Histopathological features of canine spontaneous non-neoplastic gastric polyps - a retrospective study of 15 cases.

Fifteen cases of canine gastric polyps, collected over a 4-year period, were investigated using gross inspection, histological procedures and immunohistochemical techniques for Helicobacter infection. No breed or sex predisposition was found for gastric polyps, although they occurred mainly in elderly animals. There were 9 pedunculated and 6 sessile polypoid growths, between 5 to 30 mm in diameter developed mainly in the pyloric region of the stomach. The most common type of gastric polyps was the hyperplastic one. The inflammatory type was identified in three cases. Foci of AB/PAS Goblet positive cells resembling intestinal metaplasia, mild dysplasia of gastric epithelium, well delimited calcified areas, islands of osteoid matrix and nematodes were present in some of these lesions. Histological examination of the adjacent gastric polyp (surrounding gastric mucosa) revealed a severe chronic inflammation in 13 cases and a high grade of Helicobacter species colonization in all cases, but Kendall test analysis showed no correlation between Helicobacter spp. colonization degree and gastritis scores (τ = 0289; p = 0.204). A significant correlation was found between Helicobacter spp. location and gastritis scores (τ = 0.497; p = 0.035). Immunohistochemistry performed with a polyclonal antibody confirmed Helicobacter spp. infection in all cases. Based on their morphology, Helicobacter pylori - like organisms were described in 3 of 15 cases. No high degree of dysplasia nor neoplasia were identified in these lesions. The etiology and pathogenesis of gastric polyps in dogs are still unknown, although a severe chronic antral gastritis may be a predisposing condition for development of gastric polyps in dogs.

Lymphadenopathy associated with a thyroid carcinoma in a dog.

Angiomatoid lesions in a lymph node associated with a thyroid carcinoma of a dog were restricted to the subcapsular and medullary sinuses. Lymphoid atrophy was present, but nodal architecture was not distorted and normal structures were not invaded. Immunohistochemical staining indicated that the vascular spaces formed by spindloid cells were lined by endothelium with a low mitotic index. The spindloid cells were positive for smooth muscle actin, vimentin, and desmin and thus were likely to be fibroblasts, myofibroblasts, smooth muscle cells, and/or pericytes. These features are comparable to vascular transformation of lymph node sinuses in humans (nodal angiomatosis), a nonneoplastic condition often associated with mechanical or functional blockage of efferent lymphatics and veins.

Cutaneous schwannomas in 22 horses.

Schwannomas are uncommonly recognized in horses. This study describes cutaneous schwannomas in 22 horses aged 8 to 25 years: 12 male, 7 female, and 3 of unknown sex. The horses had solitary cutaneous masses: 9 on the head, 3 on the neck, and the others on the shoulder, hip, thorax, abdomen, rump, extremities, or tail. The location of 1 tumor was unknown. The dermal tumors were well demarcated and expansile. Twelve had a multinodular pattern, whereas 10 formed a single nodule. Antoni A areas were observed in all tumors, and 10 tumors contained Antoni B areas. In Antoni A areas, the densely packed spindle-shaped neoplastic cells were arranged in short fascicles with nuclear palisading. In the hypocellular Antoni B areas, neoplastic cells were separated by abundant myxomatous stroma. Tumors commonly had hyalinization of stroma and vessel walls and ancient change. Cellular vacuolation was observed in 18 tumors. In all 22 cases, neoplastic cells were immunopositive for S100 protein. Expression of laminin and glial fibrillary acidic protein was observed in all 6 tumors evaluated by immunohistochemistry for these markers. One tumor was examined ultrastructurally: Neoplastic cells had branched cytoplasmic processes and were surrounded by an external lamina. Follow-up information was available 8 months to 10 years postexcision for 9 horses, for which surgical excision of the tumor was curative. The equine cutaneous schwannomas in this study had microscopic features like those of human schwannoma and had benign clinical behavior. Correct classification of equine cutaneous schwannoma will facilitate accurate prognosis and appropriate treatment.

Malignant round cell neoplasia in llamas and alpacas.

Malignant round cell neoplasia was identified in 12 llamas and 12 alpacas aged 0-23 years. Mean age of affected alpacas (3.1 years) was significantly less than that of affected llamas (8.0 years). Tumor cell morphology varied from large and often pleomorphic (11 tumors) to small and often homogeneous (13 tumors). Neoplastic lesions were multicentric in 12 cases. Other sites were gastric (5 cases), intra-abdominal (perirenal; 4 cases), intrathoracic (2 cases), and cervical (1 case). Immunohistochemistry with antibodies to CD79alpha, BLA36, and CD3 identified B-cell lymphoma (12 cases) and T-cell lymphoma (6 cases). Six tumors did not express any lymphoid marker and were further immunostained for neuron-specific enolase (NSE), synaptophysin, S-100, glial fibrillary acidic protein (GFAP), and chromogranin A. All 6 of these tumors were negative for GFAP and chromogranin A but expressed 1 or more of the neural markers NSE, synaptophysin, and S-100 and were classified as primitive malignant round cell tumors (PMRCT). Tumor types could not be distinguished on the basis of animal age, gross pathologic appearance, tumor morphology, or tumor location. All animals with lymphoma and 5 with PMRCT died or were euthanatized. One alpaca with a focal cervical PMRCT lived for at least 20 months after diagnosis. Results of this study indicate that malignant round cell tumors in llamas and alpacas are a heterogeneous group that cannot be distinguished on the basis of signalment, postmortem findings, or routine light microscopic findings. Immunohistochemistry is a valuable diagnostic procedure when evaluating malignant round cell neoplasia in llamas and alpacas.

Gastric adenocarcinoma in a horse with portal vein metastasis and thrombosis: a novel cause of hepatic encephalopathy.

A 17-year-old Quarter horse mare was referred to Cornell University for postmortem examination after 72 hours of encephalopathy that consisted of depression, mania, and blindness. A plasma sample and cerebral spinal fluid demonstrated hyperammonemia. Gross necropsy examination findings included the following: mild icterus, a transmural mass in the glandular portion of the gastric fundus, multiple masses throughout the liver, and a large tumor thrombus in the portal vein. Microscopically, the gastric mass, hepatic masses, and portal vein thrombus were composed of similar neoplastic epithelial cells that formed variably sized acini and branching cords separated by a dense desmoplastic stroma. Throughout the cerebral frontal cortex were numerous Alzheimer type II astrocytes. Hepatic encephalopathy was caused by gastric adenocarcinoma, with metastasis to the liver and the portal vein. The clinical and pathologic lesions from this unique case, as well as hyperammonemia and portal vein thrombosis in the pathogenesis of hepatic encephalopathy, are discussed.

Ubiquitin expression in muscle from horses with polysaccharide storage myopathy.

Serial sections of formalin-fixed, paraffin-embedded muscle biopsy specimens from 28 Quarter Horse, Paint, and draft-related breeds, aged 0.5-23 years, were treated with periodic acid-Schiff (PAS) stain for glycogen and were immunostained to detect ubiquitin expression. On the basis of findings in PAS-stained sections, a diagnosis of equine polysaccharide storage myopathy (EPSSM) was made in 22 horses aged 2-23 years (mean, 9.4 years); samples from 6 horses aged 0.5-15 years (mean, 7.3 years) had a normal PAS staining pattern, with no relevant lesions. Ubiquitin expression was detected in all but a 2-year-old EPSSM-affected horse and was not detected in the non-EPSSM-affected horses. Ubiquitin expression was greater than the degree of PAS-positive, amylase-resistant material, and ubiquitin was detected in aggregates of amylase-sensitive glycogen as well as in aggregates of amylase-resistant material. Results suggest that glycogen aggregates develop and are ubiquitinated prior to development of amylase-resistant inclusions. Ubiquitin immunostaining may be most useful for confirming the diagnosis of EPSSM in horses with only amylase-sensitive glycogen aggregates and in horses with early amylase-resistant inclusions. However, ubiquitin immunostaining is no more sensitive than is PAS staining for diagnosis of EPSSM.

B-cell leukemia in a sheep.

Necropsy examination was performed on an 8.5-year-old Finnish ewe euthanatized because of progressive respiratory distress, cachexia, and weakness. Significant postmortem findings included a diffusely enlarged, dark-red friable liver, mild splenomegaly, and mild mesenteric lymphadenopathy. Examination of multiple tissue sections revealed intravascular atypical mononuclear cells in all tissues examined, with a leukemic pattern of infiltration of mesenteric lymph nodes, liver, lung, and spleen. Neoplastic cells were positive for CD79a and negative for CD-3, BLA.36, and CD68 leukocytic markers. The final diagnosis was B-cell leukemia.

Clinicopathological and immunophenotypical features of canine intravascular lymphoma (malignant angioendotheliomatosis).

Intravascular lymphoma (IVL) is a rare angiotropic large-cell lymphoma in which neoplastic lymphocytes proliferate within the lumina of blood vessels in the absence of a primary extravascular mass or leukaemia. A retrospective review of veterinary medical records identified 17 cases of canine IVL. Spinal cord ataxia (seven dogs), posterior paralysis (one dog), seizures (four dogs) and vestibular disease (three dogs) dominated the clinical presentation. Haemorrhage, ischaemia, and occasional foci of vascular proliferation were found in tissue sections from affected dogs. Vessels, predominantly veins, throughout the body were frequently filled with neoplastic lymphocytes. Splenic involvement occurred in only one of 10 cases examined and bone marrow involvement was absent in four cases examined. Formalin-fixed paraffin wax-embedded tissues from 15 cases were examined immunohistochemically with streptavidin-biotin-horseradish peroxidase and a catalysed signal amplification system. The neoplastic cells were classified in eight cases as T cells (CD3+/IgG-/CD79a-), in one case as B cells (CD3-/CD79a.dim/IgG+), and in the remaining six cases as non-T, non-B (CD3-/IgG-/CD79a-). The clinical and pathological features of canine IVL closely resembled those of the human disease. In striking contrast to human cases, which are most often B-cell lymphomas, the immunophenotypes of the canine IVLs in this series were heterogeneous. The canine IVLs were derived primarily from T cells and non-T, non-B lymphocytes, B cells being found in only a single instance.

Cutaneous vasoproliferative lesions in goats.

Abstract. In a retrospective survey of caprine neoplastic disease, eight masses were diagnosed as cutaneous vascular tumors. The typical clinical presentation was a solitary raised, bleeding mass. No predilection with regard to age, breed, sex, or anatomic location was found. Reevaluation of the microscopic features of the masses resulted in diagnoses of hamartoma (2), hemangioma (4), and hemangiosarcoma (2). An endothelial cell origin was confirmed in all seven tumors tested immunohistochemically for factor VIII-related antigen. Although rarely reported, goats display a range of cutaneous vascular growth abnormalities similar to those observed in other domestic animals.

Complex polysaccharide inclusions in skeletal muscle adjacent to sarcomas in two dogs.

Inclusions of periodic acid-Schiff-positive, amylase resistant material were found within skeletal muscle fibers adjacent to an osteosarcoma in the proximal femur of an 8-year-old intact female Cocker Spaniel dog (dog No. 1) and adjacent to a synovial cell sarcoma of the stifle joint in a 7-year-old spayed female Bouvier des Flandres dog (dog No. 2). Inclusions were pale blue-gray with hematoxylin and eosin stain and formed irregular inclusions, replacing up to approximately 80% of the fiber diameter. Inclusions from dog No. 2 were of non-membrane-bound granular to filamentous material that occasionally formed discrete, elongate electron-dense masses. The features of these inclusions were similar to those of materials previously described as complex polysaccharide, polyglucosan bodies, amylopectin, and Lafora bodies. Evidence for a generalized metabolic disorder was not found in these two dogs, suggesting that storage of complex polysaccharide can occur as a relatively nonspecific response to metabolic alterations in skeletal muscle in a variety of conditions.

Congenital hypotrichosis in a Percheron draught horse.

A blue roan Percheron foal was born with poorly circumscribed patchy alopecia of the trunk and legs. Teeth and hoof development were normal. Alopecia was progressive, becoming almost complete by 1 year of age. Histopathological findings in a skin biopsy obtained at 7 months of age were consistent with severe follicular hypoplasia. Sebaceous glands, epitrichial sweat glands and arrector pilae muscles were normal. The horse is alive and otherwise well at 6 years of age, although adult stature is considered small for this breed. The clinical history and histopathological findings are most consistent with a form of congenital hypotrichosis.

Pulmonary lymphomatoid granulomatosis in a cat.

Pulmonary lymphomatoid granulomatosis was diagnosed in a 9-year-old castrated male domestic shorthair cat with a history of coughing, lethargy, and anorexia. Radiographic examination revealed multiple pulmonary opacities, consolidation of left lung lobes, and enlarged tracheobronchial lymph nodes. Cytologic examination of impression smears of abnormal pulmonary tissue revealed erythrocytes, lymphocytes, and macrophages, with scattered atypical lymphocytes and binucleate cells. Histopathologic evaluation of abnormal lung tissue revealed multiple, coalescing, densely cellular nodules composed of anaplastic and pleomorphic lymphocytes, with scattered binucleate and multinucleate cells. Marked infiltration and effacement of bronchiolar and vascular smooth muscle were present. These features are characteristic of lymphomatoid granulomatosis. To the authors' knowledge, this is the first report of pulmonary lymphomatoid granulomatosis in a cat.

Caprine genital leiomyosarcoma.

An aged Saanen doe was euthanized following repeated severe hemorrhage from the vulva. Necropsy examination revealed mural thickening of tubular genitalia with firm, protruding intralumenal masses containing blood-filled cavitations, and effacement of normal cervical architecture. Histologically, uterine and cervical masses comprised a variably dense population of mildly pleomorphic spindle cells forming interlacing streams supported by variably dense collagenous stroma. Immunoperoxidase staining of neoplastic cells was positive for muscle-specific actin, supporting the diagnosis of low-grade leiomyosarcoma. Months later, the doe's twin was likewise euthanized due to persistent bleeding from the vulva associated with a large vulvar mass having histopathologic features similar to those of the previous case. The clinical, gross, and histologic findings are similar to five cases of caprine genital leiomyosarcoma identified in retrospectively analyzed case material. Analysis of caprine tumor accessions over 20 years demonstrated a significantly higher incidence of genital leiomyosarcoma within the Saanen breed.

Dermal intravascular leiomyosarcoma in a cat.

A 10-year-old female spayed domestic shorthaired cat presented with a subcutaneous tumor between the first and second phalanges of the left hind foot. Six months after excision, a similar tumor occurred on the medial aspect of the third phalanx of the same limb. Histologically, both tumors consisted of solid masses of spindle and round cells, many of which grew within endothelial-lined vessels. Tumor cells stained positively for smooth muscle actin and vimentin, but were negative for cytokeratin, S-100, desmin, synaptophysin, factor VIII-related antigen, and neuron-specific enolase. The diagnosis was dermal intravascular leiomyosarcoma.

Gastric function in dogs with naturally acquired gastric Helicobacter spp. infection.

The association of Helicobacter pylori with gastritis, peptic ulcers, and gastric neoplasia has led to fundamental changes in the understanding of gastric disease in humans. The relationship of Helicobacter spp. infection to gastric disease in dogs is unclear. The objective of this study was to determine if Helicobacter infection affects the gastric secretory axis of dogs. Eight Beagle dogs with naturally acquired Helicobacter spp. infection were studied before and after (4 and 29 days) the attempted eradication of Helicobacter spp. with a combination of amoxicillin, metronidazole, and famotidine (AMF). Six specific-pathogen-free, Helicobacter-free Beagle dogs served as controls. The electron microscopic appearance of spiral organisms in infected dogs indicated coinfection with Helicobacter felis- and H bizzozeronii-like organisms. Unstimulated gastric pH and fasting, postprandial, and bombesin-stimulated plasma gastrin were similar in both infected and uninfected dogs, although a trend (P = .09) toward higher meal-stimulated gastrin was observed in infected dogs at 60 minutes. Pentagastrin-stimulated maximal acid output (mmol HCI/kg0.75/hour) and titratable acidity (mmol HCl/mL) were similar in both infected and uninfected dogs, but gastric pH during maximal acid output was lower (P < .01) in uninfected dogs. Mild gastric inflammation was present in both infected and uninfected dogs. Gastric spiral organisms were undetectable in 6/8 infected dogs 4 days after AMF but had recurred in 8/8 dogs 29 days after AMF. Analysis of gastric DNA with Helicobacter-specific primers indicated persistence of Helicobacter DNA at 4 and 29 days after antibiotic therapy. Acid secretion, plasma gastrin, and mucosal inflammation were not affected by the transient suppression of Helicobacter spp. by AMF. These findings suggest that gastric secretory function in dogs is not markedly perturbed by naturally acquired Helicobacter spp. infection and that treatment with amoxicillin, metronidazole, and famotidine causes suppression rather than eradication of gastric Helicobacter spp. in dogs.

Intramuscular desmoid tumor (musculoaponeurotic fibromatosis) in two horses.

Intramuscular desmoid tumors (musculoaponeurotic fibromatosis) were discovered in two young adult horses. The tumor in one horse was in the lateral cervical musculature, and that in the second horse occurred in the pectoral musculature. Histopathologic features were similar in both horses and included proliferation of fibroblasts and cells expressing muscle actin (myofibroblasts), with extensive dissecting fibrosis within muscle. These features are similar to those of desmoid tumors in humans, particularly those also known as musculoaponeurotic fibromatosis. Dissection of these lesions revealed a single central (horse No. 1) or multiple central (horse No. 2) fluid-filled cavities with associated sterile inflammation. The presence of these cavities supports the hypothesis that equine desmoid tumors are traumatic in origin, possibly occurring at sites of injections or bursal rupture. Surgical excision of the tumor in horse No. 1 was apparently curative, but the extent of the tumor in horse No. 2 precluded surgical excision.

Helicobacter felis infection in dogs: effect on gastric structure and function.

The relationship of Helicobacter felis, an organism that is observed in the stomachs of dogs, to gastric disease in dogs is unclear. The objective of this study was to determine if Helicobacter felis infection alters gastric morphology and gastric secretory function in dogs. Five specific-pathogen-free (SPF), Helicobacter-free Beagle dogs were examined before and for 26 weeks after inoculation with H. felis (ATCC 49179). Three SPF uninfected dogs served as controls. All five dogs became colonized by H. felis as determined by urease activity, histopathology, polymerase chain reaction, and transmission electron microscopic examination of serial gastric biopsies. The degree of colonization ranged from < 1 organism/400 x field to > 10 organisms/400 x field. The fundus, body, and cardia were most heavily colonized. Evaluation of gastric biopsies showed mild gastric inflammation and lymphoid follicles in both infected and uninfected dogs. There was no correlation between the number of organisms observed and the degree of gastric inflammation or number of lymphoid follicles. The gastric secretory axis, assessed by fasting and meal-stimulated plasma gastrin, mucosal gastrin and somatostatin immunoreactivity, fasting gastric pH, and pentagastrin-stimulated gastric acid secretion, was similar in both infected and uninfected dogs. Fasting gastric pH was not a reliable indicator of gastric secretory function. These findings suggest that H. felis may not be a gastric pathogen in dogs. However, the density of colonization and limited duration of infection should be considered when interpreting these findings.

Acute lymphocytic infiltration in an extremely early lesion of fibrodysplasia ossificans progressiva.

A 2-year-old child with fibrodysplasia ossificans progressiva underwent a muscle biopsy of a very early lesion, and had findings that showed the earliest stage ever seen in the histopathology of fibrodysplasia ossificans progressiva. This very early stage consisted of intense perivascular lymphocytic infiltration into normal appearing skeletal muscle. A nearly identical histopathologic sequence was noted in a cat with phenotypic features similar to those of fibrodysplasia ossificans progressiva in humans. These new findings represent the earliest documented changes that have ever been noted in fibrodysplasia ossificans progressiva, and provide further histopathologic support for the recent discovery that lymphocytes may play a role in the pathogenesis of heterotopic ossification in fibrodysplasia ossificans progressiva.

Dietary control of exertional rhabdomyolysis in horses.

OBJECTIVE: To determine whether feeding a low-carbohydrate, high-fat diet would decrease severity of exercise-induced muscle injury in horses with exertional rhabdomyolysis. ANIMALS: 19 horses with a history of exertional rhabdomyolysis. DESIGN: Case series. PROCEDURE: Specimens of the semitendinosus or semimembranosus muscle were obtained for histologic examination, and serum creatine kinase (CK) and aspartate transaminase (AST) activities 4 hours after exercise were determined. Horses were then fed a low-carbohydrate, high-fat diet, and serum CK and AST activities 4 hours after exercise were reevaluated at approximately monthly intervals for 3 to 6 months. RESULTS: Serum CK and AST activities 4 hours after exercise were high before any change in diet. All 19 horses had evidence of chronic myopathic change and abnormal glycogen accumulation in muscle biopsy specimens; 11 horses also had evidence of complex polysaccharide accumulation. Adaptation to diet change required approximately 3 to 6 months. Sixteen horses did not have any episodes of exertional rhabdomyolysis after 3 to 6 months of diet change, and 3 horses had mild episodes of exertional rhabdomyolysis following either a reduction in dietary fat intake or restriction in exercise. Postexercise serum CK and AST activities 3 to 6 months after the change in diet were significantly less than initial values. CLINICAL IMPLICATIONS: Results indicated that exertional rhabdomyolysis may be a result of abnormal carbohydrate metabolism in some horses. Feeding a diet with low carbohydrate and high fat content may reduce severity of exercise-induced injury in some horses with exertional rhabdomyolysis.