Immunohistochemical Distinguishing between Canine Peripheral Nerve Sheath Tumors and Perivascular Wall Tumors

Immunohistochemical Expression of Platelet-Derived Growth Factor Receptor β (PDGFR-β) in Canine Cutaneous Peripheral Nerve Sheath Tumors: A Preliminary Study

Simple Summary

The peripheral nerve sheath tumors are relatively common neoplasms, belong to the soft tissue sarcomas group, and are poorly investigated in veterinary medicine; the diagnosis is complex, and therapeutic options are limited. The platelet-derived growth factor receptors, namely the β subunit, are an important class of tyrosine kinase receptors that can be activated by genetic alterations and contribute to the process of carcinogenesis, so the inhibition of this receptor is an important therapeutic target. Using the immunohistochemical technique, this study aims to evaluate the expression of this receptor in 19 samples, 10 malignant and 9 benign tumors. The results showed that the majority of benign tumors, about 67% of cases, expressed the receptor in less than 25% of neoplastic cells and, in 80% cases of malignant tumors, the receptor was expressed in more than 25% of neoplastic cells. It was also found that, in the larger tumors, the expression of this receptor was significantly higher. With these findings it seems reasonable to speculate that the drugs able to inhibit this receptor, such as toceranib, may be considered in the therapeutic approach of these tumors.

Abstract

As in humans, the prevalence of tumors in companion animals is increasing dramatically and there is a strong need for research on new pharmacological agents particularly for the treatment of those tumors that are resistant to conventional chemotherapy agents such as soft tissue sarcomas (STS). Because malignant (MPNST) and benign peripheral nerve sheath tumors (BPNST) are relatively common STS in dogs, the aim of this retrospective study was to evaluate the immunohistochemical (IHC) expression of PDGFR-β, contributing to its characterization as a potential target for their treatment. A total of 19 samples were included, 9 histologically classified as benign and the other 10 as malignant. The results showed diffuse immunoexpression in the cytoplasm of neoplastic cells. Six (66.7%) BPNST expressed the receptor in less than 25% of neoplastic cells and only three (33.3%) exhibited labelling in more than 25% of neoplastic cells. In contrast, all MPNST expressed PDGFR-β, and in 8 (80%) of these samples, the receptor was expressed in more than 25% of neoplastic cells, and only 2 (20%) cases expressed the receptor in less than 25% of neoplastic cells. PDGFR-β expression was significantly higher in MPNST and larger tumors, suggesting that drugs able to inhibit the activity of this tyrosine kinase receptor, such as toceranib, may be considered in the approach of unresectable tumors and/or in the context of adjuvant or neoadjuvant therapies.

Prevalence and distribution of canine neoplastic and non-neoplastic cutaneous lesions in Serbia: a retrospective study of 2432 Cases (2011 – Mid 2021)

Cutaneous lesions, especially skin tumors in dogs, are among the most common lesions in this animal species. The aim of this study was to identify the most common types of canine cutaneous lesions, to determine the absolute and relative frequency of each type of cutaneous lesion, anatomical locations, mean age, as well as gender and breed distribution. The examination included all samples of cutaneous lesions in dogs obtained by surgical biopsy in veterinary clinics and examined at the Laboratory of the Department of Pathology at the Faculty of Veterinary Medicine, University of Belgrade from the 1st January 2011 to the 1st July 2021. In this period (126 months), a total of 2432 samples of cutaneous lesions were examined, of which 1984 (81.58%) were tumors (1037/1984, 52.27% benign and 947/1984, 47.73% malignant) and 448 (18.42%) non-neoplastic cutaneous lesions. The most commonly found cutaneous tumors were: mast cell tumor (17.34% of all tumors), histiocytoma (9.78%), papilloma (7.91%), lipoma (7.81%), squamous cell carcinoma (7.36%), trichoblastoma (4.44%), hepatoid adenoma (4.39%) and malignant melanoma (4.18%). The most common non-neoplastic cutaneous lesions were: follicular cyst(s) (35.04% of all non-neoplastic lesions), pyogranulomatous chronic dermatitis (23.88%), lymphocytic dermatitis (7.37%), hyperkeratosis (4.24%), and granulomatous dermatitis (3.79%). Our results substantially confirm previously reported data regarding cutaneous neoplastic and nonneoplastic lesions in dogs, and provide updated information on their frequency, animal age, anatomic location and breed distributions.

International Guidelines for Veterinary Tumor Pathology: A Call to Action

Standardization of tumor assessment lays the foundation for validation of grading systems, permits reproducibility of oncologic studies among investigators, and increases confidence in the significance of study results. Currently, there is minimal methodological standardization for assessing tumors in veterinary medicine, with few attempts to validate published protocols and grading schemes. The current article attempts to address these shortcomings by providing standard guidelines for tumor assessment parameters and protocols for evaluating specific tumor types. More detailed information is available in the Supplemental Files, the intention of which is 2-fold: publication as part of this commentary, but more importantly, these will be available as "living documents" on a website (www.vetcancerprotocols.org), which will be updated as new information is presented in the peer-reviewed literature. Our hope is that veterinary pathologists will agree that this initiative is needed, and will contribute to and utilize this information for routine diagnostic work and oncologic studies. Journal editors and reviewers can utilize checklists to ensure publications include sufficient detail and standardized methods of tumor assessment. To maintain the relevance of the guidelines and protocols, it is critical that the information is periodically updated and revised as new studies are published and validated with the intent of providing a repository of this information. Our hope is that this initiative (a continuation of efforts published in this journal in 2011) will facilitate collaboration and reproducibility between pathologists and institutions, increase case numbers, and strengthen clinical research findings, thus ensuring continued progress in veterinary oncologic pathology and improving patient care.