Epithelioid Cells in Mediastinal Lymph Nodes of Cattle without Cancer

Abstract

Abstract. Epithelioid cells are found in lymph nodes in cases of metastatic carcinoma; however, epithelioid cells with benign features have also been discovered incidentally in lymph nodes. Epithelioid cells were observed in mediastinal lymph nodes of cattle without cancer during routine diagnostic necropsy. To explain this finding, the authors evaluated the prevalence and histopathologic, immunohistochemical, and ultrastructural features retrospectively using mediastinal lymph nodes from 110 cattle and found that 66 of the lymph nodes contained epithelioid cells. In all 66 nodes, most of the epithelioid cells were individual or aggregated in nodal sinuses; in 21 nodes, some epithelioid cells formed tubular structures. The individual and aggregated epithelioid cells were mostly considered to be mesothelial in origin by immunohistochemical and ultrastructural examination; presumably, they entered the lymph nodes via lymphatic vessels, because they were found in afferent lymphatic vessels and nodal sinuses. Although the presence of epithelioid cells in lymph nodes prompts suspicion of metastatic carcinoma, the epithelioid cells in these bovine lymph nodes did not disrupt nodal architecture, lacked atypia or mitotic figures, and did not invade nodal parenchyma.

Detection of Ectopic Intestinal Epithelium in an Ileocaecal Lymph Node from an Adult Crossbred Aberdeen Angus Cow

“…In a previous report, it was described the presence of epithelioid cells (associated to metastatic carcinoma) in lymph nodes from healthy cattle, which were distributed as tubular or papillary structures in dilated sinuses [9]. These changes could be considered similar to those described in the present report.…”

“…Epithelial choristoma was previously diagnosed in a mesenteric LN from a goat, and in mediastinal LN from cattle [7,9]. In those cases, authors described the presence of the ectopic-non neoplasic epithelium, but the presence of secreted material by cells, as it occurred in the present case, was not referred.…”

“…All choristomas detected in LN were diagnosed in animals, which were positive for TB [7,9]. However, there has not been described a relationship between M. bovis infection and the development of choristoma.…”