1. Istanbul University-Cerrahpasa, Faculty of Veterinary Medicine, Department of Pathology, Buyukcekmece, Istanbul
2. Ada Veterinary Policlinic Sulun Sokak No: 14 1. Levent, Besiktas, Istanbul
3. Istanbul Bilgi University, Department of Radiation Oncology
Peripheral giant cell granuloma, formerly known as giant cell epulis, is one of the non neoplastic pathological conditions of gingiva and is a very rare condition encountered in pet animals. Histopathology is the diagnostic tool to eliminate similar lesions. The aim of this case report was to present this rare condition and its marked remission by radiotherapy and zoledronic acid (ZA) administration.
Material & Method
A 10-year-old, mixed, neutered, male cat was presented to the clinic with oral mass on mandible, emaciation due to feeding difficulty and salivation. On physical examination, an oral mass was observed on the rostral mandible. The mass was completely removed by surgical operation and was sent to pathology department for histopathological examination. The tissue sample was fixed in 10% formaldehyde solution, routinely proceeded and embedded in paraffin blocks. Tissue sections of 4-5 μm thickness were cut and stained with Hematoxylin and Eosin staining.
Macroscopic findings: The oral mass located on the rostral mandible was found 1X0.6X0.5 cm in size, in white-yellow color with an elastic consistency, and was characterized by superficial ulceration (Fig. 1 and 2).
Histopathological findings: Histopathological examination revealed superficial ulceration (Fig.3, star), hyperplasia of epithelial mucosa showing rete pegs (Fig. 4, arrows), severe infiltration of histiocytic cells admixed with numerous multinucleated giant cells of various shapes and sizes, (Fig.5) with fibrous stroma. In addition, bone involvement was significant (Figs. 6, 7). The case was diagnosed as peripheral giant cell granuloma.
The patient received 250.0 cGy / fractions of radiotherapy 3 days a week for 14 sessions during 48 days. Then the treatment continued to be pursued with zoledronic acid at 0.2 mg/kg diluted into 25 mL of 0.9% saline and administered as a 15-minute constant rate intravenous infusion once a month.
This rare clinical condition is found more predisposed in cats than other pet animals and presents an aggressive clinical course such as expansive osteolytic behavior, as seen in this case. In human medicine, ZA and radiotherapy are used as treatment options for PCGC. ZA provides the impairment of angiogenesis and bone destruction by decreasing serum concentration of VEGF and serum markers of bone lysis. A study has shown the positive effect of ZA administration in cats with bone-invasive oral squamous cell carcinoma. In this study, aggressive behavior of the condition was associated with the bone lysis and ulceration. Nonetheless, marked remission could be obtained by the administration of the radiotherapy and ZA combination. The choice of the treatment resulted in positive results as described in human medicine.
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