Treatment of an Amelanotic Melanoma Using Radiation Therapy in a Lesser Madagascar Hedgehog Tenrec (Echinops telfairi)
American Association of Zoo Veterinarians Conference 2008
Tara M. Harrison1,2, DVM, MPVM; Pedro Dominguez2, DVM; Elizabeth McNiel2, DVM, PhD, DACVIM (Oncology), DACVR (Radiation Oncology); Kim Hanzlik1, DVM; James G. Sikarskie2, DVM, MS, DACZM; Dalen Agnew3, DVM, PhD, DACVP; Ingrid Bergin3, VMD, MS, DACLAM; Scott D. Fitzgerald3, DVM, PhD, DACVP, DACPV; Barbara Kitchell2, DVM, PhD, DACVIM (Internal Medicine and Oncology)
1Potter Park Zoo, Lansing, MI, USA; 2College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA; 3Diagnostic Center for Population and Animal Health, Michigan State University, East Lansing, MI, USA
Abstract
Neoplasia is commonly reported in insectivores.1-5 In this case, a 15-year-old male lesser Madagascar hedgehog tenrec (Echinops telfairi) presented with a mass caudal to the right ear. Cytology suggested a sarcoma. Surgical removal was attempted. Histologically, the mass resembled a soft tissue sarcoma. The mass recurred at 331 days post operation. Radiation therapy was initiated. Computed tomography was used for staging and, in conjunction with three-dimensional computerized treatment planning software, to permit accurate lesion localization and optimize normal tissue sparing. A total dose of 6480 cGy was administered in 24 fractions over 46 days. Transient hind limb paresis developed during the course of the radiation therapy, but resolved after 7 days with prednisone treatment. Minimal acute radiation toxicity was observed. The mass responded with at least a 90% reduction in volume following radiation treatment. The animal survived 266 days from the initiation of treatment. Lesions at necropsy consisted of a small residual mass and granulation tissue at the site of the initial neoplasm, indicating good local regional control of the tumor, but there were extensive metastases to the spleen and liver. Immunohistochemically, the original, recurrent, and metastatic populations were strongly positive for HMB 45 and weakly positive for S-100 and the final diagnosis was metastatic amelanotic melanoma.
Acknowledgments
The authors would like to thank Potter Park Zoo Keepers and staff, as well as Michigan State University’s College of Veterinary Medicine veterinarians, veterinary technicians, and students who assisted in this case. We would like to give a special thanks to Holly for performing anesthesia for this animal’s radiation treatments.
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