Background
A significant increase in the incidence of neoplasms in wild animals maintained in captivity has been noted in recent years. Histiocytic sarcomas comprise a rare malignant macrophage-dendritic cell lineage neoplasm in wildlife. In this context, this study reports a rare case of histiocytic sarcoma in the small intestine of a collared peccary (Pecari tajacu), describing its clinical, anatomopathological, and immunohistochemical aspects.
Case presentation:
A six-year-old male collared peccary maintained in captivity at a facility in Northeastern Brazil presented progressive weight loss, diarrhea, anorexia, dyspnea, lethargy, abdominal distension, bristled fur, and pale mucous membranes. After 18 days, the animal was found dead in its enclosure. A pathoanatomical examination revealed that the animal exhibited poor body condition, scant body fat with a gelatinous appearance, hydrothorax, pulmonary edema, and excessive abdominal cavity fluid accumulation. Small intestine wall thickening was observed, along with the presence of a tumor mass in the duodenal portion. A histopathological examination of the affected intestinal segment indicated the presence of round neoplastic cells with giant, hypercolored nuclei, prominent nucleoli, and a high mitotic count (20 figures per field). Giant, binucleated, and multinucleated cells were also observed. The neoplastic cells infiltrated all histological layers, from the mucosa to the serosa. An immunohistochemical examination displayed strong positivity for CD18 and negativity for CD3 and CD79, confirming a histiocytic intestinal sarcoma diagnosis. Additionally, a Ki-67 index of 70% was recorded.
Conclusions
The determined histopathological characteristics and detection of specific immunohistochemical markers confirmed metastatic intestinal histiocytic sarcoma in a P. tajacu, a rare neoplasm described for the first time in this species.
