Primary Lymphangiosarcoma of the Urinary Bladder in a Dog.

Abdominal ultrasonographical and computed tomography examinations of a 12-year-old neutered female toy poodle revealed a protruding mass, approximately 2 cm in diameter, at the apex of the bladder. The mass was firm and haemorrhagic with a homogeneously brownish-yellow cut surface. Microscopically, it was unencapsulated and located in the muscle layer with invasion of the extra-muscular layer. It was composed of spindloid to oval neoplastic cells that formed irregular clefts and diffuse sheets that dissected bundles of collagen. Immunohistochemically, the neoplastic cells were positive for vimentin and lymphatic vessel endothelial hyaluronan receptor 1 antigens, but negative for cytokeratin AE1/AE3, factor VIII-related antigen, CD31, CD34, Prox-1, S100, desmin, α-smooth muscle actin and MyoD1. Negative immunolabelling for laminin antigen supported the absence of evidence of a basal lamina on ultrastructural examination. Based on these findings, this tumour was identified as a lymphangiosarcoma. To the best of our knowledge, this case is the first report of lymphangiosarcoma arising from the bladder in a dog.

Diffuse Pulmonary Meningotheliomatosis with Sarcomatous Transformation in a Shiba Dog.

A 2-year-old neutered female Shiba dog exhibited laboured breathing for 1 month. Computed tomography of the thoracic cavity revealed multiple nodules (2-5 mm diameter) in the lungs. Grossly, the lungs were firm and normal in shape. The nodules were grey-white in colour. Microscopically, the nodules were non-encapsulated and exhibited an irregular shape. They were composed of polygonal or spindle cells with indistinct cell borders arranged in sheets. The cells had large, round, hyperchromatic nuclei and abundant pale eosinophilic cytoplasm with no atypia. Intrapulmonary arterial emboli and infiltration into the bronchioles were observed. Immunohistochemically, the cells were positive for vimentin and negative for cytokeratin, glial fibrillary acidic protein and α-smooth muscle actin. Ultrastructurally, the cells displayed cytoplasmic processes, desmosomes and intermediate filaments. These findings led to a diagnosis of diffuse pulmonary meningotheliomatosis with sarcomatous transformation. To the best of our knowledge, this is the first report of diffuse pulmonary meningotheliomatosis in a dog.

Chronic Basophilic Leukaemia in a Dog.

A 13-year-old neutered female mixed-breed dog with a clinical history of emaciation, inappetence and vomiting for 2 months was presented. Blood tests showed marked leucocytosis with increased neutrophil and basophil count, mild thrombocytosis and anaemia. Seven days after the initial visit, the dog died and was submitted for necropsy examination. Grossly, the bone marrow was red in colour and hepatomegaly and splenomegaly with discolouration were observed. A bone marrow smear showed an increased proportion of basophilic lineage cells. Histologically, the bone marrow showed high cellular density and numerous basophilic lineage cells with a round or segmented nucleus. The cytoplasm contained basophilic granules exhibiting metachromasia on toluidine blue staining. Immunohistochemically, the neoplastic basophils were diffusely positive for vimentin and myeloperoxidase, but negative for CD3, BLA36, CD163, CD204 and c-kit. The immunohistochemical features of neoplastic basophils that had invaded the liver and spleen were similar to those of the basophils in the bone marrow. Based on the clinicopathological and histopathological findings, chronic basophilic leukaemia was diagnosed. The present case study provides insights into the pathological features of chronic basophilic leukaemia in dogs.

Pancreatic Colloid Carcinoma in an Elderly Cat.

A 21-year-old neutered female domestic shorthaired cat was presented with a history of inappetence, vomiting and haematuria. The cat was humanely destroyed at the owner's request and a necropsy examination was performed. A 0.8 × 0.5 × 0.5 cm mass was located in the left lobe of the pancreas. The mass was gelatinous in nature and the external and cut surfaces were pale yellow in colour. Microscopically, the mass was non-capsulated and comprised an accumulation of extracellular stromal mucin containing suspended neoplastic columnar epithelial cells forming tubular structures. Immunohistochemically, these cells diffusely expressed cytokeratin (CK) AE1/AE3, CK7 and carcinoembryonic antigen and were partially positive for CK19 and trypsin, but negative for vimentin. The tumour was diagnosed as a colloid carcinoma. The clinical presentation in this case was caused by chronic renal failure complicated by secondary renal hyperparathyroidism and associated metastatic calcinosis. To the best of our knowledge, this is the first report of colloid carcinoma arising from the pancreas in a cat.

Lingual Chondrolipoma in a Dog.

A 13-year-old female Yorkshire terrier was presented with difficulty swallowing because of a lingual mass, which had grown to a size of 0.8 × 0.8 × 0.8 cm in 1 month. Grossly, the mass was located in the lingual frenulum and the cut surface was grey-white in colour. Microscopically, the mass was unencapsulated and composed of lobules of mature adipose tissue and cartilaginous tissue with abundant basophilic myxoid matrix separated by fibrous connective tissue. Immunohistochemically, almost all of these cells were positive for vimentin and S100. Chondroid cells and their adjacent spindle cells were also positive for SOX9. Based on these findings, a diagnosis of chondrolipoma was made. To the best of our knowledge, this is the first report of a chondrolipoma originating as a primary tumour in the lingual frenulum of a dog.

Cutaneous Angiolymphoid Hyperplasia in a Dog.

A 5-year-old male miniature dachshund was presented with a dermal nodule on the left forelimb that increased to 5 mm in diameter over a 2-month period. Grossly, the nodule was firm, and both the external and cut surfaces were homogeneously pale pink in colour. Microscopically, the nodule was comprised of mainly plump endothelial cells and inflammatory cells; among the latter, lymphocytes were predominant, with few scattered plasma cells, mast cells and macrophages. Lymphoid follicles with germinal centres were often observed. Mitotic figures were not observed amongst the endothelial cells. Immunohistochemically, the endothelial cells were positive for vimentin, factor VIII-related antigen and CD31, and the surrounding cells were positive for smooth muscle actin. Lymphocytes expressed CD3 or BLA36. These findings led to a diagnosis of cutaneous angiolymphoid hyperplasia. To the best of our knowledge, this is the first report of a cutaneous proliferative disorder comprising an admixture of proliferating vascular endothelial cells and lymphocytic infiltration with follicle formation in a dog.

The canine prostate cancer cell line CHP-1 shows over-expression of the co-chaperone small glutamine-rich tetratricopeptide repeat-containing protein α.

Although androgen therapy resistance and poor clinical outcomes are seen in most canine prostate cancer cases, there are only a few tools for analysing canine prostate cancer by using a cell biological approach. Therefore, to evaluate androgen-independent neoplastic cell growth, a new canine prostate cancer cell line (CHP-1) was established in this study. CHP-1 over-expressed the co-chaperone small glutamine-rich tetratricopeptide repeat-containing protein α (SGTA), which is over-expressed in human androgen-independent prostate cancer. The CHP-1 xenograft also showed SGTA over-expression. Although CHP-1 shows poor androgen receptor (AR) signalling upon dihydrotestosterone stimulation, forced expression of AR enabled evaluation of AR signalling. Taken together, these results suggest that CHP-1 will be a useful model for investigating the pathogenesis of androgen-dependent and androgen-independent canine prostate cancer.

Malignant Oestrogen-producing Teratoma in a Cat.

A 5-year-old female domestic shorthair cat was presented with abdominal distension and serum biochemical evaluation indicated a high concentration of oestradiol (32.81 pg/ml). Exploratory laparotomy revealed a large cystic mass in the right ovary with cystic fluid containing a high level of oestradiol (18.80 pg/ml). The tumour was composed of immature neuroectodermal tissue, mature cartilage, smooth muscle, adipose tissue and aggregated, poorly differentiated mesenchymal cells. It contained cysts of various sizes that were lined by epithelium of different types. The basal layer of the lining epithelium was shown to express aromatase by immunohistochemistry. The findings suggest that this was a novel, malignant, oestrogen-secreting teratoma and that the aromatase-positive, neoplastic cells may have been the source of elevated levels of serum oestrogen.

Properties of the feline tumour suppressor reduced expression in immortalized cells (REIC/Dkk-3).

Reduced expression in immortalized cells (REIC/Dkk-3), a member of the human Dickkopf (Dkk) family, is a growth suppressor in human and canine mammary tumours. Mammary gland tumours are common neoplasms with high malignancy in female cats. The purpose of this study was to clone the feline REIC/Dkk-3 homolog, investigate its expression in cell lines established from feline mammary gland tumours, and test its tumour suppressor function. Western blot analysis revealed that expression of the REIC/Dkk-3 protein was reduced in feline mammary carcinoma cell lines. Forced expression of REIC/Dkk-3 induced apoptosis in feline mammary tumour cell lines. These results demonstrate that REIC/Dkk-3 expression, which is downregulated in feline mammary tumour cell lines, results in the induction of apoptosis in these cells. Our findings suggest that feline REIC/Dkk-3 represents a potential molecular target for the development of therapies against feline mammary cancers.

Denervation-Associated Change in the Palatinus and Levator Veli Palatini Muscles of Dogs with Elongated Soft Palate.

Muscle lesions and decreased numbers of peripheral nerve branches have been reported in the soft palates of dogs presenting with brachycephalic airway obstruction syndrome (BAOS). Myosin adenosine triphosphatase staining was employed to investigate whether muscle lesions in the elongated soft palate (ESP) of dogs with BAOS reflect the presence of denervation. Soft palates were collected from nine brachycephalic dogs during surgical intervention for BAOS and from five healthy beagle dogs as controls. In the control soft palates, myofibres with relatively uniform diameters and a random mosaic pattern of type I and II myofibres were observed in the palatinus muscle (PM), while almost all of the myofibres in the levator veli palatini muscle (LVPM) were of type II. In the ESPs, small group atrophy, large group atrophy and angular-shaped atrophy were observed in myofibres of the PM and rarely in the LVPM. Fibre type grouping and an increase in type IIC myofibres were found only in the PM. Morphometric analysis of ESPs revealed a significant increase in the number of type I and II myofibres in the PM showing atrophy or hypertrophy compared with controls. A significant increase in atrophic type II myofibres was found in the LVPM of affected dogs. Myopathy consistent with denervation was observed in the PM, but rarely in the LVPM, of ESP specimens. The results suggest that the myopathy seen in dogs with ESP may partly reflect atrophy of myofibres resulting from damage to peripheral nerve branches, with subsequent reinnervation of myofibres.

Salivary Gland Epithelial-Myoepithelial Carcinoma with High-Grade Transformation in a Dog.

An 8-year-old male neutered standard dachshund was presented with a slowly growing mass in the left submandibular salivary gland. Histopathological examination revealed a tumour that was composed of bilayered duct-like structures with an inner layer of ductal cells and an outer layer of clear cells. Both inner and outer cells in the greater part of the tumour exhibited low to moderate atypia and low mitotic activity. However, a focal area towards the periphery showed enhanced cellular atypia and mitotic activity in tumour cells. Immunohistochemically, the outer layer of clear cells expressed myoepithelial markers, while the inner layer cells were positive for a luminal epithelial marker. No local recurrence or lymph node or distant metastasis was observed 18 months following surgery. Based on the morphology and immunohistochemical findings, a final diagnosis of epithelial-myoepithelial carcinoma with high-grade transformation was made.

Characterization of Spontaneous Mammary Tumors in Domestic Djungarian Hamsters (Phodopus sungorus).

Mammary tumors that spontaneously occurred in domestic Djungarian hamsters (Phodopus sungorus) were histologically examined. Forty-five mammary tumors included 14 adenomas, 18 adenocarcinomas, 1 lipid-rich carcinoma, 2 adenoacanthomas, 2 malignant adenomyoepitheliomas, 1 benign mixed tumor, and 7 "balloon cell" carcinosarcomas. The latter 4 types were newly recognized neoplasms in Djungarian hamsters. The relatively high incidence of spontaneous mammary carcinosarcomas in domestic Djungarian hamsters is intriguing. Carcinosarcomas exhibited anomalous histological features made up of a mixture of glandular cells, polygonal cells (including "balloon cells"), and sarcomatous spindle cells in varying proportions. Transitional features from glandular cells to polygonal cells and subsequently to sarcomatous spindle cells were observed. Using immunohistochemistry, we observed that glandular cells exhibited an epithelial phenotype (cytokeratin(+)/vimentin(-)), spindle cells exhibited a mesenchymal phenotype (cytokeratin(-)/vimentin(+)), and polygonal cells exhibited an intermediate phenotype (cytokeratin(+)/vimentin(+)). Reduction or loss of ß-catenin expression and gain of S100A4 expression were observed in polygonal and spindle cells. The polygonal cell population included a varying number of characteristic cells that were expanded by large intracytoplasmic vacuoles. Electron microscopy revealed that these "balloon cells" had large cytoplasmic lumens lined by microvilli. These observations suggest that epithelial-mesenchymal transition may account for the pathogenesis of mammary carcinosarcomas in Djungarian hamsters.

Phenotypic screening of a library of compounds against metastatic and non-metastatic clones of a canine mammary gland tumour cell line.

Metastases are associated with a poor prognosis for canine mammary gland tumours (CMGTs). Metastatic and non-metastatic clones were isolated previously from a single malignant CMGT cell line. The difference in metastatic potential between the two cell lines was hypothesised to be associated with distinct cellular signalling. The aim of this study was to screen for compounds that specifically target metastatic cells in order to improve CMGT therapeutic outcomes. The two clonal cell lines were characterised by transcriptome analysis and their sensitivity to a library of 291 different compounds was compared. The metastatic clone exhibited elevated expression of molecules associated with degradation of the extracellular matrix, epithelial-mesenchymal transition and cancer stem cell phenotype. This was confirmed using a matrigel invasion assay and by assessment of aldehyde dehydrogenase activity. The mitochondrial respiratory chain complex inhibitors (MRCIs; rotenone, antimycin and oligomycin) significantly inhibited the growth of the metastatic clone. Although MRCIs similarly depleted mitochondrial ATP in both clones, the subsequent cellular response was different, with toxicity to the metastatic clone being independent of AMP-activated protein kinase activity. The results of this study suggest a potential utility of MRCIs as anti-tumour agents against metastatic CMGTs. Further studies are needed to investigate the clinical utility of MRCIs and to determine the association between MRCI sensitivity and malignancy.

Neuroendocrine carcinoma of the mammary gland in a dog.

A 10-year-old female border collie was presented with a mass (2 cm diameter) in the fifth mammary gland. The mass was located in the subcutis and the cut surface was grey-white in colour. Microscopically, the mass was composed of tumour cells arranged in nests of various sizes separated by delicate fibrovascular stroma. The tumour cells had small, round hypochromatic nuclei and abundant cytoplasm. Metastases were observed in the inguinal lymph node. Immunohistochemically, most tumour cells expressed cytokeratin (CK) 20, chromogranin A, neuron-specific enolase, synaptophysin and oestrogen receptor-ß, but not low molecular weight CK (CAM5.2), p63 and insulin. Ultrastructurally, the tumour cells contained a large number of electron-dense granules corresponding to neuroendocrine granules. Based on these findings, this case was diagnosed as a neuroendocrine carcinoma of the mammary gland.

Cellular sources of tenascin-C in canine mammary carcinomas.

Tenascin-C (Tn-C) is an extracellular matrix glycoprotein implicated in the progression of several human cancers. In canine mammary carcinomas, accumulation of Tn-C has been recognized in 3 different areas: regions of proliferating myoepithelial cells in complex carcinoma, basement membrane zone in low-grade simple carcinoma, and reactive stroma in high-grade simple carcinoma. To identify the Tn-C synthesizing cells in these areas, we utilized double-labeling immunohistochemistry, branched DNA in situ hybridization, and in situ hybridization-immunohistochemistry double-labeling techniques. In complex carcinomas, Tn-C was generated by proliferating myoepithelial cells. Tn-C in low-grade simple carcinomas was also derived from myoepithelial cells existing as a basal monolayer. However, stromal Tn-C in high-grade carcinomas was mainly synthesized by fibroblasts/myofibroblasts, similar to human breast cancer. Thus, the origin of Tn-C in canine mammary carcinomas differs between low- and high-grade malignancies. The role of myoepithelial cell-generated Tn-C is not yet understood.

Differences in indicators of malignancy between luminal epithelial cell type and myoepithelial cell type of simple solid carcinoma in the canine mammary gland.

Routinely diagnosed simple solid carcinoma (SSC) of the canine mammary gland comprises a heterogeneous group of tumors. Seventy-two cases that had been diagnosed as SSC based on hematoxylin and eosin-stained tissue sections were reclassified immunohistochemically on the basis of myoepithelial markers p63 and α-smooth muscle actin, as well as a luminal epithelial marker cytokeratin 8. Only 23 cases (32%) were true SSC, composed only of luminal epithelial cells, whereas 11 cases (15%) were malignant myoepithelioma (MM), composed predominantly of myoepithelial cells, and 38 cases (53%) were biphasic carcinoma (BC), characterized by biphasic proliferation of luminal epithelial and basal/myoepithelial components. As the pathological parameters were compared between the reclassified tumor types, infiltrative potential, vascular/lymphatic invasion, lymph node metastasis, and Ki-67 labeling index were higher in true SSC compared with MM and BC, suggesting that the former may exhibit a poorer prognosis compared with the latter two.

Acinar cell cystadenoma of the pancreas in a cat.

Cystic tumours of the pancreas are heterogeneous lesions with a spectrum of morphology and biological behaviour in people. These are poorly characterized in animals. A multicystic tumour of the pancreas was identified in an 11-year-old, female, mixed breed cat. The tumour was 5.5 cm in diameter and the largest cysts were 1.5 cm in diameter. Microscopically, the cysts were lined by single layered or pseudostratified, flat, cuboidal or columnar epithelial cells that occasionally formed papillary structures with a thin fibrous core. The tumour cells had eosinophilic granules in the apical cytoplasm, similar to zymogen granules, and the nuclei were uniform in size and shape. Mitotic figures were not observed. Immunohistochemically, the tumour cells expressed trypsin, but not cytokeratin 7. A diagnosis of acinar cell cystadenoma of the pancreas was made and this is the first report of this tumour in a cat.

Multiple inflammatory gastric polyps treated by endoscopic polypectomy with argon plasma coagulation in a dog.

An 11-year-old spayed female miniature dachshund was evaluated for a 2-month history of chronic vomiting. Abdominal ultrasonography revealed a heterogeneous mass in the pyloric region. Contrast upper gastrointestinal radiography demonstrated impairment of gastric outflow. Endoscopic examination revealed multiple polyps at the gastric pylorus. The pyloric polyps were variable in size, sessile-shaped and pedunculated. Initially, endoscopic polypectomy was attempted, but all the polyps could not be completely resected. Thus, endoscopic polypectomy with argon plasma coagulation was performed to cauterise the lesions. The histopathological diagnosis of the lesions was inflammatory polyps, and a moderate number of Helicobacter spp. was revealed. After the argon plasma coagulation treatment, the dog did not vomit, and improvement of clinical signs was maintained for 13 months. Endoscopic polypectomy with argon plasma coagulation may be useful for mixtures of sessile and pedunculated polyps. The present report may provide a basis for further studies of argon plasma coagulation treatment for canine gastrointestinal polyps.

Aldehyde dehydrogenase activity in cancer stem cells from canine mammary carcinoma cell lines.

Increasing evidence suggests that diverse solid tumours arise from a small population of cells known as cancer stem cells or tumour-initiating cells. Cancer stem cells in several solid tumours are enriched for aldehyde dehydrogenase (ALDH) activity. High levels of ALDH activity (ALDH(high)) were detected in four cell lines derived from canine mammary carcinomas. ALDH(high) cells were enriched in a CD44(+)CD24(-) population having self-renewal capacity. Xenotransplantation into immunodeficient mice demonstrated that 1×10(4) ALDH(high) cells were sufficient for tumour formation in all injected mice, whereas 1×10(4) ALDH(low) cells failed to initiate any tumours. ALDH(high)-derived tumours contained both ALDH(+) and ALDH(-) cells, indicating that these cells had cancer stem cell-like properties.

Increased presence of stromal myofibroblasts and tenascin-C with malignant progression in canine mammary tumors.

The aims of this study were to determine whether the appearance of stromal myofibroblasts and the expression of tenascin-C (Tn-C) correlate with the grade of malignancy in canine mammary tumors and to determine the main cellular source of Tn-C in these tumors. Single or double immunostaining using antibodies against α-smooth muscle actin (α-SMA) and Tn-C was performed on serial sections of normal canine mammary glands as well as those with lobular hyperplasia, simple adenoma, and simple carcinoma. Thirty-nine of 42 simple carcinomas (93%) exhibited stromal α-SMA-positive myofibroblasts and Tn-C expression. Only 6 of 11 cases of simple adenoma (55%) showed these changes, whereas no changes were observed in normal mammary gland tissue or cases of lobular hyperplasia. The distribution of stromal Tn-C correlated with the presence of myofibroblasts. However, Tn-C immunoreactivity was also occasionally observed in the basement membrane zone surrounding the myoepithelial layer in normal tissue, benign lesions, and tubulopapillary carcinomas. This pattern of staining was not related to the presence of myofibroblasts. The appearance of stromal myofibroblasts and expression of Tn-C were significantly correlated with higher histological grades of malignancy and vascular/lymphatic invasion in simple carcinomas. Stromal myofibroblasts appear to be a major cellular source of Tn-C and play an important role in the development of canine mammary tumors. The Tn-C expressed in the basement membrane zone of normal, hyperplastic, and neoplastic mammary tissue, which is likely produced by neighboring myoepithelial cells, may differ functionally from the Tn-C produced by myofibroblasts.