Thymic epithelial tumor with heart metastasis in a horse.
Thymic malignancy is rare in horses. Thymic epithelial tumor was diagnosed in an 18-year-old mare with invasion and metastasis to the pericardium and heart. At necropsy, the cranial thoracic cavity was obliterated by a large mass located in the thymic region and the right atrium was also expanded and effaced by a similar mass. Histologically, the neoplasm was composed of sheets of spindle cells with intraparenchymal Hassall's corpuscles and formation of pseudorosettes around blood vessels compatible with type A thymic epithelial tumor according to World Health Organization classification. The neoplastic cells were diffusely immunoreactive for cytokeratin and negative for vimentin, S100, neuron specific enolase, glial fibrillar acidic protein, chromogranin A, synaptophysin, CD3 and CD79a markers. To the authors' knowledge, cardiac invasion and distinct histological pattern of pseudorosette formation have not been described in equine thymic epithelial tumors previously.
Shahriar
Farshid
F
California Animal Health and Food Safety Laboratory, San Bernardino Branch, University of California, Davis, 105 West Central Avenue, San Bernardino, CA 93408, USA.
Moore
Janet
J
Can Vet J. 2007 Aug;48(8):865-7
17824334
Equine Vet J. 1986 Sep;18(5):414-7
3769888
Curr Treat Options Oncol. 2008 Dec;9(4-6):288-99
19191029
Hematol Oncol Clin North Am. 2008 Jun;22(3):381-92
18514122
Vet Pathol. 1978 Mar;15(2):153-69
664184
Cancer Res. 1969 May;29(5):1146-50
5818671
J Am Vet Med Assoc. 1988 Aug 15;193(4):477-80
2844708
Aust Vet J. 1983 Feb;60(2):61
6301417
Am J Surg Pathol. 2002 Dec;26(12):1605-11
12459627
Vet Pathol. 1986 Sep;23(5):627-9
3776019
Nihon Juigaku Zasshi. 1987 Jun;49(3):577-9
3613360
Can Vet J. 1996 Mar;37(3):165-7
8681286
J Vet Diagn Invest. 2006 Sep;18(5):503-7
17037626
Natl Cancer Inst Monogr. 1969 Aug;32:121-51
4981714