Encephalitozoon pogonae–Associated Systemic Vasculitis in a Central Bearded Dragon (Pogona vitticeps)
A 4-yr-old female central bearded dragon (Pogona vitticeps) with a history of tenesmus was found dead 1 month after surgical debulking of a palpable caudal coelomic mass. At necropsy, a 2.5-cm-diameter, firm, lobulated, tan–yellow mass was associated with the wall of the pelvic canal and bilateral masses were present in the caudal pharynx (0.6 and 3.0 cm in diameter), the largest of which was soft and dark red. Histologically, the mass within the pelvic canal arose from the coelomic wall and consisted primarily of fibrocollagen with myxoid to cystic regions, and mixed inflammatory infiltrates. Additional findings included granulomatous dermatitis, myositis/cellulitis, coelomitis, encephalitis, and pneumonia. Vasculitis was detected in multiple organs, and in the pharynx resulted in aneurysmal dilation and perivascular hemorrhage leading to masslike lesions. Within all lesions, scattered macrophages contained oval, weakly basophilic, Gram-positive, slightly refractile, 1–2 µm-diameter ovoid organisms consistent with microsporidia. A diagnosis of systemic microsporidiosis characterized by lymphohistiocytic and heterophilic vasculitis with medial hypertrophy and fibrinoid necrosis was made. Using DNA sequencing, the organism was identified as Encephalitozoon pogonae. Encephalitozoon pogonae should be considered a differential diagnosis for vasculitis and aneurysms in bearded dragons.Abstract
Tongue and orpharynx of a central bearded dragon (Pogona vitticeps). A raised, lobulated, smooth red mass is present in the pharyngeal mucosa on the right side (white arrows). On the left side, a smaller lobulated, smooth, white–tan mass is present (black arrow).
Coelom of a central bearded dragon (Pogona vitticeps). Clumps of yellow exudate are present in the coelom (arrowheads). A mass arises from the left body wall in the pelvic region (arrow). The mass is tan, smooth, irregular, and compresses the left kidney.
Mass from the left pharynx of a central bearded dragon (Pogona vitticeps). The mass is composed of multiple inflamed and dilated arteries (asterisks). ×12.5, hematoxylin and eosin stain.
Artery, pharynx of a central bearded dragon (Pogona vitticeps). Fibroplasia and degenerate inflammatory cells replace much of the tunica media (black asterisks). Amorphous eosinophilic deposits (white asterisk) are present in the tunica media and intima (fibrinoid necrosis). Microsporidia are present within the lesions (arrow). ×200, hematoxylin and eosin stain. Inset, upper right: Higher magnification of a sporophorous vacuole containing multiple microsporidial spores. ×1,000, hematoxylin and eosin stain. Inset, lower right: These spores stain Gram positive. ×1,000, Gram stain.
Body wall mass, central bearded dragon (Pogona vitticeps). A mass arises within the serosa (arrows) of the body wall and protrudes into the coelom (C). Inflammation is present in the muscular body wall (asterisk). ×12.5, hematoxylin and eosin stain. Inset: The mass is composed of inflammatory cells (mostly lymphocytes, plasma cells, and macrophages) supported by collagen. ×400, hematoxylin and eosin stain.
