Diagnostic and Prognostic Challenges of Oral Melanoma in Dogs: A Literature Review and 2 Case Studies.

Oral melanoma is the most common maxillofacial malignancy in dogs. A unique characteristic of melanoma is its ability to mimic other oral tumors, which makes it one of the most challenging oral tumors to diagnose, especially since 30% to 40% of cases are amelanotic. This article presents 2 case reports of dogs with amelanotic oral melanoma that were both diagnostically challenging. Case 1 is a sparsely pigmented, spindle cell oral melanoma that was initially diagnosed as benign fibrous hyperplasia and subsequently suspected to be fibrosarcoma. Case 2 is an amelanotic oral melanoma that was originally diagnosed as an extramedullary plasmacytoma. This report highlights features of each of the cases while also discussing strategies to optimize the diagnosis of oral melanoma in dogs. A literature review summarizes the diagnostic evaluation of oral melanoma and how it pertains to prognostication.