Scott Hafner

Spontaneous Equine Pulmonary Granular Cell Tumors: Morphologic, Histochemical, and Immunohistochemical Characterization

Spontaneous equine pulmonary granular cell tumors were diagnosed in six mature horses at slaughter. These tumors were grossly recognized as multiple (5/6) or single (1/6) creamy white, firm nodules. The tumors, located adjacent to bronchi and bronchioles, often invaded airways, resulting in partial to complete occlusion of the lumina. Neoplastic cells were rounded to polyhedral with numerous eosinophilic cytoplasmic granules that reacted uniformly positive with S-100 and neuron-specific enolase antibodies and multifocally with glial fibrillary acidic protein antibodies. These cells were negative for muscle-specific actin, lysozyme, cytokeratin, chromogranin A, and myelin basic protein antigens and did not stain with silver by the Grimelius technique. Uniformly blue-green and scattered pink intracytoplasmic granules were evident with luxol fast blue and periodic acid-Schiff counterstain for myelin and myelin breakdown products. Histochemical and immunohistochemical staining results of these tumors suggest that they are composed primarily of myelinating Schwann cells with lesser numbers of scattered nonmyelinating Schwann cells. The morphologic features of the equine pulmonary granular cell tumors are strikingly similar to those of endobronchial granular cell tumors of human beings.

Viral proventriculitis in chickens

The objectives of the present study were to examine proventriculi of broiler chicks for lesions, and to classify and record the incidence of these lesions. Deep non-purulent necrotizing proventriculitis (accompanied by adenoepithelial hypertrophy and hyperplasia) was the most common (109/220 = 49.5%) light microscopic diagnosis in the proventriculi examined. Degenerating and necrotic alveolar secretory cells had amorphous, granular or vacuolated cytoplasm. Nuclei usually were either pyknotic, karyorrhectic or karyolytic; however, fewer attached or sloughed cells had swollen nuclei with marginated chromatin and clear centres. Basophilic inclusion bodies were never seen. In five cases examined ultrastructurally, hexagonal virus particles were found in intact nuclei (average size = 68.9 nm, n = 89), associated with unbound condensed chromatin, and within vacuolated spaces in the cytoplasm (average size = 62.3 nm, n = 109). DNA in situ hybridization failed to detect adenovirus or polyomavirus nucleic acids. The presence of intralesional virus suggests that a causal relationship might exist between the virus and the proventricular lesions.

An evaluation of methods for the detection of spinal cord in product derived from advanced meat recovery systems.

This study investigated the usefulness of immunohistochemistry, histochemistry, and polarization microscopy in documenting the presence of spinal cord in ground product produced by advanced meat recovery systems (AMRS). A battery of diagnostic stains proved most helpful for definitive documentation of spinal cord in the AMRS product. Antibodies to neurofilament and glial fibrillary acidic proteins were useful for highlighting the presence of neural tissue in comminuted product but when used alone did not definitively differentiate central nervous system tissue from peripheral nerve. Polariscopy, trichrome staining, and immunostaining for synaptophysin were very useful for differentiating spinal cord from peripheral nerve. Spinal cord was found in 2 of 196 AMRS samples when only hematoxylin and eosin staining was used. In a later immunohistochemical subset of the survey study, spinal cord was found in 7 of 17 AMRS samples. More recently, spinal cord tissue has been found in 3 of 26 regulatory samples using hematoxylin and eosin stains combined with immunohistochemical techniques.

Pulmonary Sarcomas in a Young Chicken

Both lungs of a 5-wk-old broiler chicken contained miliary, round, white tumors. Microscopically, these masses were composed of compactly arranged cells with round to oval nuclei and indistinct cytoplasmic borders. Immunohistochemically, tumor cells were positive for vimentin but negative for cytokeratin, S-100 protein, neuron-specific enolase, smooth muscle actin, and muscle-specific actin. Ultrastructurally, tumor cells were separated by collagen bands and some contained collagen fibrils. These results suggest that the primitive mesenchymal cells composing these sarcomas may have originated from precursors of interstitial cells or fibroblasts of the interparabronchial or interatrial septa. DNA was extracted from paraffin-embedded tissues and probed for sequences specific for Mareks disease virus, reticuloendotheliosis viruses, exogenous avian leukosis viruses, and subgroup J avian leukosis viruses. Only sequences specific for subgroup J avian leukosis viruses were identified in the DNA extracted from tumors and surrounding lung.

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 Mareks herpesvirus DNA or leukosis/sarcoma and reticuloendotheliosis proviral DNA.

Neuronal Ceroid-Lipofuscinosis in a Holstein Steer

A young, partially blind Holstein steer was affected by mild cerebral atrophy. Formalin-fixed cerebral gray matter was diffusely yellow brown. Microscopically, there were eosinophilic, autofluorescent granules primarily in the cytoplasm of cerebral neurons. There was also extensive retinal atrophy with complete loss of the rod and cone layers. Ultrastructural examination of affected cerebral neurons revealed a mixture of granular osmiophilic and lamellar patterns in the cytoplasmic storage bodies. This suggests the existence of neuronal ceroid-lipofuscinosis in the Holstein breed.

Splenic Granulomas in Broiler Chickens Produced Experimentally by Inoculation with Eubacterium tortuosum

Eubacterium tortuosum, a gram-positive anaerobic filamentous bacillus, was isolated from splenic and hepatic granulomas of a 56-day-old slaughtered chicken. This isolate was injected intravenously into two groups of 2-week-old broiler chickens, which were necropsied 19 days later. Five of 15 chickens injected with 5 x 10(6) colony-forming units of a 48-hour culture of E. tortuosum developed splenic granulomas typical of those seen in chickens at slaughter. No lesions were observed in chickens given 5 x 10(5) colony-forming units of E. tortuosum or in control chickens receiving phosphate-buffered saline solution. Attempts to reisolate E. tortuosum from experimentally infected chickens were unsuccessful; however, typical filamentous organisms were observed in splenic granulomas of all five affected chickens.

Metastatic Melanomas in Young Broiler Chickens (Gallus gallus domesticus)

Four young broiler chickens affected by multiple melanotic tumors are described. Grossly, there were multiple tumors composed of melanocytes within the skin, skeletal muscle, and multiple visceral organs. Tumors ranged from flattened macules to masses that extensively replaced viscera. Microscopically, melanocytes were often well pigmented, and while there was moderate nuclear anisokaryosis, mitotic rates were low. Immunohistochemical staining of some melanomas with antibodies to S100 proteins, Melan-A, vimentin, or neuron-specific enolase after bleaching of tumor cells with potassium permanganate revealed lack of immunostaining of tumor cells with antibodies to S100, strong positive staining of tumor cells for neuron-specific enolase, moderate staining with antibodies to vimentin, and faint staining for Melan-A. Only neuron-specific enolase staining was evident in unbleached tumor cells. Attempts to identify exogenous avian leukosis viruses in these tumors were unsuccessful.

Cilia-Associated Respiratory Bacillus Infection and Pneumonia in a Pig

Capillaria aerophila, which is found commonly in the respiratory tract of many carnivores,1 has not been reported in raccoons. Capillaria sp. have frequently been described in epithelia of the alimentary tract of raccoons.6,9,10 A recent histopathological survey of Capillaria sp. in alimentary and urinary epithelia of raccoons has revealed a variable prevalence, from a low of 24% in South Carolina to a high of 71% in parts of Pennsylvania.6 The life cycle of Capillaria in raccoons is unknown; therefore, it is difficult to explain this geographic difference. The authors of the survey did not examine the animals’ anal sacs. It appears that capillariasis of raccoons’ anal sacs is common in Oregon, and the sacs get impacted only in isolated cases. This finding may also be true for raccoons in other parts of North America. Further investigations are required to elucidate the extent of infection by Capillaria sp. in the anal sacs of raccoons and to positively identify the species of the nematode. Acknowledgements. I thank Michael Schadt and Sarah Miller for their technical assistance. This project was funded by the Dean’s Office, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon.

Myxosarcomas Associated with Avian Leukosis Virus Subgroup A Infection in Fancy Breed Chickens

Abstract Formalin-fixed suspect tumors were submitted to the Poultry Diagnostic and Research Center at the University of Georgia (Athens, GA) for diagnosis. Samples were from fancy breed chickens with a history of increased tumor prevalence in both hens and roosters. Microscopically, in all the samples, there were neoplastic proliferations of spindle-shaped cells. The matrix surrounding tumor cells stained positively with Alcian blue at pH 2.5, but neoplastic cells did not stain with periodic acid–Schiff. Immunohistochemistry stains were positive for vimentin and neuron-specific enolase and negative for desmin, smooth muscle actin, and S-100 protein. Tumors were determined to be myxosarcomas. All samples were positive for PCR targeting the gp85 avian leukosis virus (ALV) envelope protein. However, analysis of the predicted amino acid sequences in the envelope gene from three separate samples showed high similarity between them and to ALV subgroup A.