Multilobular tumour of the caudal cranium causing severe cerebral and cerebellar compression in a dog

Multilobular tumour of bone (MTB) is an uncommon tumour and is usually located in the skull. A 13-year-old mixed breed dog was presented with a two-week history of progressively worsening vestibular dysfunction and cognitive abnormalities; it appeared demented and showed asymmetric ataxia and hypermetria of all limbs. The owner opted to have the animal euthanised. Necropsy revealed a large mass occupying the right occipital, parietal and temporal bones, severely compressing the cerebellum and the right occipital lobe. Histologically, it was characterised by the presence of multiple lobules containing osteoid or cartilage and separated by fibrous septae, features typical of MTB. Lung metastases were evident. To our knowledge, this is the first report of an MTB causing both severe cerebral and cerebellar compression and the second detailed report of an MTB of the occipital bone. MTB should be included in the differential diagnosis of bone tumours as well as in cases with central vestibular disease.     

Intracranial botryomycosis in a mature horse

This case report describes an unusual diagnosis of central nervous system botryomycosis in a horse. A 16‐year‐old Welsh Section D gelding was evaluated for acute onset of hypermetric ataxia, leaning to the left and head tilt to the right. Based on the neurological signs, a cerebellar lesion with accompanying vestibular disease was suspected and supportive therapy consisting of antimicrobial and glucocorticosteroid drugs and hypertonic saline was instituted. This resulted in marked clinical improvement over a 48 h period. Computed tomography performed in the standing, sedated horse following initial stabilisation identified extensive sclerosis and lysis of the right temporal and occipital bones, consistent with an infectious or neoplastic process. Based on the grave prognosis for survival despite the clinical improvement, euthanasia was undertaken. Post mortem magnetic resonance imaging identified a mass lesion impinging on the right cerebellar hemisphere, sclerosis of the temporal and occipital bones lateral and ventral to the mass, as well as destruction of the temporal bone between the inner ear and the cerebellum. These changes corresponded to the presence of a mass within the right dorsal temporal bone, extending into the right lateral temporal bone. The mass extended to compress and adhere to the right lateral hemisphere of the cerebellum. A histopathological diagnosis of botryomycosis was made, affecting the temporal and occipital bones and compressing the cerebellum.     

Intracranial abscess caused by Rhodococcus equi infection in a foal

CASE DESCRIPTION: A 4-month-old Missouri Fox Trotter colt was examined for a 5-week history of head tilt after treatment for suspected pulmonary Rhodococcus equi infection. CLINICAL FINDINGS: Computed tomography revealed osteolysis of the occipital, temporal, and caudal portion of the parietal bones of the left side of the cranium. A soft tissue mass compressing the occipital region of the cerebral cortex and cerebellum was associated with the osteolytic bone. TREATMENT AND OUTCOME: A rostrotentorial-suboccipital craniectomy approach was performed to remove fragmented occipital bone, debulk the intracranial mass, and obtain tissue samples for histologic examination and bacterial culture. All neurologic deficits improved substantially within 3 days after surgery. Bacterial culture of the resected soft tissue and bone fragments yielded R equi. CLINICAL RELEVANCE: Intracranial surgery in veterinary medicine has been limited to dogs and cats; however, in select cases, extrapolation of surgical techniques used in humans and small animals can assist with intracranial procedures in horses.     

Use of a titanium mesh for cranioplasty following radical rostrotentorial craniectomy to remove an ossifying fibroma in a dog

CASE DESCRIPTION: A 6-year-old Australian Terrier was evaluated for surgical removal of an ossifying fibroma of the left calvarium of 7 months' duration. CLINICAL FINDINGS: Computed tomography revealed invasion of the mass through the left parietal bone and extension into the epidural space of the brain. TREATMENT AND OUTCOME: A left rostrotentorial and frontal bone craniectomy was performed, and the mass was removed, along with a 1-cm margin of grossly normal bone. Cranioplasty was performed with a combination of porcine submucosa, titanium mesh, and screws. The dog recovered from surgery without complications and was discharged 3 days later. The dog was followed up for 24 months after surgery and has remained clinically normal. CLINICAL RELEVANCE: Findings suggested that rostrotentorial craniectomy is a viable option for removal of benign tumors affecting the parietal bones in dogs. Reconstruction of the resulting defect in the calvarium is possible with a combination of porcine submucosa and rigid titanium mesh.     

Primary osteosarcoma of the synovium in a dog

An eight-year-old, spayed female Labrador retriever was presented for evaluation of left thoracic limb lameness. Radiographs of the left elbow revealed mineralization of the soft tissues surrounding the joint, with no evidence of periarticular bony lysis. Biopsy of the synovial tissues of the left radiohumeral joint yielded a diagnosis of osteosarcoma (OSA). The dog was treated with palliative radiotherapy, piroxicam, and carboplatin chemotherapy, which resulted in excellent pain control for approximately eight months. Amputation of the affected limb was then performed. Six months later, the dog developed multiple subcutaneous OSA metastases, and the dog was euthanized 15 months after diagnosis due to refractory vomiting. This report documents the first known case of primary OSA of the synovium in any species.     

Osteosarcoma in adjacent lumbar vertebrae in a dog

An 8-year-old male Belgian Malinois was referred for evaluation of progressive caudal paresis of 2 to 3 weeks' duration. Radiography revealed a mottled appearance to the body of L4 and misshapen intervertebral foramen at L4-L5. Myelography revealed that the dye column terminated within the body of L4. Computed tomography revealed a soft tissue mass adjacent to or involving the spinal cord and L4, with complete destruction of a portion of the floor of the vertebral foramen. Small circular lesions were also noticed within the body of L3 and L5. A left-sided hemilaminectomy was performed. Histologic examination of a biopsy specimen revealed a high-grade sarcoma. Because of the poor prognosis, the dog was euthanatized. Necropsy examination revealed osteosarcoma, with lesions in L3 to L7, the sacrum, and the lungs. Metastatic lesions in adjacent bones have been termed skip metastases and the primary tumor is typically in long bones. Prognosis associated with skip metastases is similar to or even graver than that associated with pulmonary metastases. In the dog of the present report, the unusual finding of distinct foci of osteosarcoma within 5 adjacent lumbar vertebrae and the sacrum was consistent with skip metastases, potentially spread via the vertebral venous plexus.     

A Macro‐Anatomical Investigation of the Some Skull Bones of Nehring's Blind Mole Rats (Spalacidae: Nannospalax nehringi)

This study was aimed to demonstrate the specific anatomical features of the skull bones of Nehring's blind mole rats. Eight skulls, belonging to animals of both sexes, were used. The occipital squama contributed to the formation of the caudal portion of the skull roof. The foramen magnum was quite large. The external occipital crest was present only in the males. The parietal bones formed the middle portion of the skull roof together with the well‐developed inter‐parietal bones. The zygomatic process of the temporal bone formed the zygomatic arch by extending to the temporal process of the zygomatic bone. The zygomatic process of the frontal bone and the frontal process of the zygomatic bone laterally bordered the orbit. There was a single septal process of the nasal bone. Each ramus of the mandibula had four processes. The mandibular ramus had an angular process on its caudal rim, which extended dorsolaterally. The dorsal free end of the mandibular ramus possessed a coronoid process. In the back, there were two other processes, situated medially and laterally. The medially situated process was referred to as a condylar process, and the laterally situated process was referred to as an alveolar process. The alveolar process detected on the mandibular ramus has not been reported in any rodent species, other than those of the family Spalacidae. Blind mole rats can be a real eye‐opener for evolutionary science. The burrowing rodents are key to answering a controversial question about how new species arise.     

Osteosarcoma with multiple metastases and subcutaneous involvement in a rabbit (Oryctolagus cuniculus)

BACKGROUND: Osteogenic sarcomas are rare in rabbits, but cases involving the mandible, ribs, frontal bones, and tibia have been reported. OBJECTIVE: The purpose of this study was to describe the clinical and pathologic findings in a rabbit with osteosarcoma and multiple metastases with subcutaneous involvement. METHODS: A 1-year-old female Polish rabbit was evaluated for dysorexia, lameness, gait difficulties with the hind limbs, and the presence of 2 subcutaneous nodules, on the left thigh and in the dorsal region. A hard swelling was also present at the base of the tail. Radiographic findings revealed multiple abnormalities in several bones, which were more severe in the sacrococcygeal region and femur. Several areas of calcification involving the thorax and abdomen as well as skeletal muscles, also were noted. The thigh nodule was surgically removed, and cytologic and histologic evaluations were performed. Following the rabbit's death, postmortem radiographs were taken and necropsy was performed. Samples of tissues and organs, involved bone segments, and other subcutaneous nodules were collected and examined by cytology and histology. RESULTS: Both the subcutaneous nodules and the majority of tissues and organs contained neoplastic cells whose appearance was consistent with osteogenic sarcoma. CONCLUSION: Clinical, radiologic, and pathologic data supported a diagnosis of osteosarcoma with multiple metastases and subcutaneous involvement.     

Infiltrative lipoma in cervical bones in a dog

A 4-year-old, neutered male Maltese presented with a 2-month history of right hemiparesis. The radiographic findings revealed bone lysis, and sclerotic changes in the right section of the fifth and sixth cervical bones with a mild radiolucent mass around the lesion. The magnetic resonance imaging revealed a hyperintense mass located in the region extending from the muscles to the bones and compressing the spinal cord. The mass was removed via a hemilaminectomy in the cervical area using the ventral and dorsal approach, and a histological examination confirmed that it was adipose tissue. An infiltrative lipoma was diagnosed based on these findings. The dog has ambulated normally for 24 months since undergoing surgery.     

Diagnosis and treatment of a cerebral infarct in a chimpanzee (Pan troglodytes).

A 29-yr-old chimpanzee (Pan troglodytes) presented after an acute onset of right facial and forearm paresis that progressed to paralysis within 24 hr, with subsequent development of right leg paresis. Magnetic resonance imaging (MRI) of the head revealed an abnormal region of increased signal intensity in the left frontal, parietal, and temporal cerebral hemispheres, corresponding to the vascular territory of the middle cerebral artery, with resultant compression of the left lateral ventricle. The findings were consistent with a cerebral infarct (stroke). MRI is the most sensitive test for early detection of cerebral changes due to ischemia and was essential in obtaining a diagnosis in this case. The chimpanzee responded well to treatment with long-term anticoagulant aspirin and a short, tapered course of prednisone and regained full gross motor function.     

Metastatic Tumor in Pregnancy: Placental Germ Cell Tumor With Metastasis to the Foal

A placental mass was observed in an otherwise-healthy Quarter Horse mare; subsequently, the mare's 52-day-old foal was examined because of hind limb ataxia, urinary incontinence, and raised lesions of the distal limbs. Clinical and biochemical findings were supportive of liver disease and lumbosacral injury. Ultrasonographic evaluation of the abdomen suggested a liver mass, which was confirmed with computed tomography (CT) and determined to be neoplastic via histopathologic evaluation of a liver biopsy sample. Initial histopathology suggested a germ cell tumor. Regions of lysis affecting both femurs and third metacarpal bones and a complete oblique sagittal fracture through the body of the first sacral vertebra were present on CT. Supportive care was provided until CT confirmation of diffuse hepatic neoplasia and vertebral fracture. Necropsy revealed a large multinodular mass within the liver and a pathologic fracture of the first sacral vertebral body. Histopathologic comparison between neoplastic cells examined from the placenta and foal confirmed metastases of a germ cell tumor. Placental tumors are rare in all species; however, when noted in horses, clinicians should be aware of the possibility of metastatic spread to the foal.     

Squamous cell carcinoma causing blindness and ophthalmoplegia in a cat

Ophthalmoplegia and blindness caused by squamous cell carcinoma were reported in a cat. Unilateral functional deficits of cranial nerves II, III, IV, and VI and of the sympathetic nerve supply caused blindness, complete ophthalmoplegia, and Horner syndrome. Radiography and computed tomography revealed a proliferating bony lesion associated with the right tympanic bulla, right temporal bone, right side of the mandible, and left frontal bone. A focal area of bony destruction involved the right sphenoid bone. The cat was euthanatized and necropsied. Squamous cell carcinoma was identified invading the bones and rostral part of the right side of the skull. The tumor had extended through the sphenoid bones into the region of the cavernous sinus and had surrounded the cranial nerves passing through this region. It also had invested connective tissue surrounding the optic nerves and had invaded the right globe through the lamina cribrosa. This represents an unusual distribution for ocular cranial squamous cell carcinoma in a cat.     

Scedosporium prolificans infection associated with arthritis and osteomyelitis in a horse

Scedosporium prolificans was associated with arthritis and degenerative osteomyelitis in a 6-year-old Thoroughbred racehorse. The horse was suspected to have an inflammatory lesion of the interosseous tendon, but treatment had resulted in only a minimal response. Shortly after diagnostic arthrocentesis of the left metacarpophalangeal joint was performed, the joint became severely swollen, and radiography of the area revealed lysis of the distal end of the third metacarpal bone, the proximal sesamoid bones, and the proximal end of the proximal phalanx. The horse did not respond to treatment and was euthanatized. At necropsy, severe erosive arthritis and degenerative osteomyelitis of the left metacarpophalangeal joint were seen. Swab specimens of the ulcerated lesions of the articular cartilage were submitted for microbial culture, and Scedosporium prolificans was isolated. Scedosporium prolificans is a newly recognized opportunistic fungal pathogen of humans and animals. In humans, S prolificans typically causes focal locally invasive infections that primarily involve musculoskeletal tissues; most often, infection is a result of penetrating trauma or surgical incision. In immunocompromised patients, fatal disseminated infection can occur. The fungus is resistant to almost all currently available antimycotic agents.     

Multisystemic granulomatous inflammation in a horse

A one-year-old Thoroughbred filly was examined because of poor body condition and reluctance to move its neck. Complete blood count revealed leukocytosis (15,700 WBC/microliters) and hyperproteinemia (8 g/dl). Radiography of the cervical vertebrae revealed multifocal lesions of bone lysis surrounded by zones of sclerosis. The horse was euthanatized and necropsied. Granulomatous lesions were identified in the heart, spleen, lungs, bones, and lymph nodes. The multifocal granulomatous inflammatory lesions in this horse were suggestive of mycobacteriosis.     

Polyostotic lymphoma with multiple pathological fractures in a six-month-old cat

A 6-month-old female neutered domestic shorthair cat was examined for pain and swelling of the distal limbs. Swelling and malalignment of both carpi, dorsiflexion of the distal metatarsals and a mild, multicentric lymphadenopathy were detected on examination. Screening blood tests revealed a biclonal gammopathy, hypercalcemia and atypical leukocytes. Survey radiographs revealed lysis and proliferative changes within the physes. Multiple pathological physeal fractures were present, including the distal radii, metacarpal and metatarsal bones. No treatment was attempted and the patient was euthanased. Histopathology revealed infiltration by monomorphic round cells within the liver, spleen, kidney and bone marrow. Immunohistochemistry revealed strong reactivity to CD20. Clonality assays revealed clonal results for the B-cell loci, consistent with B-cell lymphoma. To the authors' knowledge this is the first report of polyostotic lymphoma with multiple pathological fractures in a cat. The predominantly distal distribution of osseous lesions is rarely reported in dogs and humans.     

Orbital apex syndrome secondary to an orbital sarcoma in a dog

A 12-year-old castrated male cocker spaniel dog was presented with a 4-week history of left episcleral injection and pawing at the face. Clinical examination findings included left internal and external ophthalmoplegia, left dorsal strabismus, pain opening the mouth, and intermittent amaurosis. Imaging studies revealed a left orbital apex mass with adjacent sphenoid bone lysis and extension into the cranial cavity. A left exenteration was performed and histopathology confirmed an orbital soft tissue sarcoma.Key clinical message:This report describes an orbital tumor causing orbital apex syndrome. This condition should be differentiated from cavernous sinus syndrome as the latter does not course with optic neuropathy.     

Fungal osteomyelitis of the axial border of the proximal sesamoid bones in a horse

CASE DESCRIPTION: A 12-year-old Standardbred gelding was referred for swelling of the right metacarpophalangeal joint. CLINICAL FINDINGS: Ultrasonography of the right metacarpal area revealed hypoechoic areas in the right digital sheath and metacarpophalangeal joint consistent with synovial effusion. Radiography of the right metacarpophalangeal joint revealed lysis of the axial border of the proximal sesamoid bones. Aspergillus fumigatus was detected on fungal culture of synovial fluid. TREATMENT AND OUTCOME: Regional limb perfusion (150 mg of amikacin in 60 mL of saline [0.9% NaCl] solution perfused for 30 minutes) was performed 2 and 4 days after admission. Itraconazole (5 mg/kg [2.27 mg/lb], PO, q 24 h) was administered for approximately 9 weeks. Joint lavage with amikacin (500 mg) in 1 L of saline solution was performed 4 times. Three months after discharge, the owner reported that the horse was mildly lame during trotting but was moving freely and comfortably during all gaits and had gained a considerable amount of weight. Because the osteoarthritis was not expected to improve and because it was recommended that the horse not return to purposeful exercise, the owner decided to retire the horse from racing. CLINICAL RELEVANCE: Various diagnostic imaging methods and fungal cultures are useful for diagnosing fungal osteomyelitis of the axial borders of the proximal sesamoid bones in horses. Fungal osteomyelitis of the sesamoid bones and erosive arthritis should be considered as a differential diagnosis for horses in which corticosteroids have been administered intra-articularly.     

Primary cardiac tumor presenting as left ventricular outflow tract obstruction and complex arrhythmia

An adult female mixed breed dog presented for recurrent collapsing episodes over several weeks. Holter evaluation revealed periods of sinus arrest and echocardiography identified a soft tissue mass with subsequent severe dynamic obstruction of the left ventricular outflow tract. The patient was euthanized five days after presentation for severe dyspnea. Necropsy revealed an irregular mass circumferentially lining the left ventricular outflow tract as well as multiple myocardial metastases. The final diagnosis was an undifferentiated pleomorphic endocardial sarcoma.     

Calvarial hyperostosis presenting as unilateral exophthalmos in a female English Springer Spaniel

A 4-month-old intact female English Springer Spaniel presented to the University of Georgia Veterinary Teaching Hospital for evaluation of unilateral, progressive exophthalmos oculus sinister (OS) of 2 weeks' duration. Complete ophthalmic examination revealed moderate OS exophthalmos and lateral globe deviation. No other abnormalities were noted on physical or ophthalmic examination, ocular ultrasound, complete bloodwork, or thoracic radiography. Skull computed tomography (CT) revealed a large, focal, smoothly irregular, cavitated, expansile bony lesion involving the left caudal maxillary and left frontal bones. Biopsies, obtained through a frontal sinusotomy approach to preserve the left globe integrity, demonstrated normal reactive trabecular bone with locally extensive fibrosis. Calvarial hyperostosis was diagnosed based upon appearance on imaging, lesion unilaterality, absence of mandibular involvement, and histopathology. Six months after initial presentation, skull CT was repeated and marked reduction in the degree of frontal bone thickening was demonstrated with complete resolution of cavitations. There was marked clinical improvement with mild, nonpainful exophthalmos, and lateral globe deviation OS on ophthalmic examination. Eleven months after initial presentation, there was complete resolution of the frontal bone lesion with mild thickening of the left calvarial bones on repeat skull CT. There was no exophthalmos or globe deviation present on clinical ophthalmic examination. The proliferative osteopathic lesion was self-resolving with resolution of the exophthalmos and has not recurred to date. To the authors' knowledge, this is the first report of calvarial hyperostosis in a previously unreported breed presenting as unilateral exophthalmos.     

Presumed post‐traumatic ocular chondrosarcoma with intrathoracic metastases in a cat

An indoor‐only, 5‐year‐old, spayed female domestic shorthair cat presented for an ophthalmic examination of the left eye. An intraocular tumor with secondary glaucoma and blindness was diagnosed; the globe was enucleated and sent for histopathological examination. Gross examination revealed a solid white mass filling the entire vitreous space and replacing the iris and ciliary body. The lens and retina appeared to be similarly replaced by the neoplasm. Histological examination revealed a complete loss of the internal ocular structures, with a ruptured capsule as the only remnant of the lens within an extensive malignant mesenchymal neoplastic cell proliferation. The cells were polygonal, with well‐defined cytoplasmic borders and abundant weakly basophilic cytoplasm, embedded within the islands of chondroid matrix. No neoplastic invasion of the sclera was apparent. The animal died 6 months after the enucleation due to respiratory distress. Gross examination revealed numerous firm, white to tan nodular masses with smooth to mildly irregular surfaces dispersed throughout the parietal pleura, thoracic surface of the diaphragm, tracheobronchial and mediastinal lymph nodes, pericardium, and lungs. On cross‐section, the neoplastic nodules were solid and variably translucent, resembling hyaline cartilage. Histologically, these nodules were similar to the neoplasm identified earlier in the left globe. Metastasis of post‐traumatic ocular chondrosarcoma has not yet been described in cats. This is therefore believed to be the first report of metastases of this type of neoplasm in cats. This case adds to the limited set of data on the outcome of this type of tumor.