vimentin, nestin, microtubule-associated protein 1B, S-100 protein, and glial fibrillary acidic protein (GFAP). To the best of the authors' knowledge, this is the first report of a malignant nonteratoid ocular medulloepithelioma with distant metastases in a llama and of the ultrastructural and extended immunohistochemical characterization of a nonteratoid medulloepithelioma in this species.     

Fibromatous epulis in a Campolina horse

An 11-year-old Campolina horse was referred to the Veterinary Hospital due to the presence of an exophytic mass located in the rostral region of the mandible. Radiographic evaluation showed no evidence of tumour infiltration in the underlying mandibular bone, and the histopathology and immunohistochemical evaluations confirmed the diagnosis of fibromatous epulis. The treatment included surgical excision of the mass, followed by extensive curettage of the underlying mandibular bone. Complete healing of the wound was evidenced 60 days after the procedure; however, relapse was reported by the owner between 1 and 3 years after surgery.     

Multilobular tumor of bone in the mandible of a dog

An 8-year-old Siberian husky dog was presented for a mass involving the rostral mandible. Intraoral radiographs demonstrated diffusely irregular bone and displacement of all mandibular incisor teeth. The mass was diagnosed as a grade I multilobular tumor of bone based on incisional biopsy. A bilateral rostral mandibulectomy was performed with tumor negative margins. Oral examination at 14-months following surgery indicated normal healing with minimal side effects and no evidence of tumor recurrence.     

Intracranial,extraneural ectopic lymph node in a bovine (Bos taurus)

The brain from a field necropsied 8‐month‐old feedlot heifer presenting with an acute history of depression, lethargy, dyspnoea and anorexia was evaluated grossly and by histopathology. The meninges overlying the left cerebral hemisphere contained a 12 × 26 × 32 mm, dark red, soft, ovoid mass. Histologic examination of this tissue revealed a well‐organized lymph node with normal architecture. Organization of reactive lymphoid tissue resembling normal lymph node architecture may occur under chronic stimulation. However, there are no known aggregates of lymphoid tissue present within the cranial vault in any veterinary species. This is the first reported case of an intracranial ectopic lymph node in any species.     

Indirect magnetic resonance lymphography of the head and neck of dogs using Gadofluorine M and a conventional gadolinium contrast agent: A pilot study

The purpose of this pilot study was to evaluate lymph node enhancement with an indirect magnetic resonance (MR) lymphography technique using 2 different contrast agents in the head and neck region of healthy dogs. Five dogs were imaged at various times after intradermal injection of gadoversetamide and Gadofluorine M (minimum of 1 week apart) in the right and left mandibular, temporal, and lateral neck regions. We observed consistent progressive enhancement with time in the mandibular, retropharyngeal, and superficial cervical lymph nodes. The node enhancement was comparable for both contrast agents. Contrast enhancement of the parotid lymph nodes was not seen. We conclude that this technique of indirect MR lymphography using either agent could be used to identify those lymph nodes at highest risk of metastatic disease in dogs with cancer, and to guide staging and treatment.     

Mandibular fracture repair in a harbor seal

A 30-year-old captive female harbor seal (Phoca vitulina) bit down upon a metal ring within a hoop-net normally used to assist in securing the seal for routine physical examination. Radiographic examination performed under general anesthesia revealed a unilateral closed fracture of the rostral left mandible between the first and second premolar teeth. The rostral fragment was displaced ventrally and slight laxity of the mandibular symphysis was noted. The fracture was repaired surgically using an oral dental acrylic splint incorporating circumferential mandibular cerclage wire. The mandibular symphysis was stabilized using interdental wire between the right and left canine teeth. The fixation device was removed following evaluation of radiographs that showed signs of bony union 12-months postoperatively.     

Influence of an interdental full pin on stability of an acrylic external fixator for rostral mandibular fractures in dogs

OBJECTIVE: To determine total stiffness and gap stiffness of an external fixation system in a canine mandibular fracture gap model incorporating a full interdental pin as the only point of rostral fixation in a bilateral type-I external fixator. SAMPLE POPULATION: 10 canine mandibles. PROCEDURE: Bilateral mandibular ostectomies were performed between premolars 3 and 4. A type-I external fixator incorporating a full interdental pin was placed to stabilize a 0.5-cm fracture gap. Four pin configurations (intact mandibular bodies with fixator; ostectomized mandibular bodies and complete fixator; ostectomized mandibular bodies with caudal pins of rostral fragment cut; ostectomized mandibular bodies with all pins of rostral fragment cut) were tested in dorsoventral bending 5 times on each mandible. The full interdental pin remained intact in all configurations. Total stiffness and gap stiffness were determined for each configuration on a materials testing machine. RESULTS: Total stiffness of intact mandibles was significantly greater than that of ostectomized mandibles, regardless of external fixator configuration. However, total stiffness and gap stiffness were not significantly different among different external fixator configurations applied to ostectomized mandibles. CONCLUSION AND CLINICAL RELEVANCE: External fixator configurations with only the full interdental pin engaging the rostral fragment were as stiff as configurations that had 2 or 4 additional pins in the rostral fragment for the applied loads. External fixators for rostral mandibular fractures may be rigidly secured with rostral fragment implants applied extracortically, avoiding iatrogenic trauma to teeth and tooth roots.     

Radiographic and computed tomographic appearance of caseous lymphadenitis in a goat

A 2‐year‐old Boer doe was presented with respiratory distress and severe inspiratory dyspnea. Cervical and thoracic radiographs revealed a marked retropharyngeal soft tissue mass effect, several mineralized pharyngeal and retropharyngeal structures, and a pulmonary mass. Computed tomography (CT) revealed a severely enlarged right medial retropharyngeal lymph node, which caused laryngeal compression, leading to upper airway obstruction. Multiple cervical and thoracic lymph nodes, and the pulmonary mass had an irregular layered/laminated pattern of mineralization. Imaging findings were consistent with caseous lymphadenitis, and further confirmed with culture, necropsy, and histopathology. This is the first report of CT appearance of caseous lymphadenitis in a goat.     

Thyroid follicular adenocarcinoma in a ferret

A 5-year-old male castrated ferret was presented to the Washington State University College of Veterinary Medicine for evaluation of progressive hair loss and a large, rapidly growing ventral neck mass. The patient had been diagnosed previously with an insulinoma, which was managed medically. Fine-needle aspirates of the neck mass were performed. The cytologic results were most consistent with epithelial neoplasia, likely a carcinoma; thyroid origin was considered likely based on tumor location and cell morphology. The tumor grew rapidly, and the owners elected euthanasia 1 week after examination. At necropsy, a circumscribed, ovoid mass disrupted the right cervical musculature next to the right lobe of the thyroid gland. Histopathologic evaluation revealed an infiltrative mass consisting of cuboidal cells arranged in solid sheets and irregular follicles enclosing colloid. The cells were large, with prominent nucleoli, and had a high mitotic rate. The histopathologic diagnosis was consistent with thyroid follicular adenocarcinoma. Immunochemical findings confirmed thyroglobulin production by neoplastic cells, but to a lesser extent than in normal ferret thyroid tissue. To our knowledge, this is the first case of thyroid follicular adenocarcinoma to be reported in a ferret, with only 1 other case of thyroid carcinoma, a C-cell carcinoma, described previously.     

Lymph node staging of oral and maxillofacial neoplasms in 31 dogs and cats

A retrospective study was performed to report the histologic examination results of regional lymph nodes of dogs and cats with oral or maxillofacial neoplasms. Twenty-eight dogs and 3 cats were evaluated. Histologic examination results of standard and serial tissue sectioning of regional lymph nodes were recorded. When available, other clinical parameters including mandibular lymph node palpation, thoracic radiographs, and pre- and postoperative fine needle aspiration of lymph nodes were compared with the histologic results. Squamous cell carcinoma, fibrosarcoma, and melanoma were the most common neoplasms diagnosed in dogs. Squamous cell carcinoma and fibrosarcoma were diagnosed in cats. Of the palpably enlarged mandibular lymph nodes, 17.0% had metastatic disease histologically. Radiographically evident thoracic metastatic disease was present in 7.4% of cases. Preoperative cytologic evaluation of the mandibular lymph node based on fine needle aspiration concurred with the histologic results in 90.5% of lymph nodes examined. Postoperative cytologic evaluation of fine needle aspirates of regional lymph nodes concurred with the histologic results in 80.6% of lymph nodes examined. Only 54.5% of cases with metastatic disease to regional lymph nodes had metastasis that included the mandibular lymph node. Serial lymph node sectioning provided additional information or metastasis detection. Cytologic evaluation of the mandibular lymph node correlates positively with histology, however results may fail to indicate the presence of regional metastasis. Assessment of all regional lymph nodes in dogs and cats with oral or maxillofacial neoplasms will detect more metastatic disease than assessing the mandibular lymph node only.     

Use of serial standing computed tomography for diagnosis,treatment and monitoring of a horse with acute myonecrosis of the head

An 11-year-old American Quarter Horse gelding was referred to the JT Vaughan Large Animal Teaching Hospital at Auburn University, College of Veterinary Medicine, for investigation of acute and severe right-sided facial swelling and nasal discharge. Standing computed tomographic (CT) examination of the head identified severe soft tissue swelling surrounding the right mandible, emphysema within the soft tissues tracking along fascial planes and right-sided caudal and rostral maxillary sinusitis. Using CT identification and ultrasound guidance, several targeted fasciotomies were created into the right masseter, cranial cervical musculature, supraorbital space and caudo-medial aspect of the mandible. The right-sided sinusitis was treated by right conchofrontal sinus trephination and lavage. Aerobic and anaerobic cultures obtained from the fasciotomy sites and conchofrontal sinus both yielded Prevotella intermedia and Peptostreptococcus asaccharolyticus. During hospitalisation, serial, standing CT examinations were performed for monitoring case progression and guiding further fasciotomies in the face of continued myonecrosis. Follow-up CT performed at 1 month showed resolution of the emphysema and presence of chronic right ventral conchal sinusitis. The sinusitis was treated by fenestration of the right ventral concha with a diode laser via the nasal passage.     

Rostral Mandibulectomy Three Case Reports in Dogs

A rostral mandibulectomy was performed on three dogs with mandibular neopiasia. The technique involves stabilization of the mandibular rami, excision of the mandible rostral to the frenulum of the tongue, and cosmetic closure of the wound. Two patients were living 11 months postoperatively. This technique is effective in treating some malignant neoplasms of the rostral mandible.