Malignant Mixed Chromatophoroma with Cutaneous, Pulmonary, and Testicular Metastases in a Veiled Chameleon (Chamaeleo calyptratus)
A 6-year-old male veiled chameleon (Chamaeleo calyptratus) was presented for mass removal on the right mandible. Histopathology revealed an iridophoroma, a subclassification of chromatophoromas. Several months later the chameleon was euthanized and the necropsy, combined with histopathology, indicated metastasis of a mixed chromatophoroma within the skin and to the lungs and testicle. The tumor was further subclassified as a mixed iridophoroma and xanthophoroma based on ultrastructure. Other pathologic findings included marked hepatic fibrosis and severe biliary hyperplasia and severe bilateral cystic glomerulopathy. This case demonstrates the malignant potential of chromatophoromas in chameleons and highlights the need for ultrastructural examination of these tumors for proper subclassification.Abstract
Two yellow-orange nodular cutaneous masses (arrows) measuring 0.75 cm and 0.3 cm on the right side of the body.
Multiple, 0.1- to 0.4-cm-diameter yellow-orange masses (arrows) in the lung.
Cutaneous chromatophoroma composed of two cell populations: spindle cells containing olive-green to brown cytoplasmic pigment (arrow) are interspersed with large polygonal cells with eosinophilic cytoplasm (arrow head). H&E, X 40.
Cutaneous chromatophoroma under polarized light demonstrating birefringence of the pigmented spindle cells. H&E, X 40.
Transmission electron micrograph of the neoplastic pigmented cells showing a latticework of electrolucent spaces in the cytoplasm. Bar = 1 micron (μ).
Transmission electron micrograph of the neoplastic polygonal cells showing lamellated pterinosomes (arrows). Bar = 1 micron (μ).
