USP7 inactivation suppresses APC-mutant intestinal hyperproliferation and tumor development.

Adenomatous polyposis coli (APC) mutation is the hallmark of colorectal cancer (CRC), resulting in constitutive WNT activation. Despite decades of research, targeting WNT signaling in cancer remains challenging due to its on-target toxicity. We have previously shown that the deubiquitinating enzyme USP7 is a tumor-specific WNT activator in APC-truncated cells by deubiquitinating and stabilizing ß-catenin, but its role in gut tumorigenesis is unknown. Here, we show in vivo that deletion of Usp7 in Apc-truncated mice inhibits crypt hyperproliferation and intestinal tumor development. Loss of Usp7 prolongs the survival of the sporadic intestinal tumor model. Genetic deletion, but not pharmacological inhibition, of Usp7 in Apc+/- intestine induces colitis and enteritis. USP7 inhibitor treatment suppresses growth of patient-derived cancer organoids carrying APC truncations in vitro and in xenografts. Our findings provide direct evidence that USP7 inhibition may offer a safe and efficacious tumor-specific therapy for both sporadic and germline APC-mutated CRC.

Diagnosis and treatment of a caecal mucocoele in a dog.

An 11-year-old male intact Staffordshire Bull terrier was referred for diabetic ketoacidosis. Abdominal ultrasonographic examination revealed a 5 cm × 2 cm intraluminal caecal mass-like structure. Exploratory laparotomy and typhlectomy were subsequently performed. Histopathology of the caecal mass-like structure was consistent with a caecal mucocoele, defined as a cystic dilation of the caecal lumen with stasis of mucus. This lesion has been previously described in humans, where it is termed an appendiceal mucocoele. The patient was euthanased 58 days post-operatively due to unrelated diabetic complications.

Scent (Apocrine) Gland Adenocarcinoma in a Wedge-Capped Capuchin Monkey (Cebus olivaceus): Histological and Immunohistochemical Features.

In humans, apocrine gland tumours encompass a heterogeneous group of uncommon neoplasms with varied and unpredictable biological behaviour. They can be slow-growing lesions, recur after excision, produce lymph node metastasis in up to 50% of cases or lead to tumour-related death. We document a malignant scent adenocarcinoma in a wedge-capped capuchin monkey (Cebus olivaceus). Immunohistochemical labelling revealed complete absence of myoepithelial cells, a finding usually considered a hallmark of malignancy in humans; however, after a 2-year follow-up, the neoplasm had not recurred. This is the first detailed report of the pathology of a spontaneous scent (apocrine) gland adenocarcinoma in a non-human primate.

Aberrant Expression of Cell Cycle Regulator 14-3-3-σ and E-Cadherin in a Metastatic Cholangiocarcinoma in a Vervet Monkey (Chlorocebus pygerythrus).

We present a unique case of metastatic cholangiocarcinoma with concurrent abdominal cestodiasis in an African green monkey (Chlorocebus pygerythrus) that presented with respiratory insufficiency and abdominal discomfort. There were multiple white-grey masses in the liver and colonic serosa alongside intra-abdominal parasitic cysts. Histopathologically, the liver masses were composed of poorly-differentiated epithelial cells that formed densely cellular solid areas and trabeculae. The neoplastic cells were strongly immunopositive for CK7 but negative for Hep-Par1 antigen, which confirmed a diagnosis of cholangiocarcinoma. Interestingly, there was strong and diffuse neoexpression in the tumour of the cell cycle regulator 14-3-3σ, which is not constitutively expressed in normal liver. There was aberrantly strong expression of E-cadherin, a key cell-cell adhesion protein, in neoplastic cells with evidence of cytoplasmic internalization. This is the first immunohistochemical analysis of 14-3-3σ and E-cadherin in a liver neoplasm in an animal species and the use of these markers requires further investigation in animal liver neoplasms.

Primary Verocay Body-rich Epididymal Leiomyosarcoma in a Dog.

Leiomyosarcomas arising from paratesticular structures are rare. We report a case of epididymal sarcoma in an aged male Rottweiler that had histological features suggestive of neural origin but with muscular histogenesis confirmed by immunohistochemistry. Histologically, the lesion comprised a hypercellular neoplasm that had interlacing bundles of spindloid cells, prominent nuclear palisading and many Verocay bodies. Immunohistochemically, the neoplastic cells were strongly positive for smooth muscle markers but negative for neural markers, leading to the diagnosis of leiomyosarcoma. While the presence of nuclear palisading and Verocay bodies has been regarded as strong evidence for the diagnosis of schwannomas, the present report documents the presence of true Verocay bodies in a non-neuronal tumour. It also indicates that immunophenotyping is required for an accurate diagnosis when Verocay bodies are detected in sarcomatous or spindle cell tumours and provides prognostic information on this case. To the best of our knowledge, this is the first report of the presence of true Verocay bodies in a neoplasm other than a nerve sheath tumour in animals.

Avian Papilloma and Squamous Cell Carcinoma: a Histopathological, Immunohistochemical and Virological study.

In this retrospective study, we describe the histopathological findings in seven papillomas and 45 squamous cell carcinomas (SCCs) from psittacine birds, raptors and domestic fowl. The age of affected birds ranged from 3 to 40 years, with median age significantly higher in psittacines (P = 0.014). The majority of tumours were located in the skin (24/52, 46.2%) or uropygial gland (10/52, 19.2%). Thirty of the SCCs (66.7%) were well differentiated and 15 (33.3%) were poorly-differentiated. SCCs exhibited a significantly higher degree of nuclear pleomorphism (P = 0.005) and a greater proportion were ulcerated (P = 0.001) compared with papillomas; however, there was no significant difference in mitotic count (MC) or inflammation score. The expression of cyclo-oxygenase (COX)-2 and E-cadherin was investigated by immunohistochemistry. The COX-2 total score (TS) was significantly higher in SCCs compared with papillomas (P = 0.002), but the difference between COX-2 TS of well- and poorly-differentiated SCCs was not significant. COX-2 labelling was predominantly cytoplasmic, but some tumours had concurrent membranous and/or perinuclear labelling. SCCs with membranous labelling had a significantly higher MC (P = 0.028). A significantly higher proportion of SCCs were negative for E-cadherin compared with papillomas (P = 0.042), but there was no significant difference between well- and poorly-differentiated SCCs. Fourteen papillomas and SCCs from psittacines were also tested by polymerase chain reaction for the presence of Psittacus erithacus papillomavirus 1 and Psittacid herpesvirus 1, but all samples tested negative. We demonstrate for the first time the expression of COX-2 and E-cadherin in avian tissues, and suggest that these markers may be useful in differentiating papillomas from SCCs, particularly when sample size is small.

Pemphigus erythematosus and cutaneous epitheliotropic lymphoma in a Labrador Retriever dog.

BACKGROUND: Paraneoplastic pemphigus is an autoimmune blistering skin disease associated with concurrent neoplasia that is rarely observed in veterinary medicine. CASE DESCRIPTION: This case report presents a ten-year-old female Labrador Retriever dog with generalized seborrhea and alopecic, crusting and ulcerative lesions in the periocular and perioral regions, the lips and the groins. FINDINGS/TREATMENT AND OUTCOME: Hematology analysis showed a marked increase in the number of lymphocytes, while the rest of the values were normal. Skin biopsies were collected and the histological findings were consistent with pemphigus in association with an epitheliotropic lymphoma. Immunohistochemical analysis was performed. There was deposition of immunoglobulin G (IgG) in the basement membrane and in the intercellular space that corresponded with an immunostaining pattern characteristic of pemphigus erythematosus (PE). The lymphoma was positive to CD3 cells and was classified as a T-cell epitheliotropic lymphoma. CONCLUSION: To our knowledge, this is the first case of PE and cutaneous lymphoma coexisting in a dog, expanding the list of associations between immune-mediated diseases and cancer in dogs, and providing support to the eventual connection between autoimmunity and neoplasia in this species.

Malignant Cutaneous Peripheral Nerve Sheath Tumour with Rhabdomyosarcomatous Differentiation (Triton Tumour) in a Domestic Cat.

Divergent differentiation is encountered frequently within human malignant peripheral nerve sheath tumours (MPNSTs). The new component is often a rhabdomyosarcoma, but in animals this specific form of divergent differentiation within MPNSTs has only been reported once (in a dog). Incisional wedge biopsy of a locally extensive, ventral abdominal wall mass, which extended from the dermis to the subcutis, from a 12-year-old female domestic shorthaired cat, was performed. The tissue was examined with routine haematoxylin and eosin staining and immunohistochemical methods. A malignant neoplasm with spindle and polygonal cell components and progression towards a rhabdomyosarcomatous phenotype was observed. Both neoplastic cell populations exhibited strong expression of vimentin and there was multifocal expression of S100 and desmin. There was strong cytoplasmic labelling for α-sarcomeric actin and muscle actin and weak labelling for myoglobin within the cells positive for desmin. There was multifocal positive nuclear labelling for myogenin. Glial fibrillary acidic protein, α-smooth muscle actin, microphthalmia-associated transcription factor and melanoma antigen recognized by T cells were not expressed. Microscopical features, aided by immunohistochemistry, identified a MPNST with progression towards a rhabdomyosarcomatous phenotype, a so-called 'triton tumour'. A Schwann cell component could account for the divergent patterns of growth, given the plasticity of the neural crest. Nerve sheath tumours have been reported in the skin and subcutis of cats and are a differential diagnosis of feline cutaneous spindle cell neoplasms.

Endocardial Peripheral Nerve Sheath Tumour with Features of a Benign Schwannoma in a Donkey.

A peripheral nerve sheath tumour, with features of a benign schwannoma and arising from the endocardium of the right ventricle, was found incidentally during routine post-mortem examination of a 28-year-old gelding donkey. Macroscopically, five round to oval, white to grey and red, firm masses, firmly attached to the endocardium were identified. Microscopically, the endocardium and adjacent subendocardium were infiltrated by a variably demarcated, non-encapsulated mesenchymal neoplasm with features of a benign schwannoma, including concurrent presence of Antoni A and Antoni B areas, nuclear palisading, neoplastic cells with enlarged bizarre nuclei ('ancient change') and the formation of Verocay-like bodies. Immunohistochemically, the tumour cells were variably strongly positive for expression of S100 and glial fibrillary acidic protein. This is the first cardiac tumour reported in a donkey and is macroscopically, histologically and immunohistochemically similar to endocardial schwannoma occurring in Wistar rats.

Benign Bilateral Adenomyoepithelioma of the Mammary Gland in a Ring-tailed Lemur (Lemur catta).

Naturally occurring mammary tumours are uncommon in prosimians. A 20-year-old female ring-tailed lemur (Lemur catta) developed bilateral enlargement of the mammary glands. Surgical removal revealed that both masses were comprised of multiple nodules and cystic areas that entirely replaced the normal glands. Histologically, a benign neoplastic biphasic cellular proliferation, composed of luminal-epithelial and basal-myoepithelial components, was identified. Immunohistochemical analysis for expression of cytokeratin (CK) AE1/AE3, CK7, CK5 + 8, CK14, vimentin, p63 and 14-3-3σ highlighted the biphasic nature of the neoplasm. A low mitotic count, low Ki67 labelling index, expression of oestrogen receptor-α, lack of expression of human epidermal growth factor receptor and a 3-year disease-free period without recurrence supported the benign nature of the tumour. Macroscopically, histologically and immunohistochemically this neoplasm resembled benign adenomyoepithelioma of the breast in women. This is the first complete report of a naturally occurring mammary tumour in a ring-tailed lemur.

Retrospective evaluation of COX-2 expression, histological and clinical factors as prognostic indicators in dogs with renal cell carcinomas undergoing nephrectomy.

Limited veterinary literature is available regarding prognostic markers for canine renal cell carcinoma (CRCC). We retrospectively evaluated COX-2 expression, histological and clinical features associated with prognosis of CRCC. Sixty-four cases post-nephrectomy were included, 54 had histopathological assessment and 30 had COX-2 immunostaining performed. Eight dogs (13%) had metastatic disease at initial diagnosis. Twenty-seven dogs (42%) received adjuvant therapy after nephrectomy. On univariate analysis, COX-2 expression, mitotic index (MI), histologic type, vascular invasion, neoplastic invasiveness and metastasis at diagnosis were significantly associated with overall median survival time (MST). COX-2 score (COX-2 score > 3 MST 420 days versus 1176 days if COX-2 score <3; P = 0.011) and MI (MI > 30 MST 120 days versus 540 days for MI < 30; P = 0.003) were the only variables associated with CRCC outcome on multivariate analysis. The addition of MI and COX-2 immunostaining to standard histopathological evaluation would help predicting outcome in CRCC patients.

Multicentric Benign Epithelial Inclusions in a Free-ranging Risso's Dolphin (Grampus griseus).

This report describes the histological and immunohistochemical features of multicentric, benign, epithelial inclusions (BEIs) in a free-ranging, adult, female Risso's dolphin (Grampus griseus). The differential diagnoses included ectopic hamartomatous epithelial inclusions, non-Müllerian choristoma, Müllerian choristoma and low-grade metastatic carcinoma/mesothelioma. The most likely diagnosis of such BEIs was multicentric, embolic, reactive mesothelium, as suggested by cytomorphological and immunophenotypical features of the BEIs, the occurrence of focal pleural rupture and the immunophenotype of the pleural mesothelium. The former represents a pathological condition not previously reported in a marine mammal species, rarely described in animals, and relatively infrequently recognized in man.

High-grade astrocytoma (Glioblastoma Multiforme) in an Atlantic spotted dolphin (Stenella frontalis).

This report describes the gross, microscopical and immunohistochemical features of a high-grade astrocytoma (glioblastoma multiforme) in an adult male Atlantic spotted dolphin (Stenella frontalis). On necropsy examination, a 5 × 2.5 × 2 cm, poorly demarcated, red, friable and locally expansile mass effaced the thalamus and the left periventricular region and extended to the left lateral ventricle of the brain. Microscopically, the mass consisted of haphazardly arranged bundles and rows of interweaving polygonal to spindle-shaped cells. These often palisaded along serpentine foci of necrosis and were surrounded by prominent vessels. Immunohistochemically, the neoplastic cells expressed glial fibrillary acidic protein, but not vimentin, S100 protein, neuron-specific enolase or neurofilament protein. A diagnosis of high-grade astrocytoma was made and this represents the first description of a glioma in a cetacean species.

Immunohistochemical labelling of cyclooxygenase-2 in lung lesions of calves infected with Mycoplasma bovis.

The pathogenesis and persistence of Mycoplasma bovis (Mb) infection of the respiratory tract is incompletely understood. Cyclooxygenase (COX)-2 is overexpressed during inflammatory responses by different cell types in the lung. This study evaluated COX-2 expression immunohistochemically in the inflammatory lesions of calves with naturally occurring and experimentally induced Mb pneumonia. Experimentally infected lungs showed catarrhal bronchointerstitial pneumonia and varying degrees of peribronchiolar mononuclear cell cuffing. Lesions in calves with spontaneously arising disease included exudative bronchopneumonia and extensive foci of coagulative necrosis surrounded by inflammatory cells. Mb antigen was located in epithelial and inflammatory cells in the airway lumina and surrounding areas of necrosis. COX-2 protein was detected in the lung of all infected calves and was localized to goblet cells, bronchial, bronchiolar and alveolar epithelial cells and macrophages. COX-2 protein was overexpressed during Mb infection and was always associated with areas of pneumonia and with the presence of Mb antigen.

Morphologic and immunohistochemical features of Merkel cells in the dog.

Merkel cells (MCs) are specialized skin receptors characterized by their particular location and close association with nerve terminals. They also are cells with a presumptive neuroendocrine function and are considered as part of the diffuse neuroendocrine system. By using commercially available monoclonal and polyclonal antibodies in samples of dog skin, MCs were properly distinguished from other clear cell types in the epidermis. They expressed cytokeratins 7, 8, 20, EpCAM, NSE, CGA, SYN, S100 protein, and NF, presented diverse cytological features and arrangements depending on the location considered, and showed pronounced heterogeneity with markedly different expression and distribution patterns for antibodies used. Anti-CK20 presented as the most reliable and specific antibody for their identification. The present study increases our knowledge of MCs and establishes a basis for future studies of the role(s) of the MCs in diseased tissues of the dog skin, including the cutaneous neuroendocrine (Merkel cell) tumour.

Cyclooxygenase-2 expression in pigs infected experimentally with Mycoplasma hyopneumoniae.

Porcine enzootic pneumonia, primarily caused by Mycoplasma hyopneumoniae (Mh), is a contagious disease characterized by catarrhal bronchointerstitial pneumonia. Previous studies have evaluated immunohistochemically the distribution of Mh, different cellular populations and cytokines during Mh-induced pneumonia. Cyclooxygenase (COX)-2 is overexpressed during inflammatory responses by different cell types in the lung. The aim of this study was to elucidate the possible role of COX-2 in the pathogenesis of porcine enzootic pneumonia. COX-2 protein was detected by immunohistochemistry in formalin-fixed, paraffin wax-embedded lung tissues from 10 pigs infected experimentally with Mh. Ten pigs were inoculated intranasally with Mh and killed in pairs weekly from 1 to 5 weeks post inoculation. Three Mh-free pigs were taken as controls. Bronchial and bronchiolar epithelial cells, bronchial submucosal glands and a small number of macrophages in the bronchoalveolar exudate expressed COX-2. COX-2 protein was always associated with areas of pneumonia and expression was minimal in lungs from control pigs. These results suggest that COX-2 plays a role in the pathogenesis of Mh-infection.

Primary central nervous system T-cell lymphoma in a common dolphin (Delphinus delphis).

This report describes the pathological findings in an adult female short-beaked common dolphin (Delphinus delphis) stranded alive in the Canary Islands. Necropsy examination revealed the presence of a nodular neoplastic growth in the central nervous system (CNS) at the level of the thalamus. Microscopical examination revealed the mass to be a lymphoma and immunohistochemical labelling demonstrated a T-cell origin. No significant lesions were observed in other organs, including lymphoid organs. This is the first report of a primary T-cell lymphoma in the CNS in cetaceans.

Immunopathological study of parasitic cholangitis in cetaceans.

This paper describes the immunophenotype of cellular inflammatory infiltrates in chronic cholangitis in six common dolphins (Delphinus delphis), four striped dolphins (Stenella coeruleoalba), three Atlantic spotted dolphins (Stenella frontalis) and one pygmy sperm whale (Kogia Breviceps) found stranded along the coasts of the Canary Islands (Spain). A panel of 5 antibodies previously tested in dolphins (anti-CD3, -IgG, -MHC class II, -S100 protein and -lysozyme) were used. The present work also reports cross reactivity with dolphin antigens of two antibodies not used to date in dolphins (anti-mouse iNOS and anti-mouse Foxp3). The most common type of cholangitis found was chronic granulomatous cholangitis, associated with the presence of the parasite Campula spp., or its eggs in bile ducts. The cellular composition of the hepatic inflammatory infiltrate associated to chronic parasitic cholangitis was closely similar to that found in the cortex of control lymph nodes, including the presence of S100(+) and MHC class II(+) dendritic-like cells in lymphoid follicles and interfollicular areas. Only occasional macrophages expressed iNOS, whereas Foxp3(+) lymphocytes were not found in any of the lesions described in the different types of cholangitis.

Adrenohepatic fusion in domestic ferrets (Mustela putorius furo).

We describe two cases of adrenohepatic fusion (AHF) in domestic ferrets (Mustela putorius furo). This condition is defined as the union of hepatic tissue with the adrenal gland with close fusion of the respective parenchymal cells and lack of a fibrous capsule between the two cell populations. AHF is believed to be a congenital anomaly caused by failure of retroperitoneal mesenchyme to stimulate capsule formation, promoting the fusion of the structures. Two male domestic ferrets had a mass adherent to the liver, comprising adrenal gland with areas of fusion between the liver parenchyma and adrenal cortex. There was no evidence of a capsule separating the hepatic and adrenal cell populations. Clinical signs related to either the liver or adrenal gland were not observed, so this was considered to be an incidental finding.

Use of CD10 as a marker of canine mammary myoepithelial cells.

CD10 is an important cell marker in the diagnosis of acute lymphoblastic leukaemia and of breast myoepithelial (ME) cells in humans. The objective of this study was to assess the value of CD10 as a marker of canine ME cells using immunohistochemistry on routinely processed normal, dysplastic and neoplastic mammary tissue. Five different CD10 positive cell types were identified on the basis of cell morphology, pattern of immunoreactivity, and on the co-expression of additional cell lineage-specific markers. Type 1 cells were typical fusiform cells with a ME cell phenotype (calponin- and cytokeratin [CK] 14-positive, CK8/18-negative). Type 2 cells were typical or atypical polyhedral cells with a luminal epithelial (LE) cell phenotype (calponin- and CK14-negative, CK8/18-positive). Type 3 cells had a type 1 phenotype with variable morphology, and type 4 were atypical neoplastic cells with a mixed ME/LE phenotype. Type 5 cells were typical fusiform cells with a stromal phenotype. Type 1 cells were considered normal ME cells and were found in all sample types; type 2 cells were considered normal or neoplastic LE cells and were also found in all sample types; types 3 and 4 cells were restricted to tumour samples and to malignant tumours, respectively, and type 5 cells were found in all sample types, although predominantly in neoplastic tissue. The findings indicate that the CD10 antigen is a sensitive (although not specific) marker of canine ME cells in normal, dysplastic and neoplastic mammary tissue. Differences in the distribution and staining intensity of CD10-positive cells suggest a number of potential roles for this protein in the pathogenesis of canine mammary neoplasia.