Anterior uveal spindle cell tumor in a cat

Purpose To describe a case of anterior uveal spindle cell tumor in a cat with features similar to spindle cell tumor of blue eyed dogs. Methods A 10‐year‐old female spayed domestic short‐haired cat was referred for an iris mass OS. The mass was solitary, nodular, nonpigmented, located medially, and causing dyscoria. A diagnosis of a benign epithelial tumor was suggested by a FNA of the mass. The cat was lost to follow‐up for 2 years, after which time she re‐presented with glaucoma, blindness and grossly evident iridal mass enlargement OS. Transconjunctival enucleation was performed and the globe submitted for histopathology. Results Histopathology of the enucleated globe revealed the superior iris to be infiltrated and effaced by a large population of neoplastic spindle cells. The cells were arranged in streams and bundles and exhibited Antoni‐A and Antoni‐B tissue patterns, which are characteristic of Schwann cell tumors. Mitotic figures were rare and cellular pleomorphism moderate. Immunohistochemical staining was positive for S‐100 protein and glial fibrillary acidic protein (GFAP), and negative for Melan‐A. Interestingly, there was no histological evidence of glaucoma. Conclusions Based on its histopathologic characteristics, this iris tumor was diagnosed as a Schwann cell variant of a peripheral nerve sheath tumor (PNST) closely resembling the spindle cell tumor of blue‐eyed dogs. Anterior uveal PNST has not been previously reported in cats to the authors’ knowledge. The presence of Antoni type A and type B tissue patterns along with immunohistochemical staining may facilitate a diagnosis of PNST and rule out malignant melanoma.     

Right ventricular rupture after lateral thoracotomy for removal of rib-associated telangiectatic osteosarcoma in a dog

Objective – To describe a case of a focal right ventricular rupture following removal of a rib-associated telangiectatic osteosarcoma (TOS) in a dog.
Case Summary – A 2-year-old spayed female mixed-breed dog, weighing 20 kg, was presented in compensated hypovolemic shock due to active bleeding into the thoracic cavity. The dog was stabilized with appropriate fluid administration. Subsequent computed tomographic examination revealed a large mineralized mass originating from the body of a rib and displacing the heart. Two days after surgical removal of this mass, focal right ventricular rupture occurred and the dog died. The mass was later identified as a TOS.
New or Unique Information Provided – Although hemothorax secondary to TOS has been described previously, this report describes for the first time, spontaneous focal right ventricular rupture as a rare complication of thoracotomy and rib resection for the removal of a rib-associated, intrathoracic TOS.     

Hemidiaphragmatic reconstruction with a transversus abdominis muscle flap after resection of a solitary diaphragmatic mesothelioma in a dog

CASE DESCRIPTION: A 2-year-old Siberian Husky was evaluated because of a 2-week history of coughing and gagging and decreased appetite and activity level. CLINICAL FINDINGS: Radiography, surgery, and immunohistochemical examination revealed a solitary sclerosing mesothelioma extending from the left thoracic diaphragmatic surface that was adherent to the pericardium and the caudal mediastinum. TREATMENT AND OUTCOME: The tumor was resected along with most of the left hemidiaphragm, and the left transversus abdominis muscle was used to reconstruct the diaphragm. The 13th rib formed the base of the muscle flap. The muscle flap was transposed into the defect so that the mesothelium-lined surface faced the thoracic cavity and the deep aspect of the muscle formed the abdominal surface of the diaphragm. To minimize risk of adhesions, the exposed raw aspect of the abdominal surface was covered with porcine small intestinal submucosa. Recovery was uncomplicated, and the dog's appetite and activity level soon returned to normal. Evaluation 54 days after surgery revealed 2 subcutaneous masses on the thorax and masses in the liver and both kidneys; histologic and immunohistochemical analyses revealed metastasis of the original tumor. The dog was euthanatized. CLINICAL RELEVANCE: Hemidiaphragmatic reconstruction with a transversus abdominis muscle flap after resection of a diaphragmatic tumor was successful. The muscle flap was easily harvested and transposed into the diaphragmatic defect.     

Malignant peripheral nerve sheath tumor of the diaphragm in a dog

An 11-year-old, castrated male greyhound was referred to the Michigan State University Veterinary Teaching Hospital for surgical removal of a thoracic mass. Thoracic radiographs revealed a smoothly marginated mass obscuring the diaphragm in the left caudal thorax. Ultrasonographic and computed tomographic imaging modalities demonstrated a mass originating from the left hemidiaphragm. The mass was surgically removed and submitted for histopathological evaluation. Histopathology and immunohistochemical staining confirmed a malignant peripheral nerve sheath tumor.     

Acute hindlimb paresis caused by extension of a peripheral nerve sheath tumour into the spinal canal of a horse

A 10-year-old Quarter Horse gelding presented for a large, slowly growing mass in the right thoracic region caudal to the withers (approximately at the level of thoracic vertebrae 10 to 16). The mass was surgically removed, the horse returned to normal riding activity, and no external regrowth was observed. Two years after surgery, the horse developed progressive signs of hindlimb weakness, ataxia and adopting a dog-sitting stance. Post-mortem examination confirmed spinal canal infiltration and spinal cord compression (at the level of the 12th thoracic vertebra) by a similar soft tissue sarcoma as diagnosed previously. Immunohistochemistry confirmed the tumour as a peripheral nerve sheath tumour (PNST) likely originating from the twelfth thoracic spinal nerve. This report demonstrates that with incomplete tumour resection, local recurrence and extension of a PNST into the central nervous system can occur even years after initial tumour removal. Immunohistochemistry to differentiate the type of soft tissue sarcoma in cases with close association to the nervous system may prove beneficial to anticipate this uncommon complication. Early surgical resection with adjunctive therapies should be considered in these cases.     

Intraocular peripheral nerve sheath tumor in a dog

A tumor within the right globe in a 9-year-old Shetland sheepdog was examined pathologically. The tumor was composed of spindle or oval cells arranged in interwoven bundles with intervening collagenous or mucinous matrices. Immunohistochemically, the tumor bound antibody directed to S-100 protein and vimentin, but not to desmin, actin smooth muscle, or neurofilament. Electron microscopy revealed that the tumor cells had poorly developed cytoplasmic processes, desmosomes between closely contiguous cells, and a discontinuous basement membrane-like material. Based on these findings, the tumor was diagnosed as a peripheral nerve sheath tumor (PNST) histologically. To the authors' knowledge, this is the first reported case of intraocular PNST in dogs.     

Spontaneous external biliary fistula in a dog

CASE DESCRIPTION: A 10-year-old sexually intact female dog was examined because of a static, well-circumscribed subcutaneous mass and associated fistulous draining tract located along the right ventrolateral aspect of the thoracic body wall of 15 months' duration. CLINICAL FINDINGS: Results of computed tomography and fistulography confirmed the presence of the fistulous tract. Computed tomography also revealed a focal, hypodense region in the right ventral portion of the liver that was adjacent to but not clearly associated with the fistulous tract. TREATMENT AND OUTCOME: Surgical exploration of the tract revealed that it passed into the right hemithorax to the diaphragm; entered the right medial lobe of the liver; and terminated in a well-encapsulated, cystic liver lesion. The right medial liver lobe and all affected tissues were removed. Histologically, the liver lesion consisted of a fibrotic, dilated bile duct. The dilated bile duct and fistula were lined with biliary epithelium. On the basis of these findings, a diagnosis of spontaneous external biliary fistula was made. Five months after surgery, the dog was clinically normal. CLINICAL RELEVANCE: To the authors' knowledge, spontaneous external biliary fistula in a dog has not been reported in the veterinary medical literature. Despite the rarity of this condition, it should be considered in a dog with similar clinical findings. Clinical findings and results of appropriate diagnostic imaging procedures may provide valuable information in making this diagnosis and in planning surgical treatment.     

Hemorrhagic bile pleuritis and peritonitis secondary to traumatic common bile duct rupture,diaphragmatic tear,and rupture of the spleen in a dog

Objective– To describe the diagnosis and successful treatment of bile pleuritis and peritonitis secondary to traumatic rupture of the common bile duct and a diaphragmatic tear in a young dog. Case Summary– A 1‐year‐old German Shepherd dog was referred for evaluation of vomiting and icterus 4 days after being hit by a car. Thoracic radiographs, thoracic and abdominal ultrasonographic examinations, thoraco‐ and abdominocentesis, and positive contrast celiogram indicated hemorrhagic pleuritis and peritonitis, left dorsal diaphragmatic tear, and rupture and infarct of the spleen. Surgical exploration of the abdomen confirmed these findings in addition to a circumferential tear of the common bile duct, leading to a diagnosis of hemorrhagic bile pleuritis and peritonitis. Aerobic and anaerobic bacterial culture of the abdominal fluid yielded no growth. Surgical correction of the traumatic injuries was achieved via common bile duct anastomosis, cholecystojejunostomy, repair of the diaphragm, and splenectomy. The dog developed postoperative signs consistent with aspiration pneumonia but was successfully treated and discharged from the hospital. Clinical signs and laboratory abnormalities resolved and the dog was alive and healthy 8 months after discharge. New or Unique Information Provided– Bile pleuritis is rare in dogs and cats and is usually associated with penetrating, not blunt, abdominal trauma. Multiple organ injury in cases of traumatic bile duct rupture is uncommon; in this dog, rupture of the common bile duct was accompanied by rupture of the diaphragm and spleen.     

Primary mesenteric root osteosarcoma in a dog

Abstract: A 10‐year‐old spayed female Boxer‐mix was presented with a history of several weeks of soft stools, straining to defecate, inappetance, and lethargy and several days of hematochezia, melena, and dyschezia. Physical examination findings included mild tachycardia and tense cranial abdomen. CBC results indicated moderate mature neutrophilia. Ultrasonographic examination of the abdomen revealed a large mass with complex echogenicity in the cranial abdomen, likely associated with the intestines. Cytologic examination of a fine‐needle aspirate revealed a population of round, stellate, and spindle‐shaped cells arranged individually and in aggregates with occasional cells embedded in an eosinophilic extracellular matrix. The cytologic interpretation was malignant mesenchymal neoplasm with osteosarcoma being the primary differential. Surgical exploration of the abdomen revealed a 10‐cm‐diameter mass located at the intestinal mesenteric root. The mass occluded blood flow to portions of the gastrointestinal tract. The dog was euthanized due to the nonresectable nature of the tumor. Histopathologic examination revealed an expansile poorly demarcated mesenchymal neoplasm composed predominantly of spindloid and pyriform cells, occasionally embedded in a matrix compatible with osteoid. The diagnosis was extraskeletal osteosarcoma of the intestinal mesenteric root, only rarely reported in dogs.     

Diagnosis and Treatment of Anaplastic Mammary Carcinoma in a Sugar Glider (Petaurus breviceps)

A 9-year-old female sugar glider (Petaurus breviceps) was evaluated for a tissue mass near the marsupium. Ultrasonography identified a vascular mass originating from the right mammary gland. Fine-needle aspiration was suggestive of a malignant neoplasm. The glider was anesthetized and the tumor was removed, and this was followed by strontium-90 plesiotherapy to the tumor bed in an attempt to decrease local recurrence. Histopathology revealed an anaplastic mammary carcinoma. The glider was euthanized less than 14 days after the procedure owing to self-mutilation behavior of unknown etiology. This report is the first to describe the clinical presentation, diagnostics, therapeutics, and treatment response for a sugar glider with mammary neoplasia.     

Systemic candidiasis in a dog, developing spondylitis

A 4-year-old male Shiba dog initially presented with pain of an undetermined origin and hypersensitivity to touch. Seven days later, the dog developed ataxia, hind-leg weakness and knuckling. The dog died on 20 days after presentation. Postmortem examination revealed a mass in the body of thoracic vertebra. Histopathologically, the mass consisted of granulomatous inflammation, including fungal organisms that were immunohistochemically positive for Candida albicans. Similar granulomatous lesions were observed in the systemic lymph nodes, kidneys, pancreas, spleen, prostate gland, thyroid glands and heart. This case was diagnosed as systemic candidiasis with spondylitis.     

Traumatic intracerebral hematoma in a dog: MR images and clinical findings

A nine-year-old, male, mongrel dog was unsteady after falling down a set of stairs. The dog exhibited a mildly abnormal gait 2 days after injury, and was not able to stand, with spasticity of the right limbs, 4 days after injury. MR imaging revealed a clearly demarcated mass on the top of the left lateral ventricle that showed mild hyperintensity on T1-weighted images and hyperintensity on T2-weighted images. The authors diagnosed the dog as having a traumatic intracerebral hematoma. This type of case, in which the clinical signs deteriorated due to edema associated with hematoma, is extremely rare.     

Paraneoplastic leukocytosis in a dog with a renal carcinoma

A 7-year-old male German Shepherd dog in poor body condition had a 3-month history of intermittent hematuria. Nonregenerative anemia, mild leukocytosis, marked hypoalbuminemia, and hematuria were observed. Subsequently, marked neutrophilia and moderate monocytosis were noted; anemia, hypoalbuminemia, and hematuria persisted; and the dog developed disseminated intravascular coagulation. Ultrasonographic examination of the abdomen revealed the presence of an enlarged and irregularly shaped right kidney with a large area of cavitation, and a nephrectomy was performed 30 days after initial examination. Cytologic examination of fine-needle aspirates and imprints of the right kidney revealed a neoplastic cell population suggestive of renal carcinoma. The histopathologic diagnosis was chromophobic cystic-papillary renal carcinoma. The tumor cells expressed granulocytic/macrophage-colony-stimulating factor (GM-CSF), detected by immunohistochemical staining, and elaboration of GM-CSF by the tumor may have mediated the leukocytosis in this dog. Following excision of the tumor, neutrophil and monocyte counts were only mildly increased. The dog died 135 days after initial presentation, and a necropsy was not permitted. Paraneoplastic neutrophilic leukocytosis is an uncommon finding and may be caused by elaboration of CSF by neoplastic cells.     

Neuroendocrine carcinoma of the nasopharynx in a dog

Neuroendocrine carcinoma of the nasopharynx was diagnosed in a 9-year-old male Golden Retriever. The mass was identified by computed tomography of the nasal cavity and nasopharyngoscopy, and it was surgically excised. Histologic, cytochemical, and electromicroscopic examination of specimens confirmed the type of tumor. The dog was clincally improved for 150 days but was then reexamined because of respiratory difficulty and poor appetite. Thoracic radiographs revealed multiple nodules in all lung lobes, and ultrasonography revealed a mass in the spleen. The dog died the next day.     

Urethral haemangiosarcoma in a boxer

A seven-year-old, entire female boxer presented with a history of restless behaviour and inappetence. Physical examination revealed that the dog was listless and had a hunched gait. Neurological examination was normal. Abdominal ultrasonography revealed a 4 cm x 4 cm mass in the cranial pelvic canal. Neurological abnormalities were detected three days after presentation, and progressed from proprioceptive deficits to loss of deep pain sensation in the pelvic limbs over a two-day period. The dog was euthanased and postmortem examination revealed that the pelvic mass was a urethral haemangiosarcoma with metastasis to the second lumbar vertebra. This case is unusual as urethral tumours are usually transitional cell carcinomas and frequently present with signs of dysuria.     

Secondary erythrocytosis associated with schwannoma in a dog

An 11-year-old, spayed female mixed-breed dog showed clinical signs of right forelimb lameness and pain by palpation around the neck. Radiography and computed tomography (CT) revealed an extradural mass at the 6th and 7th cervical vertebrae, which compressed the spinal cord. The mass was surgically removed and histopathologically diagnosed as schwannoma. The dog recovered her normal gait after hemilaminectomy and removal of the mass. Ten months after the surgery, the tumor recurred with absolute erythrocytosis and was surgically removed again. This removal temporarily resolved the erythrocytosis with a decrease in plasma erythropoietin (EPO) concentration. EPO protein was detected immunohistochemically in the tumor cells. Erythrocytosis in this dog may be caused by ectopic EPO produced in the schwannoma tissues.     

Use of a rivet-like titanium clamp closure system to replace an external frontal bone flap after transfrontal craniotomy in a dog

A 10-year-old spayed female dog was referred for surgical removal of a brain tumor that had been identified following an acute onset of seizure activity 2 weeks earlier. A computed tomographic evaluation involving contrast agent revealed the presence of a contrast-enhanced mass within the left olfactory lobe of the brain. After removal of the mass via a transfrontal craniotomy, the overlying frontal bone flap was replaced and secured by use of a biologically inert rivet-like titanium clamp closure system and 3 titanium alloy craniotomy line clamps. On reevaluation 4 weeks after tumor removal, the dog was free of seizure activity and had no proprioceptive deficits; according to the owner, the dog had marked improvement in its overall behavior and attitude. The titanium clamp closure system appears to offer an effective and rapid technique for the secure replacement of craniotomy bone flaps in dogs.     

Canine bicavitary carcinomatosis with transient needle tract metastasis diagnosed by multiplex immunocytochemistry

A 6‐year‐old, male castrated, mixed‐breed dog was referred to the James L. Voss Veterinary Teaching Hospital at Colorado State University for bicavitary effusion. On examination, the dog was tachycardic and tachypneic with bilaterally decreased lung sounds. Thoracic and abdominal ultrasonic examination revealed pleural and peritoneal effusions, which were aspirated and submitted for fluid analysis and cytology. Both cavity fluids were classified as exudates with a large population of vacuolated mononuclear cells. Multiplex immunocytochemistry (ICC) for cytokeratin and vimentin demonstrated exclusively cytokeratin expression, indicating these cells were of epithelial origin. A full diagnostic evaluation was performed, including CBC, clinical chemistry, a pet‐side test for heartworm disease, ehrlichiosis, Lyme disease, and anaplasmosis, imaging modalities of thorax, abdomen, and heart, urinalysis, and fine‐needle aspirations of spleen, liver, and popliteal lymph nodes. The dog was diagnosed with pleural and peritoneal carcinoma with presumed carcinomatosis. A single dose of intracavitary carboplatin was administered before discharge, and over a period of 2 weeks, 5 thoracocenteses were performed. A subcutaneous mass was noted at a thoracocentesis site one week after initial presentation. Cytology of the mass was consistent with carcinoma, and neoplastic seeding of the tumor cells from the thoracocentesis was suspected. The dog was euthanized 15 days after the first visit, and a necropsy was performed. Findings were consistent with carcinomatosis secondary to anaplastic pulmonary carcinoma with transient subcutaneous seeding of neoplastic cells during routine thoracocentesis. This case demonstrates the utility of multiplex ICC in the clinical setting.     

Femoral compartment syndrome due to haemangiosarcoma in the semimembranosus muscle in a dog

A five-year-old, entire male German shepherd dog was presented to the Veterinary Teaching Hospital-Koret School of Veterinary Medicine because of an acute, painful swelling of the right thigh and severe lameness of two-weeks duration. On physical examination, a firm and painful mass was detected in the hamstring region. Radiography and ultrasonography revealed a soft tissue mass, with a 250 cc fluid accumulation craniomedial to it. Intracompartmental pressure measurement with a Wick catheter demonstrated significantly elevated pressure within the right caudal femoral compartment (25 to 28 mmHg compared with 5 to 7 mmHg in the unaffected leg). Surgical exploration of the area was undertaken, fasciotomy and mass excision were performed, and resolution of the clinical signs was achieved. The mass was identified by histopathology results as haemangiosarcoma. Two and a half months after surgery, which was followed by adjunct chemotherapy (doxorubicin), the dog was readmitted with a subcutaneous mass in the same area, although he was not lame at this time. Radiographs of the thoracic cavity demonstrated widely disseminated metastases in the lungs. At that point, the owner elected to have the dog euthanased.     

Use of latissimus dorsi and abdominal external oblique muscle for reconstruction of a thoracic wall defect in a cat with feline osteochondromatosis

A 4-year-old, male castrated European shorthair cat was presented with a firm mass palpable on the right caudal rib cage. Lateral and ventrodorsal radiographs of the thorax revealed a 4x3x2cm large, expansile and radiodense mass originating from the distal part of the 13th rib. After removal of the tumour, which was histopathologically confirmed as feline osteochondromatosis, the diaphragm, omentum, external abdominal oblique and latissimus dorsi muscles were used to reconstruct the defect. Feline osteochondromatosis is induced by retroviruses, eg, feline leukaemia virus, for which the cat tested positive. The tumour was removed for palliative reasons, because such tumours have the tendency to transform into osteosarcomas. Six months after the surgical excision the cat showed no clinical signs of reoccurrence.