Microsporidiosis in a young ostrich (Struthio camelus).

Microsporidia are obligate, intracellular, protozoan parasites of a wide variety of vertebrates and invertebrates. Confirmed reports of microsporidial infection of avian species are few (lovebirds, a parrot, and a group of budgerigar chicks). At slaughter, a 14-mo-old ostrich was found to have small intestinal serosal hemorrhages during postmortem inspection. Histologic examination of the small intestine revealed a chronic lymphoplasmacytic to purulent enteritis with mucosal hyperplasia, muscular hypertrophy, and numerous microsporidia that were located within the superficial enterocytes and the lamina propria. Microsporidia have a ubiquitous distribution in nature and are suspected as possible zoonotic agents.

A retrospective study of multicentric bovine renal cell tumors.

Tissues from twenty mature cows with primary renal cell tumors were submitted over an 11-year period because of gross lesions detected during routine slaughter and inspection. Tumors visualized grossly were multiple and bilateral in seven cattle, multiple within one kidney in four cattle, and solitary in nine cattle. The tumors were primarily cortical, yellow-orange to tan, proliferative, well circumscribed, and extended above the capsular surface of the kidney. Tumors were microscopically multiple even when grossly described as solitary lesions, except in one cow. Twelve tumors (60%) were microscopically multiple in one kidney, seven tumors (35%) were multiple and bilateral, and only one cow (5%) exhibited extrarenal metastasis. Tumors from nineteen cows were composed of eosinophilic granular epithelial cells; tumors from one cow were clear cell type. Each tumor contained several histologic patterns. Corpora amylacea, proteinaceous secretions, and hemosiderin were characteristic findings in bovine renal cell carcinoma. All 20 cows with renal cell tumors exhibited positive immunoreactivity to uromodulin (Tamm-Horsfall protein).

Multicentric histiocytosis in young chickens. Gross and light microscopic pathology.

During 1991-94, tissue specimens from 262 young chicken carcasses condemned at slaughter contained novel multicentric proliferations of histiocytelike cells. These tissues had been submitted to the USDA FSIS Eastern Laboratory because of grossly enlarged spleens, livers, or kidneys. The spleens were two to three times normal diameter and contained miliary white or yellow 1-3-mm foci. Similar miliary foci were present throughout the enlarged livers and kidneys. Microscopic examination of these tissues revealed discrete circular nodules expanding splenic periarteriolar lymphoid sheaths, hepatic periportal nodules, and discrete perivascular and more diffuse interstitial nodules replacing renal tubules. Nodules also were present in the pancreas, bone marrow, proventriculus, and lung, with more diffuse infiltrates in intestinal lamina propria. The cells composing these nodules contained irregularly oval, folded, or pleomorphic nuclei and relatively abundant eosinophilic cytoplasm. Mitotic figures and pyknotic nuclei were common. These cells were interpreted to be histiocytes (tissue macrophages or dendritic cells) and did not resemble lymphocytes. These proliferating cells also did not resemble the cell population of commonly diagnosed lymphoid neoplasms of young chickens. No intralesional organisms were detected and polymerase chain reaction analysis failed to detect Marek's herpesvirus DNA or leukosis/sarcoma and reticuloendotheliosis proviral DNA.

Malignant melanocytic neural crest tumor in a young chicken (Gallus domesticus).

A malignant melanocytic tumor was found in an 8-week-old chicken. The tumor, which was composed of melanocytes, ganglion cells, nerves, and primitive pressure receptors, was examined by light microscopy, transmission electron microscopy, and immunohistochemistry. Antibodies to neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), and S-100 protein variably stained nerves, but melanocytes were only rarely immunolabelled by NSE antibodies and there was no specific staining of these cells for S-100 or GFAP. Ultrastructurally, neoplastic melanocytes contained melanin within melanosomes and premelanosomes and did not resemble Schwann cells.

Epicardial keratinaceous cyst in a tawny frogmouth (Podargus strigoides plumiferus).

Tissues from a tawny frogmouth that died acutely in a zoo collection were submitted for histopathologic examination. A small yellow nodule was observed grossly on the ventricular wall by the zoo veterinarian during collection of tissues. Histologically, the epicardial nodule consisted of a well-circumscribed, thinly encapsulated cyst, 4 mm in diameter. The cyst was composed of gradually keratinizing, attenuated, stratified squamous epithelium, one to three cell layers in thickness. The cyst was filled with laminated keratin and a few keratinized epithelial cells. The cyst was separated from the myocardium by a thin layer of adipose tissue. Based on these observations, the structure was diagnosed as an epicardial keratinaceous cyst.

Bovine pulmonary blastomas: histomorphologic description and immunohistochemistry.

Three adult female dairy cattle with pulmonary blastomas were evaluated. The gross lesions at postmortem were described as multiple white circumscribed masses throughout the lungs, with pleural involvement in one cow and lymph node metastasis in the other two cows. Histologically, the tumors contained a dual population of mesenchymal and epithelial neoplastic cells. Epithelial cells formed nests, tubules, and formations resembling bronchioles of normal lung. Mesenchymal cells were spindle shaped with oval nuclei and fibrillar eosinophilic cytoplasm, were large rounded cells with multiple round nuclei and granular eosinophilic cytoplasm, or appeared blast-like, with large hyperchromatic nuclei and amphophilic cytoplasm. The tumors varied greatly in appearance from one field to another within the same tumor. Epithelial cells stained positively with anticytokeratin antibodies. Some spindle-shaped mesenchymal cells exhibited smooth muscle cell differentiation with positive staining with anti-vimentin, anti-muscle-specific actin, and anti-smooth muscle actin antibodies, whereas other rounded mesenchymal cells expressed striated muscle cell differentiation with multiple nuclei and positivity to anti-neuron-specific enolase and anti-muscle-specific actin antibodies. The variable expression of the intermediate filaments and cytoplasmic enzymes indicates multiple pathways of differentiation in the pulmonary blastomas.

Ultrastructural examination and cell count determinations of avian glomeruli from grossly normal and grossly swollen kidneys of broilers at slaughter.

Kidneys from broiler chickens at slaughter (6 to 7 weeks of age and mixed sex) were collected by U.S. Department of Agriculture personnel. Forty kidneys were collected from grossly normal birds with grossly normal kidneys (Group D). Grossly swollen kidneys were collected from birds that were otherwise grossly normal (Group A), that had gross lesions of Marek's disease (Group B), or that had gross lesions of squamous cell carcinoma (Group C). These kidneys were fixed in Carson's 10% buffered formalin, embedded in plastic, sectioned at 2 microns, and then stained with periodic acid-Schiff-hematoxylin for glomerular cell counting. Tissue was also processed for electron microscopy from six Group D birds and from six birds total from Groups A, B, and C that had the most severe histologic glomerular lesions. Glomerular tuft cell counts and visceral epithelial cell counts were performed by light microscopy at a magnification of 100x (oil immersion). Total tuft cell counts of all abnormal groups (A, B, and C) were significantly higher (P < 0.05) than those of Group D. Reptilian glomerular tuft cell counts for all abnormal groups were significantly higher (P < 0.05) than the reptilian glomerular tuft counts for Group D. Mammalian glomerular tuft cell counts for Groups A and B were significantly higher than those of the control group (Group D). Electron microscopic examination of the glomeruli from selected birds revealed no dense deposits in the basement membrane and no effacement of epithelial podocyte foot processes. No essential ultrastructural differences were noted between the control group and the abnormal groups.

Histologic and morphometric examination of avian glomeruli from normal and swollen kidneys of broilers at slaughter.

Normal and abnormal kidneys collected from broiler chickens at slaughter (6 to 7 weeks of age and of mixed sex) were evaluated to establish histopathologic and morphometric parameters for broilers. Normal kidneys (group D) had an overall mean glomerular diameter of 67.4 +/- 27.8 microns. Abnormal groups (Groups A, B, and C) had an average glomerular diameter of 75.2 +/- 32.1 microns, which was significantly different (P < 0.01) from that of Group D. All glomerular diameters in Group A (otherwise normal birds with swollen kidneys) were significantly different (P < 0.01) from corresponding diameters in Group D. In Group B (birds condemned for Marek's disease virus), only the mammalian glomeruli were significantly different from Group D mammalian glomeruli (P < 0.01). A significant increase in glomerular density was observed for all abnormal groups and glomerular types. The data indicate that glomerular diameter and cellularity might be practical and sensitive indicators of early glomerular changes that can occur in grossly swollen kidneys. Increased glomerular density indicates tubular loss or increase in glomerular numbers.