case_images: PMC11251540_01
case_images: Gross appearances of the lung, liver and stomach in an 18-month-old male rabbit with pulmonary linguatulosis. A) The lung is slightly swollen and poorly collapsed; there are well-circumscribed, flat or slightly raised, solitary grayish-whitish nodules usually 2.00 - 3.00 mm in diameter (arrows); B) The cross-sectional surface of the lung showing whitish-colored developmental forms of the parasite (arrows); some of which were characteristically tongue-shaped. Emphysematous alveoli as caverns or cystic cavities (circular shape) were also obvious; C) The liver is mildly swollen and there are pale areas with focal disseminated small collapsed foci; D) Multi-focal petechies in the stomach. Note: The cross-sectional surface of the lung was photographed after fixation of the tissue in formalin solution.
case_images: vrf-15-261-g001.jpg
case_images: PMC11251540_01_vrf-15-261-g001.jpg
case_images: F1
case_images: In addition, well-circumscribed, flat or slightly raised, solitary grayish-white nodules, usually 2.00 - 3.00 mm in diameter, were detected (Fig. 1A). Diffuse emphysematous alveoli were also observed as caverns or cystic cavities (Fig. 1B). The liver showed mildly swollen and pale areas with focal disseminated small collapsed foci (Fig. 1C). Mesenterial, portal and bronchial-mediastinal lymph nodes showed hyperemia and edema, and multifocal petechial areas and erosive-ulcerative lesions were found in the stomach (Fig. 1D) and small intestine.
case_images: Histopathological findings in the lung tissue sections of an 18-month-old male rabbit with pulmonary linguatulosis (Hematoxylin and Eosin staining). A) The lung parenchyma showing diffuse thickening of the inter-alveolar septum, alveolar emphysema and numerous nymphs (*) being localized in thin-walled cystic alveolar cavities. The anterior portion of the nymph shows acidophilic glands (square shape); (bar = 500 microm); B) Inter-alveolar septa showing diffusely thickened (diffuse interstitial pneumonia) with marked capillary hyperemia, edema and inflammatory cells infiltration (lymphoid cells, macrophages and eosinophils). Irregularly shaped, hyperchromatic, multi-nucleated cells (megakaryocytes, extra-medullary hematopoietic foci; arrows) can be seen (bar = 50 microm); C) Close-up view of the nymph in Fig. 2A showing multiple transverse grooves and saw-like cuticular spines (arrowheads), peri-buccal hooks (arrows) and acidophilic glands as indicated by * (bar = 250 microm). Thick arrows indicate inflammatory cells (lymphoid cells) infiltration around the nymphs in Fig. 2A and 2C.
case_images: vrf-15-261-g002.jpg
case_images: PMC11251540_01_vrf-15-261-g002.jpg
case_images: F2
case_images: The morphological appearance of the nymphs observed in tissue sections generally showed multiple transverse grooves, saw-like cuticles, peribuccal hooks and acidophilic glands (Figs. 2A and 2C).  The most striking morphological changes in the lung parenchyma were diffuse thickening of the inter-alveolar septum, fibrinoid necrotic vasculitis, medial smooth muscle cells hypertrophy of the arteries, alveolar emphysema and nymphal causative agents (Fig. 2A). The lung parenchyma surrounding these infective larvae (nymphs) was found to be compressive atelectatic, but there were no obvious fibrotic capsule and macrophage proliferations or giant cells; only a cellular reaction consisting of eosinophilic-lymphoid cells and hyperplasic alveolar epithelium were seen (Fig. 2A). Inter-alveolar septa were diffusely thickened (diffuse interstitial pneumonia) with marked capillary hyperemia, edema and inflammatory cells infiltration (lymphoid cells, macrophages and eosinophils; Figs. 2A to 2C). Irregularly shaped, hyper-chromatic, multi-nucleated cells (mega-karyocytes) were observed in the lumen or adherent to the wall of capillaries, arterioles and arteries, being thought to be extra-medullary hematopoietic foci (Fig. 2B).
case_images: Histopathological findings in the lung, liver and kidney tissues sections of an 18-month-old male rabbit with pulmonary linguatulosis (Hematoxylin and Eosin staining). A) The arterial vessel wall showing the marked thickening as a result of smooth muscle cells hypertrophy as indicated by * (bar = 250 microm); B) The vessel showing fibrinoid necrotic vasculitis characterized by eosinophilic-hyalinized fibrin deposits (*), necrosis and inflammatory cells accumulation (arrows; bar = 50 microm); C) The portal areas showing hyperemia and vasculitis (arrows) in portal veins and arteries, proliferation in the bile ducts and hyperplasia in the bile ducts cells (*) and inflammatory cells accumulation (bar = 500 microm); D) The kidneys showing tubular necrosis (*), hyperemia and vasculitis (arrows) and fibrin plugs (double arrows) in the glomerular capillaries (bar = 50.00 microm).
case_images: vrf-15-261-g003.jpg
case_images: PMC11251540_01_vrf-15-261-g003.jpg
case_images: F3
case_images: Tubular necrosis, vasculitis, hyperemia and fibrin plugs were observed in the kidneys, especially in the glomerular capillaries (Fig. 3D). Vasculitis was characterized by the accumulation of eosinophils, erythrocytes and inflammatory cells in the vessel lumen, and the presence of hyalinized-fibrinoid necrotic changes in the vessel walls (Figs. 3A and B). There was also marked thickening of the vessel walls due to the smooth muscle cells hypertrophy in medium and large arteries (Fig. 3A). Eosinophilic-hyalinized fibrin deposits were detected in the lumen of alveoli, capillaries and arterioles (Fig. 3B). In liver, hyperemia and accumulation of inflammatory cells including a small number of eosinophils in sinusoids, venules, portal veins and arteries and portal spaces (Fig. 3C) were detected. Moreover, bile ducts hyperplasia, hemorrhage in the parenchyma, and rarely fibrinoid necrotic changes in the vessel walls were observed (Fig. 3C).