Ovarian Sex Cord Stromal Tumor in a Free-Ranging Brown Bear ( Ursus arctos )

• Published in: Animals
• Main Authors: Natalia García-Álvarez, Álvaro Oleaga, María José García-Iglesias, Claudia Pérez-Martínez, Daniel Fernández, Luis Miguel Álvarez, Ramón Balsera, Ana Balseiro
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2024
• Subjects: brown bear ( Ursus arctos ); sex cord stromal tumor; steroid cell tumor; ovary; pathology; immunohistochemistry; Veterinary medicine; SF600-1100; Zoology; QL1-991; Ursus arctos
• Online Access: https://doi.org/10.3390/ani14131936; https://doaj.org/article/8b0e931ec41b4ad9a2698178c816e6c0

Reports on neoplasms in bears are scarce, especially concerning ovarian tumors. A large primary ovarian neoplasm with multiple metastasis was found during the necropsy of a 14-year-old free-ranging Eurasian brown bear ( Ursus arctos ) from Northwestern Spain. Histopathology and immunohistochemistry allowed for the diagnosis of a sex cord stromal tumor. This is a complex group of neoplasms which differ in the predominant cell morphology and immunohistochemical features. The microscopic examination revealed two types of cells, one with eosinophilic cytoplasm, intermingled with larger vacuolated cells rich in lipids. The evaluation of the immunoreactivity to different markers, frequently used in the characterization of gonadal tumors (INHA, inhibin-alpha; PLAP, placental alkaline phosphatase; Ki-67; α-SMA, actin alpha-smooth muscle) and inflammation patterns (IBA1, ionized calcium-binding adapter molecule for macrophages; CD3 for T lymphocytes; CD20 for B lymphocytes), displayed significant INHA positive immunostaining of neoplastic cells, as well as inflammatory cell infiltration, mainly composed of macrophages and B lymphocytes. These findings were consistent with a malignant ovarian steroid cell tumor, not otherwise specified. The present study characterizes an unusual type of neoplasm, and also represents the first report of an ovarian sex cord stromal tumor in Ursidae .