Fibroblast-associated protein-α expression and BPV nucleic acid distribution in equine sarcoids.

Sarcoids are the most common cutaneous tumor of equids and are caused by bovine papillomavirus (BPV). Different clinical subtypes of sarcoids are well characterized clinically but not histologically, and it is not known whether viral activity influences the clinical or histological appearance of the tumors. The aim of this study was to verify whether the development of different clinical types of sarcoids or the presence of certain histological features were associated with BPV distribution within the tumor. The presence of BPV was assessed by polymerase chain reaction (PCR) and visualized in histological sections by chromogenic in situ hybridization (CISH) in 74 equine sarcoids. Furthermore, to better characterize the molecular features of neoplastic cells, immunohistochemistry for S100, smooth muscle actin-α (αSMA), and fibroblast-associated protein-α (FAPα) was performed. The presence of BPV was confirmed in all tissues examined by either or both PCR and CISH (72/74, 97% each). Of 70/74 CISH-positive cases, signal distribution appeared as either diffuse (61/70, 87%) or subepithelial (9/70, 13%); the latter was more frequently observed in the verrucous subtype. However, no statistically significant association was found between clinical subtypes and specific histological features or hybridization pattern. Moreover, CISH signal for BPV was not detected in the epidermis overlying sarcoids nor in the tissue surrounding the neoplasms. By immunohistochemistry, αSMA confirmed the myofibroblastic differentiation of neoplastic cells in 28/74 (38%) sarcoids. Using tissue microarrays, FAPα labelling was observed in neoplastic fibroblasts of all sarcoids, suggesting this marker as a potential candidate for the immunohistochemical diagnosis of sarcoids.

Congenital Tumours and Tumour-Like Lesions in Calves: a Review.

Congenital tumours and tumour-like lesions represent a group of rare disorders in both veterinary and human medicine that arise from tissue remnants and are detected during pregnancy or within the first 2-3 months of life. Different forms of congenital tumours and congenital tumour-like lesions have been reported in calves and their development is poorly understood. They often pose a diagnostic challenge and the referring nomenclature occasionally may be equivocal. Previous reports regarding tumour-like lesions, soft tissue tumours, vascular tumours, round cell tumours and neoplasms of the nervous, peritoneum and urogenital systems are summarized in this review, and the role of genetic factors in the development of these conditions is discussed.

p53 Expression in Canine Liposarcoma Correlates With Myxoid Variant and Higher Proliferative Activity.

Canine liposarcoma is classified as well differentiated (WDL), dedifferentiated (DDL), myxoid (ML), and pleomorphic (PL). Overexpression of the protooncogene MDM2 has been reported in WDL and DDL, but little is known regarding the role of p53 in their tumorigenesis. The aim of this study was to assess p53 expression in canine liposarcoma and compare it with subtype, grade, mitotic count (MC), Ki67 labeling index (LI), and MDM2 expression. Forty-seven cases were included (13 WDL, 3 DDL, 7 ML, and 24 PL); 17 were MDM2-positive (13 WDL, 3DDL, and 1ML). Five were p53-positive (4 ML and 1 WDL) but DDL and PL were consistently negative. p53 expression correlated with higher Ki67-LI, higher MC, and myxoid histotype. No correlation was found with grade and MDM2 expression. Based on these results canine liposarcoma seems to embody a group of neoplasms whose subtypes, especially ML, may represent distinct diseases rather than morphological variants of the same entity.

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.

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.