Histopathological and IHC evaluation of malignant non-pigmented chromatophoroma in a savannah monitor (Varanus exanthematicus)

Chromatophoromas are neoplasms arising from pigment cells (chromatophores) and commonly manifest as cutaneous lesions. While brown to black melanophoromas are most prevalent in reptiles, sporadic cases of non-pigmented chromatophoromas have been reported. This case study documents the clinical presentation, histopathological features and IHC (IHC) profile of an oral non-pigmented chromatophoroma in a 13-year-old male savannah monitor (Varanus exanthematicus). Histopathological examination revealed a poorly demarcated tumour located in the mucosa. Non-pigmented neoplastic cells with marked anisocytosis, anisokaryosis, increased nuclear-cytoplasmic ratio and numerous mitotic figures formed solid packets separated by collagenous septa. IHC analysis revealed that tumour cells were positive to melan-A, S100 protein, neuron-specific enolase and cytokeratins AE1/AE3. Based on the histopathological and IHC findings, the tumour was diagnosed as a non-pigmented chromatophoroma. Detailed histopathological and IHC profiling enhances our comprehension of the diversity within chromatophoromas and underscores the diagnostic complexities involved. Immunohistochemistry is a crucial tool for identifying non-pigmented chromatophoromas.