Multisystemic eosinophilia resembling hypereosinophilic syndrome in a colony-bred owl monkey (Aotus vociferans)

Abstract

In animals, multisystemic eosinophilic disease is a rare condition characterized by eosinophilic and lymphoplasmacytic infiltrates in various organs. This disorder resembles the human disease known as hypereosinophilic syndrome, a condition defined by prolonged peripheral eosinophilia in the absence of recognizable etiology and associated with end-organ damage. In this report we describe a research-naïve, colony-born, juvenile female owl monkey (Aotus vociferans) who presented clinically with severe respiratory distress and histologically with multiple end-organ infiltration with phenotypically mature eosinophils, plasma cells, and lymphocytes. No tumors or infectious agents were noted either macroscopically or microscopically. Cultures from lung samples revealed no bacteria or fungi. Histologic examination of lung, heart, thymus, liver, spleen, kidney, adrenal, pancreas, stomach, small intestine, and colon revealed no migrating nematode larvae, other parasites, or foreign material that might trigger eosinophilia, nor was there any evidence of or history consistent with an allergic etiology. Given that we ruled out most exogenous and endogenous triggers of eosinophilia, the signs, symptoms, and pathologic findings support the diagnosis of multisystemic eosinophilic disease. To our knowledge, this report is the first description of presumptive hypereosinophilic syndrome in a nonhuman primate.

Figure 1.

Aotus vociferans. Lung. Bronchus. Small aggregates of mature eosinophils, plasma cells, and lymphocytes are present between the cartilage and muscularis. Hematoxylin and eosin stain; magnification, ×1000.

Figure 2.

Aotus vociferans. Lung. Marked perivascular and peribronchial edema (asterisk) and peribronchial cellular infiltrate (arrows). Hematoxylin and eosin stain; magnification, ×40.

Figure 3.

Aotus vociferans. Small intestine. Large numbers of mature eosinophils, plasma cells, and lymphocytes diffusely scattered in the submucosa, lamina propria, and mucosa. Hematoxylin and eosin stain; magnification, ×400.

Figure 4.

Aotus vociferans. Pancreas. Region of the pancreas adjacent to the duodenum showing extensive coagulative necrosis. Hematoxylin and eosin stain; magnification, ×40.

Figure 5.

Aotus vociferans. Kidney. Mature eosinophils infiltrating the corticomedullary junction. Note the renal tubular epithelial necrosis and protein deposits in the Bowman capsule space. Hematoxylin and eosin stain; magnification, ×400.

Figure 6.

Aotus vociferans. Kidney. Mature eosinophils in glomerulus (arrowheads). Hematoxylin and eosin stain; magnification, ×1000.

Figure 7.

Aotus vociferans. Small intestine. Lamina propria. Eosinophils undergoing degranulation (arrow) next to a crypt (arrowhead). Hematoxylin and eosin stain; magnification, ×1500.