Abstract

Background:
This report describes a case of uterine leiomyoma and cystic endometrial hyperplasia in an Asian elephant (Elephas maximus).

Case Description:
A 74-year-old female elephant in captivity was necropsied. At necropsy, the uterus was markedly enlarged, and a firm, white nodule measuring 10 × 10 × 8 cm protruded from the uterine wall into the lumen of the right uterine segment. Additionally, multiple cystic dilations (0.5–4 cm in diameter) were observed throughout the uterine segment. The mucosa was diffusely red with a moderate amount of crumbly clots in the lumen. Histologically, a benign mesenchymal neoplastic proliferation composed of multidirectional bundles of muscle tissue expanded the uterine muscular layer. The mucosa exhibited cystic dilations lined by simple squamous epithelium. In Masson’s trichrome staining, the neoplastic cells showed intense red staining, consistent with muscle tissue, whereas blue staining was restricted to the supporting fibrous connective tissue. Immunohistochemistry revealed mild cytoplasmic vimentin staining, moderate desmin immunoreactivity, and strong smooth muscle actin expression in neoplastic cells. Based on the anatomopathological, histochemical, and immunohistochemical findings, uterine leiomyoma and cystic endometrial hyperplasia were diagnosed.

Conclusion:
This case highlights the importance of diagnosing neoplasms and other conditions in captive elephants to better understand the diseases affecting these animals.

Key words: Megavertebrates; Neoplasm; Uterus; Zoo.