Sporadic naturally occurring melanoma in dogs as a preclinical model for human melanoma.
Bottom Line: The spectrum of canine melanocytic neoplasia includes benign lesions with some analogy to nevi, as well as invasive primary melanoma, and widespread metastasis.Canine and human mucosal melanomas appear to harbor BRAF, NRAS, and c-kit mutations uncommonly, compared with human cutaneous melanomas, although both species share AKT and MAPK signaling activation.We conclude that there is significant overlap in the clinical and histopathological features of canine and human mucosal melanomas.
Affiliation: Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.Show MeSH
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Mentions: No well-recognized classification scheme exists for mucosal melanomas from either species; therefore, evaluation included review of melanoma features previously documented (Goldschmidt and Hendrick, 2002; Patel et al., 2002; Pfister et al., 2012; Prasad et al., 2004; Smedley et al., 2011b). The salient histopathological features of mucosal melanoma were tabulated for both species (Table S2). Near universal concordance of these features was observed between canine and human melanoma (Table S2). Analogous architectural features important for diagnosing and staging melanoma were noted in both species (Figure 1). As recognized for cutaneous melanomas, both human and canine mucosal melanomas included the range of epithelioid, spindloid, mixed epithelioid/spindloid, or small round blue cell melanocyte morphologies. Some dog specimens included a lentiginous-like growth pattern within stratified squamous mucosal epithelium and a significant radial growth phase involving mucosal epithelium flanking the vertical growth phase (Figure 2). By the time of clinical recognition, mucosal melanomas are typically advanced with considerable local invasion, ulceration, focal necrosis, and even metastasis, particularly in the dog. In both species, there was considerable pleomorphism with significant variation in cell and nuclear size, shape, and presence of nucleoli (Figure S1 and Table S2). Given the substantial difference in incidence between various anatomic sites, the board chose not to compare frequencies of all features.
Affiliation: Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.