Upregulated MYC expression and p53 mutations may contribute to the oncogenesis of canine Meibomian gland carcinomas.

Sebaceous carcinomas of the human ocular adnexa commonly exhibit pagetoid spread, mutations in tumor-suppressor genes, and protooncogene copy number gain. Sebaceous carcinomas are rarely reported in other species, and while the Meibomian gland (MG) represents the most common ocular adnexal structure of the canine eyelid to develop neoplasia, most are clinically and histologically benign. The objective of this study was to compare molecular features of canine MG carcinomas and adenomas. Two retrospectively identified MG carcinomas were subject to immunohistochemistry and qPCR. When compared with normal glands, MYC was upregulated in benign and malignant MG neoplasms. Aberrant p53 expression was restricted to the nuclei of intraepithelial neoplastic cells in MG carcinomas. Adipophilin expression was diminished in MG neoplasms compared with the normal MG. Our findings, if confirmed in a larger cohort of cases, could suggest that MG oncogenesis in a dog may exhibit similar molecular features as their human counterparts.

Feline Epitheliotropic Mastocytic Conjunctivitis in 15 Cats.

Mast cell infiltration occurs in malignant, inflammatory (eg, allergic, infectious), and idiopathic disease processes in humans and animals. Here, we describe the clinical and histological features of a unique proliferative conjunctivitis occurring in 15 cats. Ocular specimens were examined histologically, and polymerase chain reaction (PCR) for feline herpesvirus 1 (FHV-1) was performed on ocular tissues obtained from 10 cats. Cats had a median age of 8 years (range: 7 months-17.5 years). The known median duration of ocular lesions prior to biopsy was 4 months (range: 1 week-3 years). Ocular disease was unilateral in 12 cats, and 9 cats had coexisting corneal disease. Clinically and histologically, proliferative or nodular conjunctival lesions were noted in 13 cats. The nictitating membrane was affected in 10 cats. Histologically, lesions were characterized by mixed inflammatory infiltrates with an abundance of Giemsa-positive and toluidine blue-positive intraepithelial and subepithelial mast cells, marked edema, and papillary epithelial hyperplasia. Feline herpesvirus 1 was demonstrated by PCR in 1 of 10 cats tested. Follow-up information was available for 14 cats: 8 had no recurrence during a median follow-up period of 17.5 months (range: 4.5-30 months), 2 underwent orbital exenteration, 3 had recurrence that was medically managed, and 1 cat had diffuse conjunctivitis at the time of biopsy and recurrence was deemed irrelevant. Various ocular medications were administered before and after surgical biopsy. This condition was designated as feline epitheliotropic mastocytic conjunctivitis, with intraepithelial mast cells being an essential feature and papillary epithelial proliferation being characteristic but not diagnostic alone. The condition appears to be uncommon and benign. Although the cause is unknown, an allergic component is possible.

Squamous Papillomas of the Conjunctiva in Dogs: A Condition Not Associated With Papillomavirus Infection.

Papillomas of the conjunctival surface in people can be of viral or nonviral origin and are found in high association with human papillomavirus. Canine conjunctival papillomas are seldom described, and published accounts have mostly been associated with canine oral papillomavirus infection. Here, we describe conjunctival squamous papillomas that do not express papillomavirus proteins and compare them with papillomavirus-associated conjunctival papillomas. Conjunctival squamous papillomas presented a distinct histopathologic profile and lacked the cytopathic effects seen in viral papillomas. They appeared as exophytic, papilliferous, pedunculated lesions with delicate fronds and angular terminal margins. Squamous papillomas presented with a delicate fibrovascular core and were associated both clinically and grossly with a feeder vessel. Pigmentation was variable within the epithelium and stroma of these lesions, and inflammatory infiltrates were characteristically minimal. Conjunctival squamous papillomas resembled squamous papillomas of the skin; however, they lacked significant hyperkeratosis. Compared with conjunctival viral papillomas, these masses occurred in older dogs and were smaller and solitary. Furthermore, polymerase chain reaction and immunohistochemistry failed to demonstrate papillomavirus genetic material and antigens in conjunctival squamous papillomas. Both viral and nonviral conjunctival papillomas were considered benign.

Malignant uveal schwannoma with peripheral nerve extension in a 12-week-old color-dilute Labrador Retriever.

The formalin-fixed, amber-colored right globe from a 12-week-old female silver Labrador Retriever dog was submitted to the Comparative Ocular Pathology Laboratory of Wisconsin for light microscopic evaluation. The clinical history described a collapsed anterior chamber and multifocal nodular lesions in the peripheral iris. Histologically, immunohistochemically, and ultrastructurally, the uveal mass was consistent with a malignant schwannoma; there was extension along peripheral nerves within the sclera. The signalment and behavior of the neoplasm distinguish it from the uveal schwannoma of blue-eyed dogs and bear some resemblance to the ocular lesions in human neurofibromatosis. The dilute color mutation may contribute to the cause. Six weeks later, the dog did not develop any additional masses.

Ultrastructural abnormalities of the trabecular meshwork extracellular matrix in Cyp1b1-deficient mice.

Cytochrome P450 1B1 (CYP1B1) is highly expressed in human and murine ocular tissues during development. Mutations in this gene are implicated in the development of primary congenital glaucoma (PCG) in humans. Mice deficient in Cyp1b1 (Cyp1b1(-/-) ) present developmental abnormalities similar to human primary congenital glaucoma. The present work describes the ultrastructural morphology of the iridocorneal angle of 21 eyes from 1-week-old to 8-month-old Cyp1b1(-/-) mice. Morphometric and semiquantitative analysis of the data revealed that 3-week-old Cyp1b1(-/-) mice present a significantly (P < .005) decreased amount of trabecular meshwork (TM) collagen and higher TM endothelial cell and collagen lesion scores (P < .005) than age-matched controls. Collagen loss and lesion scores were progressively increased in older animals, with 8-month-old animals presenting severe atrophy of the TM. Our findings advance the understanding of the effects of CYP1B1 mutations in TM development and primary congenital glaucoma, as well as suggest a link between TM morphologic alterations and increased intraocular pressure.

Clinical, morphologic, and immunohistochemical features of canine orbital hibernomas.

Hibernomas are uncommon benign tumors of brown fat that occur in humans and various animal species. They have not been observed in the orbit of dogs, humans, or other animals. Here we report clinical, light and electron microscopic, and immunohistochemical features of a series of 7 hibernomas arising in the orbital region of dogs. These neoplasms occurred in adult dogs with no breed predilection. The mean age of the affected dogs was 10.4 years (range, 8-13 years). All neoplasms presented as soft lobular masses composed of predominantly round or polygonal neoplastic cells with granular eosinophilic and vacuolated cytoplasm resembling adipocytes. The cytoplasm contained large numbers of pleomorphic mitochondria with dense matrices and indistinct cristae. Immunohistochemical evaluation confirmed positive labeling of neoplastic cells from all cases with uncoupling protein 1 (UCP-1) consistent with brown fat differentiation. Interestingly, rare neoplastic cells also expressed myogenin and myoD, possibly suggesting a common progenitor cell for neoplastic brown adipose and skeletal muscle cells.

Systemic distribution of viral antigen in alpacas persistently infected with bovine pestivirus.

Recently, confirmed occurrences of persistent bovine viral diarrhea virus (BVDV) infection in North American alpacas have raised concerns about the role of persistently infected (PI) alpacas in transmission of virus among herds, yet only limited pathological descriptions of persistent infections in alpacas have been reported. The objective of this study was to characterize BVDV antigen distribution in 10 PI alpacas of varying age and to compare viral antigen distribution and localization in tissues of PI alpacas with 5 PI calves of varying age. Ocular dysplasia was evident in 1 PI alpaca, constituting the first reported congenital ocular lesion in PI alpacas. Viral antigen was widely distributed in alpaca tissues and was prominent in neurons, endothelial cells, and vascular tunica media myocytes but had limited distribution in lymphoid tissues and moderate distribution in epithelium of several organ systems of alpacas. Macrophages in the alpaca gastrointestinal system submucosa and lymph node medullary sinuses often had prominent labeling. In addition, only 1 alpaca had antigen labeling in the bone marrow in contrast to PI cattle. Labeled cells in calf tissues were more widely distributed, occurring prominently in lymphoid and epithelial tissues. Common features of the 2 host species were widespread antigen labeling and absence of lymphoid depletion.

Bilateral buphthalmia in a 4-month-old Texas longhorn steer.

Congenital ocular disease occurs uncommonly in cattle, with multiple abnormalities reported only sporadically in the literature. This report describes a case of anterior segment dysgenesis resulting in glaucoma in a 4-month-old Texas Longhorn steer. On clinical exam, bilateral buphthalmia was present and intraocular pressures exceeded 47 mm Hg in both eyes. On histopathologic examination, the iridocorneal angle and filtration apparatus were distorted due to collapse of the ciliary cleft and anterior displacement of the anterior portion of the ciliary body. No evidence of inflammation or other causes of glaucoma were recognized.

Investigation of prognostic indicators for human uveal melanoma as biomarkers of canine uveal melanoma metastasis.

OBJECTIVE: To evaluate if 14 genes that discriminate metastasising and non-metastasising human uveal melanomas can differentiate metastasising and non-metastasising uveal melanomas in dogs. METHODS: Nineteen archival biopsies of eyes with a histopathological classification of primary benign (n = 9) and malignant (n = 10) uveal melanoma were selected. Thoracic and/or abdominal metastases confirmed metastatic spread of the primary tumour in seven dogs during the follow-up period. Gene expression was assayed by Reverse Transcription-quantitative Polymerase Chain Reaction. Genes displaying statistically significant differences in expression between the metastasising and non-metastasising tumours were identified. RESULTS: Four genes (HTR2B, FXR1, LTA4H and CDH1) demonstrated increased expression in the metastasising uveal melanomas. CLINICAL SIGNIFICANCE: This preliminary study illustrates the potential utility of gene expression markers for predicting canine uveal melanoma metastasis. The genes displaying elevated expression in the metastasising tumours are part of a 12-discriminating gene set used in a routine assay, performed on fine needle aspirate biopsies collected without enucleation, for predicting human uveal melanoma metastasis. Further work is required to validate the results.

Osteosarcoma of the maxilla with concurrent osteoma in a southern sea otter (Enhydra lutris nereis).

Southern sea otters (Enhydra lutris nereis) are threatened marine mammals that belong to the family Mustelidae and are native to the coast of Central California. Neoplasia is reported infrequently in sea otters. An adult female free-ranging southern sea otter was found alive at Pebble Beach, Monterey County, California, on January 1st, 1994 and died soon after capture. The carcass was submitted to the US Geological Survey - National Wildlife Health Center for necropsy examination. Grossly, a mass with rubbery texture was firmly attached to the left maxillary region of the skull and the nasopharynx was occluded by soft neoplastic tissue. Post-mortem skull radiographs showed an oval, smoothly marginated mineralized opaque mass centered on the left maxilla, extending from the canine tooth to caudal to the molar and replacing portions of the zygomatic arch and palatine and temporal bones. The majority of the mass protruded laterally from the maxilla and was characterized by central homogeneous mineral opacity. Microscopically, the mass was characterized by fully differentiated lamellar non-osteonal bone that expanded beyond the margins of the adjacent normal osteonal bone. Sections of the nasopharyngeal mass were comprised of moderately pleomorphic cells with bony stroma. Gross, microscopical and radiological findings were compatible with maxillary osteosarcoma with concurrent osteoma.

Angiofibroma of the nasal cavity in 13 dogs.

This case series describes a rare entity, nasal angiofibroma, in 13 dogs that were presented to the University of Wisconsin, School of Veterinary Medicine from 1988 to 2000. All dogs in this case series presented with clinical signs and radiographic changes that were strongly suggestive of a locally invasive neoplasm. However, histopathology completed on transnostral core biopsy samples revealed benign appearing vascular proliferation with secondary lymphosuppurative inflammation was established despite cytologic criteria of malignancy present in five dogs. On the basis of the outcomes in this case series, nasal angiofibroma should be considered a differential for dogs presenting with clinical signs consistent with a malignant nasal tumour.

Diagnostic features of feline restrictive orbital myofibroblastic sarcoma.

A progressive debilitating disease of the orbit and adjacent connective tissues of cats has historically been called feline orbital pseudotumor. The authors reviewed clinical, histopathologic, and diagnostic imaging features of this disease in 12 cases from the Comparative Ocular Pathology Laboratory of Wisconsin. The cats' ages ranged from 7 to 16 years (mean, 10.8 years). All cats had a history of severely restricted mobility of the globe and eyelids with secondary corneal disease. Eleven cats (92%) had concurrent involvement of the contralateral eye and/or the oral cavity. Diffuse scleral or episcleral thickening was seen with computed tomography in all clinically affected eyes. Histologically, an insidious infiltration of neoplastic spindle cells in the orbit, eyelids, and periorbital skin and soft tissues, with collagen deposition and a few perivascular lymphocytes, led to entrapment and restricted mobility of the eyelids and orbital tissues. The tumor failed to form a discrete mass, and it spread along fascial planes to the contralateral orbit and eyelids and/or the lips and oral cavity. In all tested cases (n = 10), neoplastic cells were immunohistochemically positive for vimentin, S100 protein, and smooth muscle actin. The authors adopted the term feline restrictive orbital myofibroblastic sarcoma to reflect the restricted mobility of the eyelids and globe and the imaging and histologic features of an invasive yet low-grade myofibroblastic sarcoma.

Canine duplication of Descemet's membrane.

The morphology of a duplication phenomenon of the canine Descemet's membrane (DM) is described in relation to signalment, history, and ocular disease status. Sixty-six canine eyes from the Comparative Ocular Pathology Laboratory of Wisconsin archives between 2000 and 2007 were examined. All cases were stained with hematoxylin and eosin and Alcian blue periodic acid-Schiff (PAS), while 14 cases were additionally stained with Masson's trichrome, picrosirius red, cytokeratin AE1/AE3 (CK), vimentin, and alpha-smooth muscle actin (SMA). Transmission electron microscopy (TEM) examination was performed in 3 corneas and in 1 normal control eye. Alcian blue PAS staining and TEM confirmed the basement membrane nature of the abnormal secondary DM. The thickness of the first DM, referred to as the corneal layer (CL) and the second or anterior chamber layer (ACL), were nearly the same, with no significant difference seen (P = .93). In 39% (26/66) of the eyes, a fibrous, collagenous matrix component was present between the CL and ACL, which contains vimentin-positive and alpha-SMA-negative spindle cells (14/14).The corneal endothelial cells in 7/14 eyes stained weakly with CK and strongly in 2 additional eyes. The most frequent histopathologically confirmed, clinical ocular histories were chronic glaucoma in 76% (50/66) of eyes, previous intraocular surgery in 36% (24/66), lens luxation in 21% (4/66), and blunt trauma in 15% (10/66) of the cases. We speculate that activation and migration of endothelial cells, in association with trauma or lens contact, play a role in the pathogenesis of this phenomenon.

Corneal squamous cell carcinoma in a Border Collie.

A 6-year-old, female, spayed Border Collie was presented to the Unit of Comparative Ophthalmology at the Animal Health Trust with a 6-month history of a progressive nonpainful opacity of the left cornea. A keratectomy was performed and the tissue submitted for histopathology. The diagnosis was squamous cell carcinoma. There has been no recurrence of the neoplasm to date (5 months). Canine corneal squamous cell carcinoma (SCC) has not been reported previously in the UK.

Histopathological features of ocular leishmaniosis in the dog.

Canine leishmaniosis (CL) can present with multiple clinical signs and ocular disease is reported to occur in almost 25% of affected dogs. The purpose of the present study was to characterize the nature of inflammation within the eyes of dogs with leishmaniosis and to determine whether parasites were present in these lesions. Eyes from 60 dogs with confirmed leishmaniosis that died or were humanely destroyed over a 4 year period were included in the study. Sections of formalin-fixed globes were stained with haematoxylin and eosin (HE) and subjected to immunohistochemistry using a Leishmania-specific antibody. Clinically evident ocular signs were present in 15 of 60 dogs (13 bilaterally and 2 unilaterally). Thirty-five of 60 dogs received some form of anti-protozoal treatment. In 36 of 120 eyes (30%) a granulomatous inflammatory infiltrate was found and in 32 of 120 eyes (26.6%) the parasite was identified immunohistochemically within the globe. Ocular tissues affected, in order of frequency, were conjunctiva and limbus, ciliary body, iris, cornea, sclera and iridocorneal angle, choroid and the optic nerve sheath. Different microscopical patterns were defined in each of these structures. Leishmania organisms and associated inflammation can be found in different ocular tissues, accounting for some of the ocular clinical signs described for this disease.

Metastatic iridociliary adenocarcinoma in a labrador retriever.

An enucleated left eye from a 15-year-old female spayed Labrador Retriever was received by the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) for histopathologic evaluation. Routine histologic preparation included staining with hematoxylin and eosin, and with alcian blue periodic acid-Schiff (PAS). At necropsy 9 months later, all grossly abnormal tissues (ipsilateral orbit and lung) were submitted to the COPLOW for histopathologic evaluation. Histopathologic evaluation of the globe revealed extensive invasion of the uvea and sclera by a pleomorphic cell population that formed disorganized cords and exhibited PAS-positive basement membrane material. Necropsy revealed a morphologically similar tumor in the ipsilateral orbit and lung. On immunohistochemical examination, the intraocular tumor stained diffusely immunopositive for vimentin, S-100, and neuron-specific enolase and multifocally, sparsely immunopositive for cytokeratin AE1/AE3. The orbital and thoracic tumors stained positively for vimentin but negatively for cytokeratin AE1/AE3. There are few reports of canine metastatic iridociliary adenocarcinoma in the literature; this is the first with immunohistochemical analysis.

Uveal spindle cell tumor of blue-eyed dogs: an immunohistochemical study.

Immunohistochemical techniques were used to investigate the origin of a spindle cell tumor in the anterior uveal tract of dogs and the influence of ultraviolet radiation on the development of this tumor. Thirteen tumors were identified from the 4,007 canine ocular samples examined at the Comparative Ocular Pathology Laboratory of Wisconsin between 1978 and 2005. Siberian Husky and Siberian Husky mix dogs were overrepresented (10/13 dogs, overall median age 10 years). Light microscopic evaluation (all dogs) and electron microscopy (2 dogs) were performed. Immunohistochemical staining included alpha-smooth muscle actin (SMA), vimentin, S-100, desmin, glial fibrillary acidic protein (GFAP), Melan A, microphthalmic transcription factor (MITF-1), protein gene product 9.5 (PGP 9.5), laminin, gadd45, p53, proliferating cell nuclear antigen (PCNA), anti-UVssDNA (antibody for detection of (6-4)-dipyrimidine photoproducts), and telomerase reverse transcriptase (TERT). All tumors occurred in the iris with or without ciliary body involvement and were composed of spindle cells arranged in fascicles and whorls (variable Antoni A and B behavior). All tumors were positive when immunostained for vimentin and S-100. Nine of 13 tumors exhibited GFAP immunopositivity. All tumors were negative for SMA, desmin, Melan A, and MITF-1. Tumors were variably positive for PGP 9.5, laminin, gadd45, p53, PCNA, anti-UVssDNA, and TERT. Electron microscopy revealed intermittent basal laminae between cells. These tumors are morphologically and immunohistochemically most consistent with schwannoma. The relationship between spindle cell tumors of the anterior uvea of dogs, altered neural crest, blue iris color, and ultraviolet radiation has not yet been fully elucidated.

Characterizing a rat Brca2 knockout model.

Evidence exists that BRCA2 carriers may have an elevated risk of breast, ovarian, colon, prostate, and pancreatic cancer. In general, carriers are defined as individuals with protein truncating mutations within the BRCA2 gene. Many Brca2 knockout lines have been produced and characterized in the mouse. We previously produced a rat Brca2 knockout strain in which there is a nonsense mutation in exon 11 between BRC repeats 2 and 3, and a truncated protein is produced. Interestingly, while such a mutation in homozygous mice would lead to limited survival of approximately 3 months, the Brca2-/- rats are 100% viable and the vast majority live to over 1 year of age. Brca2-/- rats show a phenotype of growth inhibition and sterility in both sexes. Aspermatogenesis in the Brca2-/- rats is due to a failure of homologous chromosome synapsis. Long-term phenotypes include underdeveloped mammary glands, cataract formation and lifespan shortening due to the development of tumors and cancers in multiple organs. The establishment of the rat Brca2 knockout model provides a means to study the role of Brca2 in increasing cancer susceptibility and inducing a novel ocular phenotype not previously associated with this gene.

Human granulocyte-macrophage colony-stimulating factor DNA cationic-lipid complexed autologous tumour cell vaccination in the treatment of canine B-cell multicentric lymphoma.

This study describes the development of an human granulocyte-macrophage colony-stimulating factor DNA cationic-lipid complexed autologous tumour cell vaccine (hGM-CSF CLDC ATCV) and its implementation, following a chemotherapy treatment protocol, in a randomized, placebo-controlled, double-blinded clinical trial in pet dogs with naturally occurring lymphoma. We hypothesized that the use of this vaccine would result in an antitumour immune response leading to improved first remission duration and overall survival in dogs with B-cell lymphoma when compared with chemotherapy alone. Immune stimulation generated by hGM-CSF CLDC ATCV was assessed by means of surrogate in vivo analysis (delayed-type hypersensitivity [DTH]) as well as an ex vivo cellular assay (lymphocyte proliferation assay). The vaccine approach considered in the current report did not result in clinically improved outcomes. A small measure of immunomodulation was documented by DTH and several modifications to the approach are suggested. This report illustrates the feasibility of clinical trials with vaccine strategies using companion animals with non-Hodgkin's lymphoma.

Immunohistochemical properties of ocular adenomas, adenocarcinomas and medulloepitheliomas.

Ocular medulloepitheliomas, adenomas and adenocarcinomas share a common phenotype and originate from the optic cup neuroectoderm. This can make it very difficult to differentiate between these tumors histopathologically. Therefore, this study focused on identifying a combination of immunologic markers that might be used in the diagnosis of these tumors. These markers included AE1/AE3, CK7, CK20, and telomerase reverse transcriptase (TERT). Routine immunohistochemical staining was performed on 27 whole globes diagnosed with one of these tumors. The tumors that immunostained for TERT showed increasing immunoreactivity as the tumor types increased in aggressiveness. None of the tumor types were immunopositive for CK7. CK20 immunostaining was found in the adenomas but not in the adenocarcinomas or medulloepitheliomas. AE1/AE3 expression was present more consistently in the adenocarcinomas and less frequently in the adenomas. AE1/AE3 expression was present in only one of six medulloepitheliomas. Furthermore, CK20 and TERT showed inverse expression patterns, i.e. TERT increased in expression and CK20 decreased in expression with increasing aggressiveness. These results may be important diagnostic and prognostic indicators for these tumors.