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Background: Melanoma is a malignant neoplasm that arises from melanocytes and malanoblasts. It is also more frequently reported in dogs than in other species. They may arise from melanocytes in the skin, on the surfaces of the mucous membranes, and eyes. The aim of this study was to describe the epidemiological aspects, risk factors and clinicopathological findings of melanoma in dogs in the backlands, northeastern Brazil. Materials, Methods & Results: A retrospective study was carried out in all biopsy samples and necropsy examinations of dogs, from January 2003 to December 2021, at the Animal Pathology Laboratory of the Federal University of Campina Grande, Patos, Paraiba, northeastern Brazil. Epidemiological data, clinical signs, and gross lesions were reviewed from the diagnostic laboratory reports. Samples of the skin, lymph nodes, central nervous system and organs of the thoracic and abdominal cavities were fixed in 10% buffered formalin, processed routinely for histopathology, embedded in paraffin wax, cut into 4 µm sections, and stained with hematoxylin and eosin (HE). Histological sections were also submitted to immunohistochemistry with the primary antibody anti-Melan A. Of the 4717 records found, 1158 (24.5%) were diagnosed with neoplasms, of which 48 (4.14%) cases were of melanoma. Of this total, 28 (58.3%) dogs were elderly, 19 (39.6%) were adults, and 1 (2.1%) was young. Mixed breed animals were the most affected (42.6%), followed by the pinscher breed (19.1%). According to the anatomical region, the most affected site was the skin (38/53=71.7%), followed by the oral cavity (12/53=22.65%) and the eyes (3/53=5.7%). Grossly, the skin lesions were characterized by exophytic and usually blackened, sometimes irregular and firm, nodules. At cut, they had a smooth, compact and blackened surface. Lesions in the oral cavity were characterized by blackened, irregular and infiltrating nodules or masses. The ocular lesions were always unilateral and were characterized by an enlarged and diffusely blackened eyeball, with areas of ulceration and subversion of tissue architecture. In 5 animals there was more than one anatomical site affected, totaling 53 lesions. In 9 (17%) cases, metastases were identified, 8 in regional lymph nodes and 1 in the lung. Histopathology showed a densely non-encapsulated, poorly delimited, expansive and infiltrative neoplasm, composed of neoplastic cells arranged in islands or nests and supported by fibrovascular stroma, containing a variable amount of brownish pigment (melanin). Immunohistochemistry showed strong immunostaining of the neoplastic cells in brown by the anti-Melan A antibody. Discussion: The diagnosis of melanoma was established based on epidemiological, clinical, anatomopathological, and immunohistochemical findings. Gender is not a predisposing factor, and although there was no statistically significant relationship, males were more affected. Senescence is a conditioning risk factor. Elderly animals were more affected (P < 0.0001) than adult ones, with OR = 4.38; and young ones (P = 0.0051), with OR = 12.65. Some breeds, especially those with marked skin pigmentation, were more affected, however the most affected ones in this survey were pinscher and poodle. Cutaneous melanoma accounted for almost 72% of cases, contesting recent studies where oral cavity melanoma was more frequent. Therefore, it is believed that the climatic conditions of the backlands sub-region, in northeastern Brazil, associated with the individual characteristics of the dogs, are involved in the development of these neoplasms, since the climate is predominantly dry, with high temperatures throughout the year, with maximums that can reach 40ºC, favoring the exposure to high incidence of ultraviolet radiatio [ABSTRACT FROM AUTHOR]

Introduction: Melanocytic lesions may present with several histologic features that make them impossible to classify in a dichotomous way, as benign or malignant. Such lesions, designated as melanocytic proliferations of uncertain malignant potential, frequently show borderline features between benign nevus and malignant melanoma, reflecting their undetermined biological potential. Methods: In order to characterize melanocytic proliferations of uncertain malignant potential diagnosed at our center between 2007 and 2017, histopathological reports of melanocytic lesions classified, in this period, as either dysplastic or malignant were analyzed. Results: Twenty-three lesions (4.3%) with borderline histopathological features or uncertain malignant potential were identified. The mean patient age was 34.8 years. Sixteen lesions (69.6%) were observed by a second pathologist, with an inter-observer disagreement on 25%. The most frequently performed treatment was wide excision, with large variability regarding the surgical margins. A sentinel lymph node biopsy was performed in two patients, both being negative. The median follow-up time was 22 months, and there was no recurrence of any treated lesion. Conclussion: The controversy of this subject extends from the nature and classification of these lesions to their treatment. With this study we were able to verify the variability regarding their histologic characterization, as well as their treatment. However, the inexistence of recurrences and deaths attributable to the disease corroborates their frequently benign character and excellent prognosis. [ABSTRACT FROM AUTHOR]

Introduction: Dermoscopy is an in vivo, non-invasive technique that is widely used as a complementary method for the study of pigmented skin lesions and enables the early diagnosis of cutaneous melanoma. The purpose of the present study is to evaluate the diagnostic accuracy of dermoscopy and to extend the dermoscopy-histopatholoy correlations. Methods: Retrospective study using the database of the Dermoscopy and Pigmented Lesions Clinic and the database of the Histology of the Dermatology Department of CHUC. Each melanocytic lesion was evaluated according to multiple dermoscopic and histopathological parameters. The agreement between diagnoses and between the evaluated parameters was determined. Results: The malignant/benign ratio was 1:9.2. The agreement between the dermoscopic and histologic diagnoses was fair. The agreement for melanoma was excellent and dermoscopy showed 92.9% sensitivity and 96.9% specificity for this diagnosis. There was agreement between a reticular pattern and the presence of bridging of rete ridges and cytological atypia; globular pattern and the presence of nests; atypical network and presence of fibrosis and cytological atypia; blotches and pigmented parakeratosis; blue-whitish veil and fibrosis. Conclusion: In spite of some limitations and unexpected findings, many of the results of the present study are concordant with the literature, showing a high sensitivity and specificity of dermoscopy in the diagnosis of melanoma, which results in improvement in early diagnosis without increasing the total number of excisions of pigmented lesions. [ABSTRACT FROM AUTHOR]