Immunohistochemical and morphological features of a small bowel leiomyoma in a black crested macaque (Macaca nigra)

The present study is related to a case of an intestinal leiomyoma in a black crested macaque (Macaca nigra), kept on captivity by Mateca？a Zoo, Pereira City, Colombia. The animal had abdominal distension, anorexia, vomiting, diarrhea and behavioral changes. Clinical examination showed an increased volume in the upper right abdominal quadrant caused by a neoplastic mass. The patient died during the surgical procedure. Necropsy revealed several small nodules in the peritoneum with adhesion to different portions of the small and large intestines, liver, stomach and diaphragm. Tissue samples were collected, routinely processed and stained by H&E. Microscopic examination revealed a mesenchymal tumor limited to tunica muscularis, resembling normal smooth muscle cells. Neoplastic cells were positive for alpha-smooth muscle actin and vimentin, and negative for cytokeratin AE1/AE3 by immunohistochemistry. Those morphological and immunohistochemical findings allowed to diagnose the intestinal leiomyoma referred above.Neoplastic diseases in primates have multifaceted causes. Their manifestations are understudied, leading to a greater difficulty in detection and measurement of the real impact provides by this disease.According to some surveys, Spontaneous gastrointestinal neoplasm in non-human primates is the most common tumor described in literature, accounting for up to 48.8% of the cases [1]. The disease is commonly seen in aged animals [2,3] which has caused an increasing scientific interest, in terms of comparative oncology studies, due to genetic similarities between human and non-human primates [1].Intestinal adenocarcinoma is the most prevalent tumor reported in primates belonging to Macaca genus [1], constituting a substantial cause of morbidity and mortality in the elderly [4]. However, other kind of tumor such as schwannoma [5], gastrointestinal stromal [6,7], leiomyosarcoma [8] and a poorly differentiated sarcoma [9], were also reported.Leiomyoma, after adenoma, is