Melanotic Melanoma in a ۱۳-years-old female German shepherd dog Histopathological and Case Study

Background: Melanoma is a kind of skin tumor that starts in the melanocytes which produced pigment from melanosome. Malignant tumor of melanocytes called Melanoma and benign forms named Melanocytoma. It happened in middle-aged to older aged dogs and frequently exist in extremely pigmented breeds. While oral and cutaneous melanoma is the most prevalent form, the existence and incidence of these tumors subject of debate in the literature. Most effective treatment for melanoma is surgery. This report describes an occurrence of Cutaneous melanotic melanoma in a ۱۳-years-old female German shepherd dog that was referred to the small animal hospital with pigmented mass on trunk region. Methods: After clinical examination, the animal was referred to the surgical department for biopsy. The mass was completely removed and submitted to the diagnostic pathology. Histopathologic evaluation revealed clusters and nests of melanocytes with variable size and shape in dermis. Neoplastic cells showed moderate pleomorphism. Melanin pigment was abundant in cytoplasm of melanocytes. A few mitotic figures were present too. Mild infiltration of tumor cells into the subcutis were seen. IHC staining indicated strong cytoplasmic positivity for Mean-A and strong nuclear staining for SOX۱۰ that confirmed Malignant Melanotic melanoma (Moderately differentiated). Results: This report aims to provide a precise diagnosis and a thorough description of histopathological features of cutaneous melanotic melanoma by IHC staining to differentiate it from other neoplasms with a similar macroscopic appearance. In our case, according to H&E and IHC evaluation, wide margin surgical excision was performed and short-term follow- up was conducted. Conclusion: Melanoma is aggressive tumor, in this regard complete surgical excision with wide margins is treatment of choice. With involvement of muscles, the risk of recurrence is high and chemotherapy is recommended.

کلیدواژه ها:

Melanotic melanoma ، Cutaneous ، Dog ، Histopathology