Histologic, immunohistochemical, and electron microscopic characterization of a malignant iridophoroma in a dwarf bearded dragon (Pogona henrylawsoni)

de Brot, Simone; Sydler, Titus; Nufer, Lisbeth; Ruetten, Maja

Abstract

A dwarf bearded dragon (Pogona henrylawsoni) was presented with a whitish subcutaneous mandibular mass and multiple nodules in the oral mucosa, heart, liver, kidney, intestine and visceral fat. Histologically, the tumor consisted of densely packed spindle-shaped cells with brownish intracytoplasmic pigment that exhibited white-bluish birefringence with polarized light. Immunohistochemical staining was negative for S-100 and weakly positive with Melan A. Negative contrast electron microscopic examination revealed cytoplasmic irregular, oblong empty spaces, laminated and often arranged into short stacks, compatible with reflecting platelet profiles typically seen in iridophores. However, in unstained ultrathin sections, electron dense crystalline material was present which filled the empty spaces described for stained sections before. Based on histology, immunohistochemistry and biological behavior, a malignant iridophoroma was diagnosed. To the authors’ knowledge, iridophoromas in lizards have not been characterized before by using electronic microscopy. Moreover, this is the first description of an iridophoroma in a dwarf bearded dragon.

Citation

de Brot, S., Sydler, T., Nufer, L., & Ruetten, M. (2015). Histologic, immunohistochemical, and electron microscopic characterization of a malignant iridophoroma in a dwarf bearded dragon (Pogona henrylawsoni). Journal of Zoo and Wildlife Medicine, 46(3), https://doi.org/10.1638/2013-0113.1

• Journal Article Type: Article
• Acceptance Date: Sep 1, 2015
• Publication Date: Sep 1, 2015
• Deposit Date: Feb 24, 2017
• Journal: Journal of Zoo and Wildlife Medicine
• Print ISSN: 1042-7260
• Electronic ISSN: 1937-2825
• Publisher: American Association of Zoo Veterinarians
• Peer Reviewed: Peer Reviewed
• Volume: 46
• Issue: 3
• DOI: https://doi.org/10.1638/2013-0113.1
• Keywords: Chromatophoroma, Dwarf bearded dragon, Electron microscopy, Iridophoroma, Pogona henrylawsoni
• Public URL: https://nottingham-repository.worktribe.com/output/758212
• Publisher URL: http://www.bioone.org/doi/10.1638/2013-0113.1