Ovarian tumors in mares are uncommon in comparison to other neoplasms and are classified into three categories: gonadal stromal tumors, coelomic epithelium surface tumors, and germinal cell tumors. Some ovarian neoplasms histologically show a mixture of multiple cell types in the same tumor, such as fibrothecoma; therefore, the differentiation between fibroma and thecoma is often difficult. According to the World Health Organization, fibrothecomas are classified as sex-cord stromal tumors (pure stromal tumors). Neoplasms such as fibrothecoma present with limited morphological, clinical, ultrasonographic, and endocrine profile characteristics. To diagnose this type of tumor, a broad clinical examination is needed, but histopathology remains the most accurate. Herein, we report a case of incidentally found ovarian fibrothecoma during a diagnostic laparotomy in a 6-year-old Dutch Warmblood (KWPN) mare who presented to the clinic with colic symptoms. After a unilateral ovariectomy, the altered right ovary was diagnosed as fibrothecoma based on histopathological features.

Ovarian tumors in mares are not common in comparison to other neoplasms and are divided into three categories: gonadal stromal tumors, coelomic epithelium surface tumors, and germinative cell tumors [12]. Some ovarian neo-plasms histologically show a mixture of multiple cell types in the same tumor, such as fibrothecoma, therefore the dif-ferentiation between fibroma and thecoma is often difficult [1]. According to World Health Organization, fibrothecoma is classified as sex cords stromal tumor (pure stromal tumor) [13]. Neoplasms, such as fibrothecoma have a very scarce morphology, clinical signs, ultrasonographic view and endocrine profile. To diagnose this type of tumor, a broad clini-cal examination is needed, but histopathology remains the most accurate. Herein, we report a case of incidentally found ovarian fibrothecoma during diagnostic laparotomy in 6-year-old KWPN mare which was presented to the clinic with colic symptoms. After unilateral ovariectomy, the altered right ovary, based on histopathological features was diag-nosed as fibrothecoma.