Document Type : Clinical Report

Authors

• Tomokazu Nagashima ¹
• Chisato Kishi ¹
• Yukino Machida ¹
• Masaki Michishita ²

¹ Department of Veterinary Pathology, Nippon Veterinary and Life Science University

² Nippon Veterinary and Life Science University

Abstract

A 16-year-old male mixed-breed dog presented with a mass with hemorrhage at the right conjunctiva. Five months after the initial visit, the right eye protruded and had a firm and irregular mass measuring approximately 1 cm in diameter with conjunctival hemorrhage. Microscopically, the mass was comprised polygonal or round tumor cells with distinct cell borders arranged in a nested and diffuse pattern. The tumor cells had round-to-oval fine hyperchromatic nuclei containing distinct multiple nucleoli and abundant eosinophilic or pale cytoplasm. Multiple giant cells were frequently observed. The mitotic index was 12.6/high power field. Extensive necrosis, hemorrhage and part of the cord-like or papillary epithelioid cells were observed in the intratumor tissue. Immunohistochemically, the tumor cells were positive for vimentin and α-smooth muscle actin and negative for cytokeratin, desmin and PNL2. On the other hand, the cord-like and papillary epithelioid cells were positive for vimentin, S100 and NSE. The tumor was diagnosed as an epithelioid leiomyosarcoma. This case considered to have occurred in the ocular region, although the ocular structure was destroyed.

Keywords

• Dog
• Epithelioid type
• Leiomyosarcoma
• Eye
• Smooth muscle actin

Main Subjects

• Pathology