PMC5681727_01
Organs removed at necropsy from an Amur tiger (Panthera tigris altaica) with multiple myeloma. (A): Tibia, longitudinal section: multifocal to coalescing haemorrhagic nodules infiltrating the yellow discoloured bone marrow. (B): Liver; multifocal irregularly shaped dark red foci. The capsule over left medial lobe is ruptured, with adherent blood clot. (C): Spleen: diffuse marked splenomegaly. (D): Opened thorax, lung in situ: Multifocal, variably-sized haemorrhages scattered over the pleural surface.
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F1
There were multifocal, oval, dark red nodules in the medullary cavities of the right humerus and right and left tibias (Fig. 1A). There were multifocal, small, irregularly-shaped, flat, dark, hemorrhagic foci affecting all liver lobes (Fig. 1B), continuing into the parenchyma to a depth of 0.5 - 1 cm. There was a linear, 4 cm rupture on the diaphragmatic surface of the left medial liver lobe, with an adherent blood clot (Fig. 1B). The spleen was diffusely enlarged and pink (Fig. 1C), with soft, wet parenchyma. All lung lobes were covered in multifocal-coalescing, variably-sized (0.2 - 1 cm) hemorrhages (Fig 1D).
Photomicrograph of round cell neoplasm in the bone marrow of an Amur tiger (Panthera tigris altaica) with multiple myeloma. (A): Densely-packed, round cells with eosinophilic cytoplasm and eccentric nuclei (malignant plasma cells) (Hematoxylin and eosin; 200X magnification). (B): Neoplastic cells exhibit diffuse, strong brown cytoplasmic labelling for lambda light chains. lambda light chain immunohistochemical staining, hematoxylin counterstain (200X magnification). (C): MUM-1 intranuclear expression in eighty per cent of neoplastic cells. MUM-1 immunohistochemical staining, hematoxylin counterstain (200X magnification). (D): Ninety per cent of neoplastic cells exhibit brown membranous labelling for CD20. CD20 immunohistochemical staining, hematoxylin counterstain (200X magnification).
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F2
All cells infiltrating the bone marrow, liver and spleen were strongly, diffusely positive for lambda light chains (Fig. 2B). Eighty per cent of the neoplastic bone marrow cells exhibited moderate nuclear staining for MUM-1 (Fig. 2C). Ninety per cent of cells infiltrating the bone marrow and the spleen exhibited cytoplasmic CD20 staining (Fig. 2D).