Visceral leishmaniasis in a dog: clinical, hematological and pathological observations.

Visceral leishmaniasis was diagnosed in a dog that had been living with his owners in Spain for two years. Clinical diagnosis was somewhat delayed as the disease is largely unknown to Canada and was manifested by a nonresponsive anemia which was not easily explained on peripheral blood evaluation alone, and concomitant interstitial nephritis. On post mortem examination splenomegaly was the main gross pathological finding. Light microscopic examination of bone marrow aspirates and subsequent electron microscopic examination of splenic and hepatic tissues revealed numerous Leishman-Donovan bodies in cells of the reticuloendothelial system. Parasitized reticuloendothelial cells were seen singly or forming granulomata. These latter did not contain giant cells and were confined mainly to the liver and spleen, being sparse and single in the first but extremely numerous and coalescing in the latter. Accumulation of intrafollicular hyaline material was seen in a small number of splenic follicles. Leishman-Donovan bodies on electron microscopic examination had a trilaminar periplast, a large round nucleus with heavy blocks of marginated chromatin and two nucleoli, a short flagellum and a kinetoplast. Lymph nodes and bone marrow had numerous parasitized macrophages but no granulomata. Leishman-Donovan bodies were not detected in the lungs and kidneys both of which exhibited a chronic intersitital reaction. The comparative hematological profile as well as the importance of bone marrow and electron microscopic examinations of the spleen and liver in diagnosis are discussed. The potential public health hazard of leishmaniasis to North America and particularly to Canada is considered.     

Bronchiolar adenocarcinoma in a cow

An aged beef cow had a primary lung tumor that was diagnosed postmortem. Clinical signs included inappetence, weight loss, coughing, dyspnea, and reduced lung sounds. Antibiotic treatment was ineffective. The cow was euthanatized. Postmortem examination revealed numerous, firm nodules throughout both lungs. Microscopically, the pulmonary nodules contained neoplastic cells and the diagnosis was bronchiolar adenocarcinoma. A diagnosis of pulmonary neoplasia, although rare, should be considered in an aged cow with similar historical and clinical findings.     

M cells in the rectum of calves

The morphology of gut-associated lymphoid tissue and the ultrastructure of overlying lymphoepithelium of newborn and three-week-old conventionally raised calves were compared. In all calves patches of lymphoid nodules were found in the terminal rectum. In newborn calves lymphoid nodules in the submucosa with caps of lymphoid tissue in the lamina propria predominated. In three-week-old calves lymphoglandular complexes were as numerous as lymphoid nodules with caps. Scanning and transmission electron microscopical examination of superficial lymphoepithelium over caps and lymphoepithelium in epithelial diverticula of lymphoglandular complexes revealed groups or single cells morphologically resembling M cells, but with widely varying apical processes. To investigate whether these putative M cells in rectal lymphoepithelium internalise and transport macromolecules across the epithelial barrier, ferritin was injected into the rectum of three-week-old calves. Eighty to 150 minutes after exposure ferritin was detected in cells resembling M cells. Thus these cells ought to be considered as M cells. It may be hypothesised that gut-associated lymphoid tissue with specialised lymphoepithelium in the rectum of calves provides a route for the uptake of antigen.     

Epithelioid leiomyosarcoma in the visceral peritoneum of an American badger (Taxidea taxus).

A 12-year-old female American badger was presented to the Taipei city zoo veterinary ward with anorexia and weakness. Treatments were ineffective, and the badger died of chronic interstitial nephritis and uremia. At necropsy, numerous firm white nodules, measuring 0.5-2.0 cm, were present on the surface of the liver, stomach, spleen, small intestine, pancreas, and diaphragm. Most nodules were encapsulated and well demarcated from the organs to which they were attached. A poorly demarcated mass, measuring 0.5 cm in diameter, had invaded the hepatic parenchyma and appeared to be the origin of all the nodules derived by transcavitary implantation. Histologically, the nodules contained primarily oval or spindle-shaped cells, typical of smooth muscle cells, forming alternating bundles attached to the surface of the various organs. In some nodules, aggregates of individual polyhedral to round cells with round to oval centrally located nuclei and abundant eosinophilic cytoplasm, typical of smooth muscle origin, were noted. Zones of subcapsular necrosis and multifocal necrosis were also observed in some nodules. Tumor cells stained positively for alpha-smooth muscle actin and vimentin and negatively for desmin, cytokeratin, estrogen, and progesterone receptors. This tumor is similar to but distinguishable from the "disseminated peritoneal leiomyomatosis (DPL)" found in women.     

Sterile panniculitis in dogs: new diagnostic findings and alternative treatments

The objective of this study was to analyse the underlying diseases, diagnostic findings and treatment outcomes in 10 dogs with sterile panniculitis. There was no significant breed association in this study (P = 0.86).The median age of the dogs was 7.4 years. Concurrent diseases included atopic dermatitis (four dogs), acute pancreatitis (two dogs) and primary hypoadrenocorticism (one dog), with no concurrent conditions detected in three dogs. There was no significant association with the sterile panniculitis (P = 0.57). Well-circumscribed firm nodules were noted in seven dogs, and ill-defined soft nodules were observed in three dogs. Bacterial and fungal cultures of biopsy samples were negative in all cases. Fine-needle aspiration cytology of the nodules revealed pleomorphic mesenchymal cells in all of the well-circumscribed firm nodules, whereas numerous inflammatory cells and adipose cells were evident in soft nodules. These results indicate that firm nodules in panniculitis could be misdiagnosed as tumours. Immunosuppressive therapy was used in eight cases. Topical dexamethasone was used in four dogs, intralesional dexamethasone in one dog, oral prednisolone plus ciclosporin in two dogs and oral prednisolone only in one dog. The remaining treatments were surgical excision and systemic cefalexin in one dog each. The lesions regressed within 1 week in all cases, with more rapid remission following systemic immunosuppressive therapy. This study suggests that cytology may be misinterpreted as neoplastic, especially with firm lesions. In addition, topical glucocorticoid therapy should be further evaluated as a potential treatment for canine sterile panniculitis.     

Nodular thyroid hyperplasia in a cynomolgus monkey

Nodular thyroid hyperplasia was found in a 4-year-old male cynomolgus monkey (Macaca fascicularis). The monkey was clinically normal; however, necropsy revealed multiple variably sized nodules in both lobes of the thyroid gland. In contrast to the fairly uniform diameter of the lumen of follicles in the surrounding gland, the diameter of the follicular lumen within the hyperplastic nodules was highly variable and ranged from nonexistent to cystlike. Occasionally, in the larger follicles there were papillary infoldings of epithelium. The hyperplastic nodules were partially encapsulated by a fibrous capsule and showed little compression of the surrounding tissue. The follicular cells and colloid comprising the hyperplastic nodule were immunohistochemically positively stained with the antibody for thyroglobulin. Ultrastructurally, the cells forming follicles had numerous microvilli along the luminal surface, and lysosomal bodies and dilated rough endoplasmic reticulum in the cytoplasm. All these morphologic findings are consistent with nodular thyroid hyperplasia, which is rare in nonhuman primates.     

Feline mesothelioma: case report and review of cytologic,immunocytochemical, histopathologic,and immunohistochemical findings

Mesotheliomas are uncommon neoplasms that arise from mesothelial cells in either the abdominal or thoracic cavities and are rarely diagnosed in cats. A 10-y-old spayed female domestic shorthair cat was presented to the Louisiana State University oncology service for evaluation of a large amount of abdominal effusion. Abdominal ultrasound identified a large mesenteric mass with numerous ill-defined nodules. An abdominocentesis was performed with cytologic and immunocytochemical findings consistent with a neoplastic effusion, with large clusters of epithelioid cells that exhibited strong cytoplasmic expression of pancytokeratin, vimentin, and Wilms tumor 1 antigens. Further testing was declined, and meloxicam was prescribed until the cat died 23 d after initial presentation. Upon postmortem examination, the omentum was contracted into a firm mass adhered to multiple organs and accompanied by numerous small white nodules throughout the abdominal cavity. On histopathology and immunohistochemistry, neoplastic cells were found throughout the abdominal cavity; 60–95% exhibited moderate-to-strong cytoplasmic immunoreactivity for cytokeratin, vimentin, and Wilms tumor 1 protein. The final diagnosis was an epithelioid mesothelioma. Our case illustrates the utility of cytology, immunocytochemistry, and its relation to histology and immunohistochemistry. We also reviewed the reported cases of feline mesothelioma.     

Ovarian and intestinal angiomatosis in a horse

Dozens of red, raised nodules scattered along the serosal surface of the small intestine and the right and left ovaries were observed as incidental findings on gross examination in a 21-year-old Thoroughbred mare euthanatized for severe lameness. Histologically, these nodules were composed of numerous, variably sized, redundant vascular profiles filled with red blood cells and fibrin thrombi. Based on the presence of multiple nodules composed of benign vascular channels scattered within the small intestine and ovary, a diagnosis of angiomatosis is proposed. To the authors' knowledge, this is the first report of small intestinal and ovarian angiomatosis in a horse.     

Equine histoplasmosis presenting as a tumor in the abdominal cavity.

A 3.5-year-old Thoroughbred mare presented at necropsy with a large mass at the root of the mesentery and multiple smaller mesenteric masses. The mucosa of the small intestine contained numerous raised nodules. Histologic examination revealed severe granulomatous mesenteric lymphadenitis and enteritis. Epithelioid macrophages and multinucleated giant cells frequently contained numerous intracytoplasmic yeast organisms, which were strongly positive on immunohistochemical staining when using a polyclonal antibody against Histoplasma spp. A diagnosis of abdominal histoplasmosis was made based on the gross, microscopic, and immunohistochemical findings.     

Mycobacterium infection in a captive-reared capercaillie (Tetrao urogallus)

One captive male capercaillie (Tetrao urogallus) was found dead on December 1993 at the breeding center of capercaillie in Catalonia, Spain. The bird was emaciated and, at necropsy, had numerous nodules of various sizes subcutaneously in the cervical region, pleura, lungs, liver, spleen, and mesentery. Microscopic examination revealed granulomatous lesions with central caseous necrosis, epithelioid cells, giant cells, and few lymphocytes in all affected organs. Numerous acid-fast bacilli were demonstrated in the tubercles with Ziehl-Nielsen stain.     

Round cell variant of myxoid liposarcoma in a Japanese Macaque (Macaca fuscata)

A 5-year-old, female, Japanese Macaque (Macaca fuscata) was diagnosed with round cell variant of myxoid liposarcoma. At necropsy, multifocal to coalescing, reddish tan to white nodules, ranging from 0.5 to 1 cm in diameter, were noted throughout the omentum and retroperitoneum. Similar neoplastic nodules were also present in diaphragm, abdominal wall, and on hepatic capsule. Microscopically, neoplastic masses consisted of round to polyhedral cells, which had round, often eccentric nuclei and abundant eosinophilic granular and microvacuolated cytoplasm; Oil red O staining demonstrated large numbers of lipid droplets in the cytoplasm. Ultrastructurally, the cytoplasm of the tumor cells was packed with occasional lipid vacuoles and numerous enlarged mitochondria. Immunohistochemistry revealed tumor cells were positive for vimentin, while negative to cytokeratin, actin, and Factor VIII-related antigen. To the authors' knowledge, this is the first report of round-cell variant of myxoid liposarcoma in nonhuman primate.     

Colonic ganglioneuromatosis in a horse

Ganglioneuromas are complex tumors that arise in peripheral ganglia and are composed of well-differentiated neurons, nerve processes, Schwann cells, and enteric glial cells. The term ganglioneuromatosis (GN) denotes a regional or segmental proliferation of ganglioneuromatous tissue. This report describes an 8-year-old mixed breed horse with GN in a 25-cm segment of small colon. Grossly, the lesion consisted of numerous sessile to pedunculated nodules extending from the serosal surface. Histologic examination revealed the nodules to consist of fascicles of spindle-shaped cells consistent with Schwann cells, clusters of neurons, supporting enteric glial cells, and thick bands of perineurial collagen. Most of the nodules coincided with the location of the myenteric plexus and extended through the outer layer of the tunica muscularis to the serosal surface. Neuronal processes were demonstrated within the lesion with electron microscopy. With immunohistochemistry neurons were positive for neuron specific enolase (NSE) and S-100 and the Schwann cells and enteric glial cells were positive for S-100 and glial fibrillary acidic protein (GFAP). The pathogenesis of GN is poorly understood. GN, although rare, should be included in the differential diagnosis of gastrointestinal tumors in the horse.     

A case of feline gastrointestinal eosinophilic sclerosing fibroplasia limited to the mesentery

An entire, female, mixed-breed cat of unknown age was presented with a 6-week history of lethargy, anorexia and vomiting. There was an increase in the number of white blood cells in the blood, including neutrophils and eosinophils; moderate anaemia; ascites; and possible mesenteric peritonitis. Exploratory laparotomy revealed firm, multifocal small nodules in the mesentery. As the nodules were surgically unresectable, they were biopsied. Histologically, the nodules were composed of thin trabeculae of dense collagen fibres mixed with plump fibroblasts and numerous eosinophils, consistent with feline gastrointestinal eosinophilic sclerosing fibroplasia. Bacteria were not detected on histological examination of the nodules and cytology of the ascites. Remission of disease occurred following treatment with prednisolone and ciclosporin A for 22 days and antibiotics for 40 days. After remission, ciclosporin A was administered for 236 days and then discontinued. Eosinophilia also resolved after treatment with ciclosporin A. The cat is still alive and in good condition on day 689. This report describes what may be an atypical case of feline gastrointestinal eosinophilic sclerosing fibroplasia, lacking involvement of the gastrointestinal tract, and was apparently cured by treatment that involved ciclosporin A.     

Mesenchymal tumor in a female chamois. A case report

A free-living 15-year old female chamois was shot because of illness and emaciation. The examination of the internal organs revealed numerous firm whitish tumour nodules in liver,spleen, mesenterium and peritoneum. Histologically the nature of tumour cells was identified as a metastasizing malignoma of mesenchymal origin. In addition to the blastoma, the parasite burden of the gastrointestinal tract and lungs did very likely contribute to the bad bodily condition of the chamois.     

Multifocal spinal inflammatory myofibroblastic tumors in a juvenile paraparetic dog

A 1-year-old, female English Bulldog presented with a 10-day history of progressive paraparesis. Neuroanatomical localization was consistent with T3-L3 segment myelopathy. Magnetic resonance imaging (MRI) revealed a severely compressive, mildly contrast enhancing, extradural, dorsal, broad-based mass at the level of L3-4. Similar, non-compressive, smaller nodules were present along the extradural space and dura mater of the caudal lumbar spine. Owners elected euthanasia based on these imaging findings and progressive clinical signs. Necropsy, histopathology and immunohistochemistry revealed a mesenchymal mass and nodules, admixed with numerous inflammatory cells. The diagnosis of an extradural inflammatory myofibroblastic tumor (IMT) with a multifocal presentation was made.     

Characterization of an undifferentiated malignancy as a mast cell tumor using mutation analysis in the proto-oncogene c-KIT.

A 6.5-year-old female Boxer was euthanized and presented for necropsy following rapid clinical decline concomitant with the development of numerous tumor masses. The largest of these masses was in the same location as a mast cell tumor that had been previously removed from this dog. Gross examination revealed the presence of nodules 5-200 mm in diameter throughout the body, including the lymph nodes. Histologic analysis showed an influx of round cells with no granules, leading to the provisional diagnosis of systemic lymphosarcoma. Immunohistochemical staining for B- and T-lymphocyte antigens was negative. Molecular tests were used to identify a tandem duplication in the c-KIT proto-oncogene from both the earlier mast cell tumor and the current nodules, implicating a common origin. Addition of molecular testing to conventional necropsy evaluations allowed a definitive diagnosis of mast cell tumors.     

Cutaneous T-cell-rich B-cell lymphoma in a horse

Cutaneous malignant lymphomas are rare in horses and comprise predominantly T-cell-rich B-cell lymphomas. They are characterized by multiple tumour nodules affecting predominantly female horses with a survival rate of months to years. At the final stage, metastases to regional lymph nodes occur, whereas widespread organ involvement is rarely reported. In this case report, a cutaneous T-cell-rich B-cell lymphoma in a 7-year-old standardbred gelding with metastases is described. Clinically, multiple cutaneous and subcutaneous nodules, enlarged superficial lymph nodes, rapid weight loss, and ventral oedema were observed. In addition to the clinical findings, necropsy revealed tumour infiltration in multiple body lymph nodes, a solitary pleural mass, and few pulmonary and intestinal tumour nodules. Microscopically, all neoplasms were composed of a densely packed cell population consisting of large lymphoblastic cells expressing CD79a, and numerous small, round, CD3-positive T lymphocytes. With respect to these findings the diagnosis of a cutaneous T-cell-rich B-cell lymphoma with metastases was made.     

Clinical and pathological features of Aspergillus fumigatus infections in poultry in southern Nigeria

This study was undertaken to supply information on Aspergillus fumigatus infection of poultry in Nigeria. The disease in broiler chicks was characterized by gasping, droopiness, emaciation and heavy mortality while affected grower chickens showed emaciation, weakness, diarrhoea and 17 per cent mortality. The disease was sporadic in laying flocks. Granulomatous nodules were observed in birds that died in each outbreak. The nodules were numerous and affected mainly the lungs and thoracic air sacs in the broiler chicks while only few large nodules were observed mainly in the abdominal air sacs in the layers.     

Highly metastatic ovarian yolk sac carcinoma in a rat

We investigated a highly metastatic ovarian yolk sac carcinoma in a 52-week-old female Crl:CD(SD) rat. Macroscopically, the present case had severe ascites, bilateral ovarian masses and numerous nodules in the abdominal and thoracic cavities. Histopathologically, these masses and nodules were generally composed of two types of cells mimicking a parietal and visceral yolk sac. The parietal cells were round to polygonal, contained eosinophilic droplets and were arranged in nests and cords in the eosinophilic matrix. Both the intracytoplasmic droplets and the matrix were stained positively with PAS. The visceral cells were cylindriform, and proliferated in papillary and tubular patterns and occasionally formed Shiller-Duval body-like structures. In the dissemination sites, the neoplastic cells proliferated on the surface of the various tissues and often infiltrated into deeper parts of the tissues. Immunohistochemically, both neoplastic cells were positive for α-fetoprotein and keratin, and the eosinophilic matrix was positive for laminin. Ultrastructurally, the parietal cells had dilated rough endoplasmic reticulums, which were filled with electron-lucent laminated structures. The visceral cells had poorly to moderately developed intracytoplasmic organelles and were interconnected with desmosomes. Taken together, the present tumor was diagnosed as yolk sac carcinoma arising from the ovary and was characterized by not only high metastasis but also invasive infiltration with biphasic proliferation of the parietal and visceral cells.