L.V. Muscatello

Deletion in the EVC2 Gene Causes Chondrodysplastic Dwarfism in Tyrolean Grey Cattle

During the summer of 2013 seven Italian Tyrolean Grey calves were born with abnormally short limbs. Detailed clinical and pathological examination revealed similarities to chondrodysplastic dwarfism. Pedigree analysis showed a common founder, assuming autosomal monogenic recessive transmission of the defective allele. A positional cloning approach combining genome wide association and homozygosity mapping identified a single 1.6 Mb genomic region on BTA 6 that was associated with the disease. Whole genome re-sequencing of an affected calf revealed a single candidate causal mutation in the Ellis van Creveld syndrome 2 (EVC2) gene. This gene is known to be associated with chondrodysplastic dwarfism in Japanese Brown cattle, and dwarfism, abnormal nails and teeth, and dysostosis in humans with Ellis-van Creveld syndrome. Sanger sequencing confirmed the presence of a 2 bp deletion in exon 19 (c.2993_2994ACdel) that led to a premature stop codon in the coding sequence of bovine EVC2, and was concordant with the recessive pattern of inheritance in affected and carrier animals. This loss of function mutation confirms the important role of EVC2 in bone development. Genetic testing can now be used to eliminate this form of chondrodysplastic dwarfism from Tyrolean Grey cattle.

Molecular Phenotype in Mammary Tumours of Queens: Correlation between Primary Tumour and Lymph Node Metastasis

The molecular characterization of mammary tumours represents a new stage in the development of effective predictive models and targeted therapies. The aim of this study was to evaluate the relationship between the molecular phenotype of a primary feline mammary tumour and that of a related lymph node metastasis. Twenty-one mammary tumour samples and their lymph node metastases were selected and evaluated immunohistochemically for expression of oestrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 (c-erbB-2), cytokeratin 5/6, cytokeratin 14, cytokeratin 19 and protein 63. Mammary tumours were classified into five subtypes: luminal A, luminal B, c-erbB-2 overexpressing, basal-like and normal-like, based on an algorithm applied in both human and veterinary medicine. Concordance between the primary tumour and its lymph node metastasis was detected in 12 of 21 cases (57.1%). In the remaining nine cases (42.9%) there was discordance in the molecular profile at the two sites. Therefore, the tumour molecular profile must be evaluated in both sites in order to obtain definitive identification of the tumour profile (or profiles) and to plan an appropriate therapy.

Molecular portrait-based correlation between primary canine mammary tumor and its lymph node metastasis: possible prognostic-predictive models and/or stronghold for specific treatments?

BackgroundThis study aimed to evaluate the relationship between the molecular phenotype of the primary mammary tumor and its related lymph node metastasis in the dog to develop prognostic-predictive models and targeted therapeutic options.ResultsTwenty mammary tumor samples and their lymph node metastases were selected and stained by immunohistochemistry with anti-estrogen receptor (ER), -progesterone receptor (PR), -human epidermal growth factor receptor 2 (c-erbB-2), -cytokeratin 5/6 (CK 5/6), -cytokeratin 14 (CK14), -cytokeratin 19 (CK 19) and -protein 63 (p63) antibodies. Four phenotypes (luminal A, luminal B, c-erbB2 overexpressing and basal-like) were diagnosed in primary tumors and five (luminal A, luminal B, c-erbB-2 overexpressing, basal-like and normal-like) in the lymph node metastases. Phenotypic concordance was found in 13 of the 20 cases (65%), and seven cases (35%) showed discordance with different lymph node phenotypic profile from the primary tumor.ConclusionsThe phenotype of the primary tumor assumes a predictive-therapeutic role only in concordant cases, meaning that both the primary tumor and its lymph node metastasis should be evaluated at the same time. A treatment plan based only on the primary tumor phenotype could lead to therapeutic failures if the phenotype of the lymph node metastasis differs from that of the primary tumor.

Ellis–van Creveld Syndrome in Grey Alpine Cattle Morphologic, Immunophenotypic, and Molecular Characterization

Ellis–van Creveld (EvC) syndrome is a human autosomal recessive disorder caused by a mutation in either the EVC or EVC2 gene, and presents with short limbs, polydactyly, and ectodermal and heart defects. The aim of this study was to understand the pathologic basis by which deletions in the EVC2 gene lead to chondrodysplastic dwarfism and to describe the morphologic, immunohistochemical, and molecular hallmarks of EvC syndrome in cattle. Five Grey Alpine calves, with a known mutation in the EVC2 gene, were autopsied. Immunohistochemistry was performed on bone using antibodies to collagen II, collagen X, sonic hedgehog, fibroblast growth factor 2, and Ki67. Reverse transcription polymerase chain reaction was performed to analyze EVC1 and EVC2 gene expression. Autopsy revealed long bones that were severely reduced in length, as well as genital and heart defects. Collagen II was detected in control calves in the resting, proliferative, and hypertrophic zones and in the primary and secondary spongiosa, with a loss of labeling in the resting zone of 2 dwarfs. Collagen X was expressed in hypertrophic zone in the controls but was absent in the EvC cases. In affected calves and controls, sonic hedgehog labeled hypertrophic chondrocytes and primary and secondary spongiosa similarly. FGF2 was expressed in chondrocytes of all growth plate zones in the control calves but was lost in most EvC cases. The Ki67 index was lower in cases compared with controls. EVC and EVC2 transcripts were detected. Our data suggest that EvC syndrome of Grey Alpine cattle is a disorder of chondrocyte differentiation, with accelerated differentiation and premature hypertrophy of chondrocytes, and could be a spontaneous model for the equivalent human disease.

Molecular Phenotype of Primary Mammary Tumours and Distant Metastases in Female Dogs and Cats

Distant metastases represent a major step in the progression and fatal outcome of canine and feline mammary carcinomas. Recent studies have characterized the molecular phenotypes of mammary tumours and provided information on molecules that may allow targeted therapy in sites from which the tumours may not readily be surgically resected. Molecular phenotypes were determined immunohistochemically in three feline and two canine cases of mammary neoplasia, each presenting with multiple distant metastases. These tumours and their metastases often overexpressed the c-erbB-2 phenotype. A basal-like phenotype was found in the distant metastases from two cases. These findings suggest that canine and feline mammary tumours with distant metastases may be amenable to novel targeted therapies.

Quantitative immunohistochemical assessment of IgA, IgM, IgG and antigen-specific immunoglobulin secreting plasma cells in pig small intestinal lamina propria.

Abstract Intestinal immune response plays an important defensive role for pathogens, particularly for those transmitted by the oro-faecal route or for foecal shedding modulation. This work examined three parts of intestine from twelve gilts experimentally infected with PCV2-spiked semen, six vaccinated (V group) and six unvaccinated (NV group) against PCV2, 29 and 53 days post infection (DPI). An immunohistochemical investigation for IgA-, IgG- and IgM-antibody bearing plasma cells (PCs) was run on intestinal samples coupled with a sandwich immunohistochemical method to reveal anti-PCV2 antibody-secreting PCs. Plasma cell density was compared in the two groups of animals at 29 and 53 DPI. The IgA, IgG and IgM PC density did not differ between groups but displayed an increase from the upper (villus) to the lower part of the crypts while a decreasing trend in PC density was identified from duodenum to ileum. In the NV group, no increase in anti-PCV2 PC density was demonstrable in the two sampling moment: the amounts of lamina propria PCV2-specific antibody-producing PCs remained constant, 10.55±4.24 and 10.06±5.01 at 29 DPI and 53 DPI, respectively. In the V group a significant increase in PCV2-specific antibody-producing PCs was observed over time. The amounts of PCV2-specific antibody-producing PCs increased from 9.37±13.36 at 29 DPI to 18.76±15.83 at 53 DPI. The data on IgA, IgM and IgG PC counts can be considered reference values in a population of adult pigs. The sandwich method can be proposed as a technique able to identify specific antibody-secreting PCs in formalin-fixed paraffin-embedded tissues. A practical application of the sandwich method is the demonstration of a “booster-like” response of the lamina propria in vaccinated compared to unvaccinated animals. After virus challenge, vaccination induced an increase in the number of PCs containing specific anti-PCV2 antibodies at the level of intestinal mucosa.

Oral Squamomelanocytic Tumour in a Dog: a Unique Biphasic Cancer

In human medicine, squamomelanocytic tumour is a malignant cutaneous neoplasm composed of closely intermingled neoplastic squamous cells and melanocytes. A multinodular gingival tumour in a 16-year-old, mixed breed neutered female dog was examined microscopically. Two populations of neoplastic cells, melanocytic and squamous epithelial cells were intermingled. The melanocytic cells were melan-A positive and cytokeratin AE1-AE3 negative and the squamous component was cytokeratin AE1-AE3 positive and melan-A negative. Bovine papillomavirus was not identified by immunohistochemistry or polymerase chain reaction. A diagnosis of squamomelanocytic tumour was made.

Canine Gastrointestinal Spindle Cell Tumors Efficiently Diagnosed by Tissue Microarray-Based Immunohistochemistry:

Tissue microarray (TMA) is a time- and cost-saving technique allowing the simultaneous immunohistochemical evaluation of multiple tissue samples. The aim of this study was to assess the efficacy of TMA at classifying canine gastrointestinal spindle cell tumors as gastrointestinal stromal tumor (GIST), smooth muscle tumor (SMT), and non-GIST/non-SMT based on the expression of α-smooth muscle actin (α-SMA), desmin, and CD117. Thirty-four cases were investigated on TMAs, sampling 2 cores each. Immunohistochemistry was performed on TMAs and full sections, and the results were compared. Comparing full sections, TMA specificity and sensitivity were 100% and 93.8%, respectively, for α-SMA; 100% and 80.8% for desmin; and 100% and 100% for CD117. TMA allowed the identification of 6 of 6 GISTs, 25 of 26 SMTs, and 2 of 2 non-GIST/non-SMTs. One SMT was misdiagnosed as non-GIST/non-SMT. Based on these results, TMA-based immunohistochemistry is efficient at diagnosing canine gastrointestinal spindle cell tumors and might be applied on large caseloads in a research setting.

Glomeruloid Microvascular Proliferation, Desmoplasia, and High Proliferative Index as Potential Indicators of High Grade Canine Choroid Plexus Tumors:

Choroid plexus tumors (CPT) are intraventricular neoplasms accounting for 10% of all primary central nervous system tumors in dogs. They are frequently classified according to the human WHO classification into choroid plexus papilloma (CPP, grade I), atypical CPP (aCPP, grade II), and choroid plexus carcinoma (CPC, grade III). Histological features observed in canine CPT such as increased vascular density (IVD) and glomeruloid microvascular proliferation (GMVP) are not part of the WHO classification. This multi-centric study aimed to investigate tumor-associated vascular hyperplasia in dogs by determining the prevalence of GMVP and IVD in 52 canine CPT and their association with tumor grade. In addition, the expression of angiogenic factors was assessed by immunohistochemistry in 25 tumors to investigate the pathogenesis of tumor-associated vascular hyperplasia. Based on the classical histological hallmarks, this study of 52 CPT identified 22 (42%) CPP (grade I) and 30 of (58%) CPC (grade III). GMVP was more prevalent in CPC (13/30; 43%) than CPP (1/22; 4%), whereas IVD occurred to a similar extent in CPP and CPC. Desmoplasia was more common in CPC (19/30; 63%) than CPP (2/22; 9%), and similarly, the proliferative index (PI) of neoplastic epithelium was significantly higher in CPC (5.14%) than CPP (0.94%). The majority of CPT expressed platelet-derived growth factor (PDGF), PDGFRα, PDGFRβ, and vascular endothelial growth factor (VEGF) irrespective of tumor grade or tumor-associated vascular hyperplasia. These results suggest that tumor-associated GMVP, desmoplasia, and PI may serve as histological indicators of malignancy in CPT.

Spindle Cell Lipoma in Dogs

Spindle cell lipoma (SCL) is a benign neoplasm of the adipose tissue that may resemble an undifferentiated soft tissue sarcoma (STS). This report describes the histopathological features of 6 SCLs in dogs. All SCLs were located in the subcutis and were composed of bland, occasionally vacuolated spindle cells intermixed with ropey collagen and myxoid matrix. Sudan IV stain performed in 1 case demonstrated the lipid content of vacuoles. Mature adipocytes represented less than 10% of the neoplasm in 3 cases and were absent in the remaining 3. Average mitotic count in 10 high-power fields was 0.17. Neoplastic cells were immunohistochemically positive for vimentin and negative for S100 protein, smooth muscle actin, factor VIII-ra, and MDM2. Awareness of SCL and its specific histopathological features is essential to diagnose this specific tumor. Further studies are needed to document the biological behavior of these tumors in dogs.