Current Insights Into Canine Cutaneous Melanocytic Tumours Diagnosis

Abstract

Cutaneous melanocytic tumours are most common in older dogs (mean age of 9 years old) [25], with a higher mean age for dogs with malignant melanocytic tumours (12 years). However, age has not been related with the patient clinical outcome and survival time [26].Although all breeds of dog (and crossbred animals) may be affected, some breeds are reported as predisposed, including Schnauzer, Doberman, Scottish Terrier, Irish Setter, Golden Retriever, Chow Chow, Cocker Spaniel, German Shepherd and Rottweiler [4,27]. Breed predisposition is thought to be related to an underlying genetic risk and/or increased pigmentation in the described above breeds [4].One study [6] has also established a relationship between patient breed and tumour behavior, likely due to genetic susceptibility, as prior described. In the referred work, melanocytic lesions tended to be behaviorally benign in Doberman pinschers and miniature schnauzers, while miniature poodles were the mostly affected breed with malignant melanoma. However, it must be noted that oral neoplasms were also included in that study.An early report described a higher frequency of these lesions in male dogs [28], but recent literature denies gender predisposition [6,27,[29][30][31].

Kynurenine 3‐monooxygenase (KMO), and signal transducer and activator of transcription 3 (STAT3) expression is involved in tumour proliferation and predicts poor survival in canine melanoma

“…The tumour location was identified as an important feature of canine melanoma in our study. The oral cavity (40%‐62%) and cutaneous (27%‐31%) locations were previously reported to be the most common sites of malignant melanoma, 1,28,29 and our results indicated that the oral cavity (68%) was the most frequently affected site (Table 1). Additionally, it was surprising that the expressions of KMO and STAT3 were significantly associated with a tumour location in the oral cavity (Table 4).…”

“…Melanocytic neoplasms have a high incidence in canines, and the most common location of canine malignant melanoma is reportedly the oral cavity 1 . Malignant melanoma is aggressive, grows rapidly, is locally invasive, and metastasizes to regional lymph nodes and distant sites, such as the lungs, heart and brain 2 .…”

“…The major treatment for both benign and malignant melanoma is surgical excision 3,4 . Melanomas with benign histopathologic criteria have a good prognosis after surgical resection, but for malignant melanoma, the prognosis is poor owing to a metastatic rate of 30%‐75% 1 . On the other hand, canine oral melanomas may initially be diagnosed as malignant based on histomorphology, but only 59% of these cases may show malignant behaviour 5 .…”

Cyclooxygenase-2 (COX-2) Expression in Equine Melanocytic Tumors

“…In the case of equine melanocytic tumors, there is a specific feature that can be related to COX-2 expression in benign tumors. In contrast to most canine melanomas that arise de novo, equine melanocytic tumors could have a time-dependent transformation of benign into malignant tumors [ 7 ]. The presence of COX-2 in benign tumors may promote this transition to malignancy.…”

“…Canine melanocytic tumors are also common, with the clinical course being related to tumor localization. Oral and mucocutaneous forms are usually highly malignant and invasive and often metastasize early in the disease course, being similar to human melanoma [ 2 , 7 , 8 ]. On the other hand, the cutaneous form more often presents a benign behavior.…”