Sumeyye TOYGA(1), M. Caglar KONDU(2), Ender ER(3), Evrim EGEDEN(4), Hazal OZTURK GURGEN(5), Burcu DURSUN(6), S. Seckin ARUN(6), Zuleyha AKGUN(7)
(1)Istanbul University-Cerrahpasa, Faculty of Veterinary Medicine, Graduate School of Education, Department of Pathology, Buyukcekmece, 34500, Istanbul, Turkey (2)Vetelite Veterinary Clinic Kadikoy, 34710, Istanbul, Turkey
(3)GencVet Serdivan Veterinary Clinic, 54050, Sakarya, Turkey
(4)Ada Veterinary Clinic, Besiktas, 34330, Istanbul, Turkey
(5)Istanbul University-Cerrahpasa, Faculty of Veterinary Medicine, Department of Pathology, Buyukcekmece, 34500, Istanbul, Turkey
(6)Vetlab Veterinary Analysis Laboratory, Kadikoy, 34710, Istanbul, Turkey
(7)Istanbul Bilgi University, Department of Radiation Oncology, Sisli, 34060, Istanbul, Turkey
E-Mail: toygasumeyye@gmail.com
INTRODUCTION
Nasal squamous cell carcinoma (SCC) is a malignant neoplasm of epidermal cells in which cells differentiate into keratinocytes. There are opinions that the sensitivity of the nasal planum to ultraviolet rays triggers the development of SCC in the region. In all species, SCC can occur in young animals, but the incidence increases with age. The highest incidence of SCC is in cats 9 to 14 years of age[1]. Although surgical complete excision is considered as the first choice for cutaneous SCC, a good result may not be obtained in lesions in the nasal region, besides, chemotherapy alone has minimal efficacy, and radiotherapy is preferred as a more successful method. Cryosurgery, intralesional therapy, and electrochemotherapy are other treatment modalities. Stereotactic body radiation therapy, on the other hand, involves the delivery of high-dose radiation fractions (20 to 30 Gy) to the target area using an external radiation beam, special positioning equipment, and image- guided therapy application while limiting radiation exposure to organs at risk as a result of rapid dose reduction gradients and reverse planning. It is used to ensure that the radiation is delivered accurately to the target volume[2]. In this study, we aimed to present the clinical oncological approach of a cat diagnosed with SCC in the nasal region, who achieved complete remission with stereotactic body radiation therapy after surgical excision.
MATERIAL-METHOD
The case consists of a 4-year-old, neutered male cat. A biopsy sample was taken from the lesioned area with the suspicion of neoplasia and sent to the pathology laboratory in the case, which had been present for about 4 months and was taken for clinical examination when it started to grow rapidly. The biopsy specimen was fixed in 10% formalin solution for 24 hours. Then, the tissue sample was embedded in paraffin blocks after routine tissue follow-up procedures. Sections of 3-4 μm thickness were taken from paraffin blocks and stained with Hematoxylin-Eosin. Squamous cell carcinoma was diagnosed histopathologically in the analyzed biopsy specimen (VetLab, Veterinary Diagnostic Laboratory). Immunohistochemical marking was performed with Cytokeratin, Vimentin, and Ki67 antibodies to determine the differential diagnosis and prognosis. In the histopathological examination of the case, neoplastic cells were also observed in the surgical margins, and the tumoral mass was removed with an operative intervention with a deeper and wider margin and closed with a flap from the non-lesional tissues. Computed tomography (CT) imaging of the case, which did not have any complications during the post-operative recovery period, was performed. Radiation therapy was also planned for the case whose metastasis findings were not observed during CT examination. Our case diagnosed with SCC, which has an aggressive course for cats, was treated with the principle of stereotactic body radiation therapy (SBRT), in the form of 3 fractions of 24 Gy in total, to the tumoral area.
FINDINGS
In the clinical examination of the case, mainly ulcerated and erosive areas were observed in and around the nasal region, including the nasal cavity. A proliferating, keratinized, and bleeding neoplastic lesion was observed in the left nasal cavity (Figure 5).
It was determined that the obstruction caused by the lesioned area caused the stertor symptom. In order to take a biopsy from the neoplastic lesion, complete blood count and serum biochemistry were examined in the hematological examination before general anesthesia. With operative intervention, two dark-colored, amorphous soft tissue samples with dimensions of 1×0.8×0.5 cm and 0.6×0.5×0.3 cm were taken and sent to the pathology laboratory. In the tissues examined histopathologically, it was observed that atypical epithelial cells with vesicular nuclei, narrow cytoplasm, and some multinucleated epithelial cells, which started at the border of the destroyed epithelial layer, proliferated and spread towards the subcutis. Anisocytosis, anisokaryosis, and mitotic figures were detected in epithelial cells. Although proliferating cells formed islands, keratin lamellae were observed between these cells (Figure 1).
In addition, infiltrations of polymorphic neutrophil leukocytes and mononuclear inflammatory cells were predominant among the neoplastic islands. The histopathological examination revealed Squamous Cell Carcinoma. Besides that, neoplastic cells were detected at the surgical margin (Vetlab,Veterinary Diagnostic Laboratory). Neoplastic cells were labelled with Cytokeratin, Vimentin and Ki67 antibodies using the immunohistochemistry working principle used in the differential diagnosis. Intracytoplasmic and perinuclear immunopositive responses were observed against Cytokeratin in squamous neoplastic cells (Figure 2), while the same areas were negative with Vimentin (Figure 3). The proliferation index of the neoplasia was determined as advanced by Ki67 staining (Figure 4).
TREATMENT
Due to the local aggressiveness of the case with SCC and the high probability of recurrence, an operation was planned with a deep and wide margin surgically. Under general anesthesia, the lesioned areas were removed and aesthetically reconstructive surgery was performed on the area with a tissue flap (Figures 6, 7, and 8).
No complications were observed in the wound healing and general condition of the patient, whose pain management and regular controls were performed during the post-operative care process. Approximately 2 months after the patient’s surgical treatment, a 3-cm margin was determined around the contouring and target volume during the CT scan, in order to plan the radiation therapy. Target volumes were subtracted from contours containing organs at risk to meet normal tissue optimization constraints. A 24 Gy SBRT protocol was created in 3 fractions for the case[3]. Immobilization was performed with a thermoplastic mask under general anesthesia (Figure 9). Hematological and biochemical values were checked regularly before each radiation therapy (IDEXX Catalyst Dx® Biochemical Analyzer, IDEXX ProCyte® Hematology Analyzer).
CONCLUSION- DISCUSSION Nasal SCC in cats is a relatively common carcinoma with a locally aggressive course and high recurrence rate. Both the surgical difficulty of total removal due to its anatomical location and the aggressive course of nasal tumors in cats always cause a challenge in treatment. Current treatments that have been applied recently are still in the trial phase. However, as a current approach, radiotherapy has been preferred by veterinary oncologists due to its good tolerance and successful treatment method in SCC tumors. The biggest advantage of SBRT, one of the modern irradiation protocols, compared to traditional radiation therapy protocols is that it takes shorter treatment time, creates less anesthesia time, and shows superior results, especially in anatomically inaccessible tumors. We believe that SBRT and radiotherapy treatment will become widespread in terms of veterinary oncology in the coming years and will contribute to literature research in this field. REFERENCE [1] Goldschmidt H.M., Goldschmidt H.K. Epithelial and Melanocytic Tumors of the Skin. In: Meuten D, ed. Tumours in Domestic Animals. Ames, IA: John Wiley; 2017: 97-99 [2] Potters L., Steinberg M., Rose C., et al. American Society for Therapeutic Radiology and Oncology and American Col lege of Radiology practice guideline for the performance of stereotactic body radiation therapy. Int J Radiat Oncol Biol Phys 2004; 60: 1026–1032. [3] Swan B. M., Morrow B. M., Lurie M. D. Pilot study evaluating stereotactic body radiation theraphy for feline facial squamous cell carcinomas. Journal of Feline Medicine and Surgery 2021 23(12):1081-1088.
