Coristoma ósseo mesentérico em uma porca / Mesenteric osseous choristoma in a sow

ABSTRACT

Background: Osseous choristomas represent the production of osseous tissue in abnormal regions, such as subcutaneous, fibrous or perivascular tissues, skeletal muscle and skin. These structures have been found in humans, dogs (lungs and dura mater), horses (large intestines) and cattle (lungs and mesenteric lymph nodes). They were also found in the mesenteric region and thoracic cavity of sows and piglets. The aim of this paper was to describe the macro and microscopic lesions found in a sow which died suddenly by a rare mesenteric osseous choristoma. Case A lactating sow, parity four, from the Swine Department of the Federal University of Rio Grande do Sul (UFRGS), Brazil, showed appetite loss, hyperthermia (41.5ºC) and sudden death. The animal was submitted to necropsy at the Department of Veterinary Pathology, UFRGS. On external examination, the sow showed conjunctival and perioral cyanosis, proximal colon region with a firm structure with approximately 3.0 cm length in mesenteric area. Moreover, the colon was ruptured and fibrin deposition and intestinal content in abdominal cavity were observed. Fragments of organs were collected in 10% formalin, routinely processed for histology and colored with hematoxylin and eosin stain (H&E). Histologically, it was found bone trabeculae with osteoid, periosteum, spaces with osteocids and endochondral ossification with bone marrow composed by adipose tissue and intense proliferation of conjunctive stroma. The mesenteric lymph nodes showed intense lymphoid hyperplasia with multifocal centrilobular necrosis. There was fibrin in serosa of colon, acute peri-spleen and acute fibrinopurulent perihepatitis. Discussion: Macroscopic and microscopic findings were consistent with mesenteric osseous choristoma. This condition is unusual in domestic animals, however it has been already described in pigs...