Cutaneous melanoma in a red-footed tortoise (Chelonoidis carbonaria)

Chromatophoromas in Reptiles

“…Melanophoromas and iridophoromas are most common, with few reports of mixed chromatophoromas, xanthophoromas, and amelanotic or non-pigmented chromatophoromas [ 8 , 11 , 12 , 13 , 17 , 18 ]. Of the different reptilian orders, they are most frequently described in squamata with few reports in testudines (chelonia) and no reports in crocodilia or rhynchocephalia [ 9 , 11 , 12 , 13 , 14 , 19 , 20 , 21 ] Affected animals are almost always adults and no sex predilection is apparent [ 9 , 11 , 12 , 13 , 14 ]. Most reports are cutaneous chromatophoromas that develop as single or multiple masses at various sites, including the head, trunk, limbs (when applicable), and tail [ 9 , 12 , 13 , 22 , 23 ].…”

“…Cytologic examination, including fine needle aspirates and impression smears, can be a minimally invasive method to diagnose chromatophoromas. In a few reptile cases this diagnostic technique successfully identified the mass as a chromatophoroma [ 19 , 20 , 21 , 23 , 27 , 36 , 37 ]. In all these cases, the diagnosis was subsequently confirmed by histologic examination.…”

“…In all these cases, the diagnosis was subsequently confirmed by histologic examination. Cytologic findings using Romanowsky-type stains included discrete to aggregated stellate, spindloid, or round cells that contained scant to copious amounts of fine, intracytoplasmic dark blue to black granular material [ 19 , 20 , 21 , 23 , 27 , 36 , 37 ]. Neoplastic melanophores contained green, black, or brown melanin granules [ 19 , 20 , 21 , 27 , 37 ].…”

“…Cytologic findings using Romanowsky-type stains included discrete to aggregated stellate, spindloid, or round cells that contained scant to copious amounts of fine, intracytoplasmic dark blue to black granular material [ 19 , 20 , 21 , 23 , 27 , 36 , 37 ]. Neoplastic melanophores contained green, black, or brown melanin granules [ 19 , 20 , 21 , 27 , 37 ]. Neoplastic iridophores contained olive green or light brown refractile granules [ 23 , 36 ].…”

“…Intraepithelial neoplastic cells are only described in a small number of snake cases, which most likely represent epithelial invasion rather than junctional activity, as chromatophores do not reside in the epidermis in most reptiles [ 9 , 24 , 43 ]. Lymphatic invasion is uncommonly observed (7 out of 208 cases, when reported in the literature), even in cases that had widespread metastasis [ 9 , 12 , 20 , 21 ]. Neoplastic cells at metastatic sites typically have a similar histologic appearance as the primary neoplasm [ 9 , 12 , 17 , 19 , 37 ] ( Figure 5 a–e).…”