Meningioma and glioma as the first collision brain tumour reported in small animals.

We describe the clinical and pathological features of a brain collision tumour consisting of a fibrous meningioma and an anaplastic oligoastrocytoma in a 14-year-old male neutered French Bulldog. Computed tomography of the brain revealed a poorly defined, intra-axial lesion affecting the left frontal lobe. Following euthanasia, histological examination showed an anaplastic oligoastrocytoma invading the brain parenchyma and an adjacent fibrous meningioma. As synchronous intracranial tumours are rare in animals, the aims of this report are to describe the clinical, imaging and histopathological features of an intracranial collision tumour in a dog and highlight the importance of a complete histopathological study despite the imaging findings.

Hepatosplenic lymphoma and visceral mast cell tumor in the liver of a dog with synchronous and multiple primary tumors.

An 11-year-old spayed female American Cocker Spaniel was presented with a 4-week history of anorexia and a 1-week history of abdominal distension. Clinicopathologic and imaging abnormalities included intra-abdominal hemorrhage, granular lymphocytes (GLs) in abdominal fluid smears, a splenic mass, and hepatomegaly with diffuse multiple hypoechogenic nodules. Based on the cytologic, histologic, and immunohistochemical evaluation of the spleen and liver, the diagnosis was hepatosplenic T-cell lymphoma (HSTCL) of GLs. Postoperatively, the dog was maintained in good condition with chemotherapy (ACNU [nimustine], L-asparaginase, and prednisolone). However, on day 85, ultrasound-guided fine-needle aspiration of the liver revealed a proliferation in neoplastic mast cells not associated with the GLs. The dog was diagnosed with a visceral mast cell tumor (MCT) originating from the liver. The chemotherapy was switched to vinblastine and toceranib. The dog remained in good condition until day 141 but died due to the progression of MCT on day 158. Liver cytology on day 155 showed no GLs, although HSTCL is thought to be resistant to chemotherapy. After the definitive diagnosis of HSTCL, we monitored this patient's response to chemotherapy with blood tests, including complete blood counts, ultrasound imaging, and cytologic aspirates of liver. Although canine HSTCL has a poor prognosis, the possibility of a new neoplasm, including visceral MCT, should be considered. Periodic liver cytology might be worthwhile in dogs receiving chemotherapy for HSTCL.

Immunohistochemical Profile of Ameloblastic Carcinoma Arising from an Amyloid-Producing Odontogenic Tumour in a Miniature Dachshund.

A 13-year-old female miniature dachshund was presented with a centrally-located sublingual mass in the rostral mandibular region. The focally ulcerated growth completely covered the left (305) and right (405) premolar teeth and partially covered the right canine teeth (404). A punch biopsy sample revealed neoplastic proliferation of odontogenic epithelium arranged in irregular cords with frequent comedo-like necrosis. Following the initial diagnosis of ameloblastic carcinoma, a bilateral rostral hemimandibulectomy was performed. Although the detailed examination of the resected mass was consistent with the initial diagnosis, it also contained birefringent congophilic, amelogenin-labelled amyloid deposits similar to an amyloid-producing odontogenic tumour (APOT) in 30-40% of the mass, in continuity with the ameloblastic carcinoma. All neoplastic cells had diffuse moderate expression of cytokeratin (CK) AE1/AE3 and CK5, diffuse mild expression of CK14 and multifocal moderate expression of CK19. Because the APOT-like growth in the mass was histologically benign, the tumour was diagnosed as an ameloblastic carcinoma arising from an APOT.

Tumour-to-Tumour Metastasis Phenomenon: Metastatic Prostatic Adenocarcinoma within an Anaplastic Oligodendroglioma in the Brain of a Dog.

A 10-year-old entire male French bulldog was presented following clusters of generalized tonic-clonic epileptic seizures. Neurolocalization was consistent with a lesion in the left forebrain. Magnetic resonance imaging of the brain revealed a large, ill-defined, intra-axial, space-occupying lesion at the level of the left temporal and parietal lobes, causing marked compression of the adjacent parenchyma. Computed tomography of the thorax and abdomen was consistent with disseminated metastatic disease. The dog was humanely destroyed and subjected to necropsy examination. Histological examination of the brain revealed a metastasis of prostatic carcinoma within an anaplastic oligodendroglioma in the left forebrain. To the author's knowledge, this is the first report describing clinical, imaging and histopathological features of an intracranial tumour-to-tumour metastasis in the brain of a dog.

Mast cell and plasma cell collision tumor in the spleen of a dog.

A 9-year-old spayed female English Mastiff was referred for outpatient ultrasound due to a 3-week history of weight loss, vomiting, and decreased appetite. Abdominal ultrasound showed multiple splenic masses of varying sizes and serum chemistry panel showed hyperglobulinemia. Cytologic examination of fine-needle aspirates of the splenic masses indicated a mast cell and plasma cell collision tumor. Results of serum and urine protein electrophoresis and immunofixation indicated the plasma cell neoplasia was producing IgA immunoglobulins.

Carcinoma in situ within an area of Barrett esophagus in a dog with megaesophagus.

A 10-y-old Irish Setter was presented with a history of recurrent episodes of regurgitation and vomiting, with more recent development of tachypnea. Megaesophagus had been diagnosed in the dog 2 y prior to this presentation. A solitary polypoid mass present immediately rostral to the lower esophageal sphincter was biopsied during percutaneous endoscopic gastrostomy tube placement. Barrett esophagus was diagnosed based on the observation of a polypoid mass with intestinal metaplasia that arose from the surrounding esophagus. Histology of the polypoid mass demonstrated squamous-to-columnar metaplasia, hyperplasia, dysplasia, and carcinoma in situ.

Biphasic malignant melanoma adenocarcinoma in the digit of a dog.

A 7-y-old Black Russian Terrier dog was evaluated for chronic lameness of the right forelimb and concurrent weight loss. Clinical examination revealed a pigmented mass arising from digit 4 of the right forelimb; the digit was amputated and submitted for histologic evaluation. Histologically, the neoplasm was composed of ill-defined streams, sheets, and clusters of melanocytes admixed with a distinct population of malignant epithelial cells forming glands and nests. The diagnosis was a biphasic malignant melanoma adenocarcinoma, a rarely reported neoplasm in human medicine that has not been described in veterinary medicine, to our knowledge.

Concomitant Malignant Pulmonary Peripheral Nerve Sheath Tumour and Benign Cutaneous Peripheral Nerve Sheath Tumour in a Dog.

Peripheral nerve sheath tumours (PNSTs) are neoplastic growths derived from Schwann cells, perineural cells or both. Malignant PNSTs (MPNSTs) are uncommon in domestic animals. This report describes the concomitant occurrence of PNSTs in a 10-year-old female cocker spaniel with a clinical history of respiratory impairment. Grossly, there was a large infiltrative mass in the caudal lobe of the right lung; smaller nodules were observed in the other lobes of the right lung. Furthermore, a small encapsulated cutaneous nodule was observed on the left hindlimb. Histopathology of the pulmonary tumours revealed the proliferation of pleomorphic spindle-shaped cells with moderate mitotic index arranged in interwoven bundles and concentric Antoni A and Antoni B patterns; invasion of the adjacent pulmonary tissue was observed. The cutaneous nodule consisted of neoplastic mesenchymal cells in interwoven bundles with concentric whorls, but without the marked anisokaryosis, binucleation and infiltrative growth seen in the pulmonary tumour. Immunohistochemistry revealed that both tumours were immunoreactive for vimentin, glial fibrillary acidic protein and S100 protein, but were negative for factor VIII. These findings are indicative of a MPNST in the lung with a concomitant benign PNST in the limb. This case represents the first report of a primary MPNST in the lung of a dog. This neoplastic growth should be included in the differential diagnosis of primary malignant pulmonary tumours of dogs.

Diagnosis and treatment of concurrent dermal malignant melanoma and melanocytomas in a pygmy hippopotamus (Choeropsis liberiensis).

BACKGROUND: Dermal melanocytic neoplasms are common in some even-toed ungulates (Artiodactyla), yet this entity has not been reported in the pygmy hippopotamus to date. Concurrent occurrence of multiple benign and malignant melanocytic neoplasms is unusual. Malignant transformation occurs in a small percentage of benign melanocytic tumours in people but this phenomenon has not been well documented in animals. OBJECTIVES: To report the diagnosis and treatment of concurrent dermal melanocytomas and malignant melanomas in a pygmy hippopotamus. ANIMALS: A 36-year-old intact male pygmy hippopotamus, part of a zoological collection, housed with a 10-year-old female of the same species, presented with multiple raised and pigmented skin masses. METHODS: Initial impression smears of one ulcerated lesion were consistent with inflammation; subsequent histopathological findings from a skin biopsy revealed an underlying malignant melanoma. The animal was anaesthetised, ultrasonographic imaging of the local lymph nodes indicated no local involvement and all skin lesions were removed. Recovery from anaesthesia was unremarkable, skin healing was within normal limits for the species. There was no sign of recurrence 34 months post-surgery. RESULTS: A diagnosis of malignant melanomas and concurrent melanocytomas was made on histopathological evaluation. CONCLUSION AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first reported case of melanocytic neoplasia in the pygmy hippopotamus. The occurrence of both benign and malignant melanocytic skin tumours should be considered in this species.

Concurrent with T-zone lymphoma and high-grade gastrointestinal cytotoxic T-cell lymphoma in a dog.

A 9-year-old, spayed female Golden Retriever dog was referred to us for lymphocytosis and lymphadenopathy, secondary to suspected chronic lymphocytic leukemia (CLL). The dog had a clinical history of anorexia, vomiting and melena lasting two days. The popliteal lymph node contained small-to-intermediate lymphocytes, which led us to suspect low-grade lymphoma. Thickened lesions in the stomach and small intestine were detected by ultrasonography. Histopathology of the popliteal lymph node and small intestine revealed a simultaneous presence of T-zone lymphoma (TZL) and high-grade gastrointestinal (GI) cytotoxic T-cell lymphoma. Large granular lymphocytes (LGLs) were seen on cytological examination. Polymerase chain reaction (PCR) revealed that both lymphomas originated in the T-cells. The dog died 15 days after diagnosis, despite chemotherapy.

A statistical assessment of the biological relationship between simultaneous canine mammary tumours.

Simultaneous canine mammary tumours (CMTs) are frequently reported in the literature, but few studies have addressed their biological relationship in detail or performed statistical assessments. In this study, 269 canine mammary gland tumours from 216 dogs were categorized using an extended histopathological classification, where semiquantitative and binomial scales enumerated morphological parameters of the tumours. The classification facilitated a statistical study of the biological relationship between simultaneous within-dog tumours. Seventy-seven percent of the dogs had single tumours and 23% had simultaneous tumours. Sixty-one percent of the neoplasias were benign, with complex adenoma as the most frequent diagnosis and 39% were malignant, with complex carcinoma as the most common malignancy. Simultaneous tumours within dogs more often had equal diagnoses and neoplastic level (benign or malignant) than would be expected by chance alone, as compared with random pairs of single tumours from different dogs. This statistically supported finding indicated the presence of a biological relationship between simultaneous tumours.

Detection of synchronous primary tumours and previously undetected metastases in 736 dogs with neoplasia undergoing CT scans for diagnostic, staging and/or radiation treatment planning purposes.

The purpose of our study was to describe synchronous primary tumours and previously undetected metastases in 736 dogs with confirmed neoplasia in which computed tomography (CT) scans were performed for diagnostic, staging and/or radiation treatment planning purposes. All CTs were reviewed by a radiologist. Tumour-associated CT abnormalities were detected in 38/736 (5%), including confirmed or suspected synchronous primary neoplasms (n = 24), metastases of the primary tumour (n = 9) or both (n = 3). In lymph nodes (LN) that were considered abnormal on CT scan and were aspirated, 23% contained metastasis, and 6% of 'normal' appearing LN that were aspirated contained metastasis. Thorough evaluation of CTs and routine aspiration of regional LN are critical because results affect recommendations to perform additional staging tests and treatment for the primary and secondary tumour(s).

Concurrent Gliosarcoma and Choroid Plexus Carcinoma in a Cow.

Brain tumours in cattle are uncommon and the spontaneous development of primary brain tumours of different histological types is rare in both man and animals. In man, multiple concurrent primary tumours of different types are occasionally described. We report the rare simultaneous occurrence of two different primary brain tumours, gliosarcoma and choroid plexus carcinoma, diagnosed by microscopical and immunofluorescence evaluation in an 8-year-old cow with a 2-month history of neurological disease. Gliosarcoma is a rare variant of glioblastoma multiforme, characterized by the presence of malignant glial cells and mesenchymal tissue. This tumour has not been reported previously in animals.

Collision Tumour of Squamous Cell Carcinoma and Malignant Melanoma in the Oral Cavity of a Dog.

A 7-year-old, male cocker spaniel was presented with a gingival proliferative lesion in the rostral maxilla and enlargement of the regional lymph node. Morphological and immunohistochemical analysis revealed a collision tumour composed of two malignant populations, epithelial and melanocytic, with metastasis of the neoplastic melanocytes to the regional lymph node. The epithelial component consisted of trabeculae and islands of well-differentiated squamous epithelium immunoreactive to cytokeratins. The melanocytic component had a varying degree of pigmentation of polygonal and spindle-shaped cells, growing in nests or densely packed aggregates and immunolabelled with S100, melanoma-associated antigen (melan A), neuron-specific enolase and vimentin antibodies. Protein markers involved in tumorigenesis or cell proliferation (i.e. COX-2, p53, c-kit and Ki67), were overexpressed by the neoplastic cells. To the authors' knowledge, this is the first description of an oral collision tumour involving malignant melanoma and squamous cell carcinoma in the dog.

Concurrent Transitional Meningioma and Ceruminous Gland Adenocarcinoma in a Scottish Wildcat Hybrid (Felis silvestris).

The Scottish wildcat (Felis silvestris) is an iconic and endangered subpopulation of the European wildcat (F. silvestris silvestris). There is much research devoted to the ecology, genetics and conservation of this animal, but little published information on pathology and disease. The investigation and reporting of such information is vital to furthering understanding of the effects of hybridization, a factor that is crucial if we are to secure a future for the Scottish wildcat. This report describes the clinical presentation, gross post-mortem and histological findings in an elderly Scottish wildcat hybrid with concurrent transitional meningioma and ceruminous gland adenocarcinoma.

The co-existence of a myxoid liposarcoma and leiomyoma in the same ovarian mass of a dog.

A 15-year-old, female mixed-breed dog presented with abdominal distention. An exploratory laparotomy revealed a large left ovarian mass (20 × 15 × 12 cm). Histopathological examination of the mass revealed a mixed myxoid liposarcoma and a well-differentiated leiomyoma. Four months after surgical removal of the mass, the dog died due to multiorgan metastasis. The metastasis was composed solely of the liposarcoma component. The liposarcoma component was Alcian Blue- and Oil red O-positive, and demonstrated immunoreactivity with S-100, adipophilin and vimentin. Electron microscopy revealed that the tumor cell cytoplasms were packed with lipid vacuoles and dilated rough endoplasmic reticulum. To our knowledge, this is the first report of myxoid liposarcoma and leiomyoma co-existing in a canine ovary.

Simultaneous Occurrence of Pancreatic Adenocarcinoma and Brunner's Gland Adenoma in a Siberian Tiger (Panthera tigris altaica).

We describe a case of pancreatic adenocarcinoma and Brunner's gland adenoma in an 18-year-old male Siberian tiger (Panthera tigris altaica) from the Ljubljana Zoo. The tiger was humanely destroyed due to weakness and progressive weight loss. Necropsy examination revealed a large, grey, predominantly necrotic mass replacing the major part of the pancreatic body. Microscopically, the mass was unencapsulated, poorly demarcated, highly cellular and composed of highly pleomorphic, cuboidal to tall columnar cells with basal, round or oval, moderately anisokaryotic nuclei with prominent nucleoli and moderate to large amounts of eosinophilic cytoplasm. The tumour was diagnosed as pancreatic tubular adenocarcinoma with infiltration into the duodenum and mesentery. There were tumour emboli in mesenteric blood vessels and hepatic metastases. The non-affected part of the pancreas exhibited severe chronic pancreatitis. In addition, one firm white neoplastic nodule was observed in the duodenal wall. The nodule was set in the tunica muscularis and was unencapsulated, well demarcated and highly cellular, and consisted of a closely packed layer of normal Brunner's glands and a centrally positioned group of irregularly branched tubules with small amounts of debris in the lumen. The neoplastic nodule was diagnosed as Brunner's gland adenoma. The present case is, to the best of our knowledge, the first report of concurrent pancreatic adenocarcinoma and Brunner's gland adenoma, most probably induced by chronic pancreatitis, either in man or animals.