Endolymphatic Sac Tumor in Two Dogs.
Endolymphatic sac tumors (ELSTs) are rare neoplasms of the inner and middle ear described in humans. Diagnosis of such neoplasms is difficult and largely dependent on a combination of histologic, immunohistochemical, and clinical findings. Although the neoplastic cells lack cellular features of malignancy, these are clinically aggressive tumors that often invade the surrounding temporal bone. Here, we describe 2 dogs with middle ear masses that share morphologic, immunohistochemical, and clinical similarities with human ELSTs. Advanced imaging of the masses revealed evidence of aggressive behavior such as bony lysis of the temporal bone. Histologically, the neoplastic epithelial cells formed papillary structures, lacked mitotic figures, and had mild anisocytosis and anisokaryosis. The neoplastic cells were immunohistochemically positive for cytokeratin AE1/AE3 but were negative for chromogranin, synaptophysin, and thyroglobulin. Local invasion and bone destruction but no evidence of metastases suggest a clinical behavior similar to human ELSTs.
1 Diagnostic Center for Population and Animal Health, Michigan State University, Lansing, MI, USA.
K J
KJ
Barnes
2 College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
V
V
Clear
3 The Small Animal Surgeon Ltd, Wattle Downs, Auckland, New Zealand.
K
K
Youmans
4 Gribbles Veterinary Pathology Ltd, Auckland, New Zealand.
M R
MR
Hardcastle
2 College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
N
N
Nelson
2 College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
A
A
Petersen
1 Diagnostic Center for Population and Animal Health, Michigan State University, Lansing, MI, USA.|5 Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
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M
Kiupel
D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis / Q000473:pathology*; D004285:Dogs; D004428:Ear Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D007758:Ear, Inner / Q000473:pathology; D004712:Endolymphatic Sac / Q000473:pathology; D005260:Female
adenocarcinoma; dogs; endolymphatic sac; inner ear; labyrinth diseases; neoplasia