Fig.1.
Slide with multiple tissue sections, dog. Make sure all tissue sections are examined. In this case, only one tissue had pathologic changes. HE.
Fig.2-7.
(
2) Normal lung, dog. Tissue section of lung evidencing the pleura (thick arrow), interlobular septa (thin arrow), two bronchi (asterisks), and multiple bronchioles (arrowheads). HE, obj.2x. (
3) Normal lung, dog. Closer view of the lung shown in
Figure 2 detailing a bronchus lined by ciliated epithelium (arrow) and surrounded by cartilage (asterisk). HE, obj.8x. (
4). Normal lung, dog. Closer view of the lung shown in
Figure 2 highlighting a bronchiole lined by ciliated epithelium (arrow), alveolar septa (circle), alveolar spaces (asterisks), and blood vessels (arrowhead). HE, obj.20x. (
5) Normal kidney, cat. Subgross view of the kidney highlighting the cortex (thick arrow), corticomedullary junction (thin arrow), medulla (arrowhead), and pelvis (asterisk). HE, subgross view. (
6) Normal kidney, cat. Closer view of the renal cortex evidencing multiple glomeruli (arrow), proximal tubules (arrowhead), and distal tubules (asterisk). HE, obj.8x. (
7) Normal kidney, cat. Closer view of the renal medulla and its many collecting ducts (arrow) and the renal pelvis (asterisk). HE, obj.8x.
Fig.8-13.
(
8) Pythiosis, small intestine, dog. The main inflammatory changes expand the intestinal submucosa (arrow) and inner muscular layer (arrowhead). Secondary inflammatory changes are present in the mucosa (white asterisk) and serosa (black asterisk), and should be described after the main lesion. HE, subgross view. (
9) Normal small intestine, dog. Compare the histology of the normal intestine with the affected intestine in
Figure 8. HE, subgross view. (
10) Pythiosis, small intestine, dog. The majority of the inflammatory cells consists of multinucleated giant cells with fewer epithelioid macrophages and fewer lymphocytes and plasma cells. HE, obj.10x. (
11) Fibrovascular tissue, skin, dog. There are numerous fibroblasts (arrow) and newly formed blood vessels (arrowhead) with abundant collagen (asterisk) in an area of chronic inflammation and healing. HE, obj.20x. (
12). Coccidioidomycosis, skin, dog. Fungal spherules (center) are 60μm in diameter and have a 5μm thick, double contoured basophilic wall that surrounds flocculent basophilic material and 8μm in diameter round endospores. HE, obj.60x. (
13) Feline infectious peritonitis, lung, cat. The pleura (arrow) is covered with abundant, eosinophilic lacy material that consists of a web of loosely arranged strands of fibrin admixed with neutrophils (asterisk). HE, obj.8x.
Fig.14.
Parvoviral myocarditis, myocardium, dog. The interstitium (asterisk) is the area more markedly affected, and cardiomyocytes are dissociated due to interstitial accumulations of lymphocytes and plasma cells (arrow). A few cardiomyocytes contain intranuclear viral inclusions (arrowheads). A suitable morphologic diagnosis is “lymphoplasmacytic myocarditis with intranuclear viral inclusions.” Using additional information such as signalment and clinical history, you can make an etiologic diagnosis, establish a cause, and determine a specific condition, which in this case would be “parvoviral myocarditis”, “canine parvovirus-2”, and “canine parvovirosis”, respectively. HE, obj.40x.
Fig.15.
Kidney, cat. Tissue sections depicting the main distribution patterns of lesions: 1) focal lesion (one lesion separated by unaffected tissue); 2) multifocal lesion (multiple lesions distributed throughout the organ separated by unaffected tissue); 3) multifocal to coalescent lesion (multiple lesions that coalesce); 4) focally extensive lesion (lesions extend over approximately one-third of the reference area); 5) segmental lesion (a well-defined segment of the tissue is affected, usually with a distinct geometric shape corresponding to an affected vascular bed); and 6) diffuse lesion (widespread involvement of an organ or tissue). HE, subgross view.
Fig.16-21.
(16) Avian poxvirus infection, skin, canary. Hydropic or ballooning degeneration is characterized by swelling of keratinocytes due to cytoplasmic edema (arrow). Intracytoplasmic viral inclusions (arrowhead) are a hallmark of poxviral infections. HE, obj.20x. (17) Steroid-associated hepatocellular degeneration, liver, dog. Hepatocytes are distended with fine cytoplasmic vacuoles that often give the cells a foamy or lacy appearance typical of glycogen accumulation. HE, obj.20x. (18) Hepatic lipidosis, liver, goat. Hepatocytes are distended with single or multiple cytoplasmic vacuoles that often displace the nuclei to the periphery of the cell. HE, obj.20x. (19) Nuclear changes associated with necrosis (2-4) compared to a normal cell (1). Pyknosis (2) is the condensation of chromatin that makes the nucleus smaller and darker. Karyorrhexis (3) is the fragmentation of nuclear material. Karyolysis (4) is the dissolution of the chromatin by endonucleases leading to nuclear vanishing. (20) Acute hepatotoxicosis, liver, ox. Coagulative necrosis due to acute hepatotoxicosis. A few vacuolated hepatocytes around portal triads (asterisk) appear spared from necrosis. Pyknosis (arrow) and karyorrhexis (arrowhead) are observed throughout. In several hepatocytes, no nucleus is apparent. The eosinophilic hepatocellular cytoplasm is another feature of coagulative necrosis. HE, obj.20x. Image: Service of Veterinary Pathology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. (21) Splenic lymphoid necrosis, spleen, dog. Necrotic lymphocytes exhibit multiple areas of nuclear pyknosis and karyorrhexis throughout. HE, obj.20x.
Fig.22-27
(22) Acute hepatocellular necrosis, liver, dog. Centrilobular hepatocytes have undergone coagulative necrosis and exhibit hypereosinophilic and shrunken cytoplasm with pyknotic or karyorrhectic nuclei. HE, obj.20x. (23) Tuberculosis, lymph node, cow. Mycobacterium bovis typically leads to an extensive central area of caseous necrosis with mineralization (upper left) that is surrounded by multinucleated giant cells, epithelioid macrophages, and fewer lymphocytes and plasma cells (bottom right). HE, obj.20x. Image: Service of Veterinary Pathology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. (24) Abscess, pulmonary artery, goat. The area of liquefactive necrosis (top) consists of abundant cell and nuclear debris admixed with scattered neutrophils. The abscess is surrounded by a layer of inflammatory cells (arrow) and fibrovascular tissue (arrowhead). HE, obj.10x. (25). Fat necrosis secondary to acute pancreatitis, abdominal fat, cat. Fat necrosis occurs due to the action of triacylglycerol-lipase on triacylglycerol, which releases fatty acids and glycerol. Necrotic adipocytes are basophilic due to deposition of mineral. Typically, an inflammatory reaction to the necrotic adipose tissue is present (hence the alternative term steatitis). Regular adipocytes (arrow) and a large cluster of basophilic necrotic adipocytes (arrowhead) are present. Inflammation (asterisk) is also visible. HE, obj.10x. (26) Feline infectious peritonitis, meningeal vein, cat. The vascular wall is expanded and effaced by fibrillar eosinophilic material (fibrin) (arrow) and clusters of inflammatory cells (asterisk). HE, obj.20x. (27) Lupus erythematosus, skin, dog. An isolated apoptotic keratinocyte (center) exhibits hypereosinophilic cytoplasm and nuclear fragmentation. HE, obj.40x.
Fig.28-30.
(
28) Normal skin (abdomen), dog. The epidermis consists of 4-5 layers of keratinocytes covered by thin layers of keratin. HE, obj.10x. (
29) Epidermal hyperplasia (abdomen), skin, dog. Chronic injury has led to marked thickening of the epidermis (epidermal hyperplasia) and orthokeratotic hyperkeratosis. Compare the affected skin with the normal skin in
Figure 28. HE, obj.10x. (
30) Epidermal atrophy (abdomen), skin, dog. Hyperadrenocorticism has caused thinning of the epidermis (atrophy), which consists of two and occasionally three layers of keratinocytes. Compare the lesions with the normal skin in
Figure 28. HE, obj.10x.
Fig.31-36.
(31) Pancreatic nodular hyperplasia, pancreas, cat. These are common lesions in older cats, and consist of well demarcated, nodular areas of hypercellularity composed of normal exocrine cells (arrows). HE, obj.4x. (32) Cardiac hypertrophy, heart, cat. Cardiomyocytes are disorganized and exhibit large, hypertrophied cytoplasm and round nuclei. HE, obj.20x. (33) Skeletal muscle atrophy, cricoarytenoid muscle, horse. Compare the irregularly thinned, atrophied affected myofibers (arrow) with the normal adjacent myofibers (arrowheads). Chronic denervation has led to myofiber atrophy and replacement with fibrous connective tissue. HE, obj.10x. (34) Cerebellar hypoplasia, cerebellum, goat. There is overall hypocellularity across the three cerebellar layers. Compare the affected tissue with the normal cerebellum (right). Leptomeninges (L), molecular layer (M), Purkinje cell layer (P), granular layer (G). HE, obj.20x. (35) Ultraviolet light damage, skin, horse. Keratinocytes are disorganized and form cords and nests throughout (upper left). The superficial dermis (bottom right) is expanded and effaced by densely aggregated, coiled, irregular basophilic elastin fibers (solar elastosis). HE, obj.40x. (36) Necrotizing sialometaplasia, salivary gland, dog. Many salivary ducts have undergone hyperplasia and still have a central lumen (arrow), whereas others have undergone squamous metaplasia (arrowhead) as part of the disease process. HE, obj.20x.
Fig.37-40.
(37) Leptomeningeal melanocytes, brain, cow. Leptomeningeal melanocytes have brown cytoplasmic pigment (arrow). HE, obj.20x. (38). Hemosiderin, spleen, dog. Macrophages throughout the spleen contain distinct, bright to dark brown cytoplasmic pigment (hemosiderin). HE, obj.20x. (39) Bile stasis, liver, sheep. Multiple hepatocytes are disrupted due to canalicular and cytoplasmic accumulation of bile (orange). Necrotic hepatocytes have been replaced by clusters of neutrophils (arrow). HE, obj.20x. (40) Plasmacytic and neutrophilic pododermatitis, skin, cat. Plasma cells contain distinct eosinophilic globules of protein (immunoglobulin) in the cytoplasm (arrows). HE, obj.40x.
Fig.41-44.
(41) Lipofuscinosis, liver, sheep. Hepatocytes contain abundant light brown pigment in the cytoplasm (arrow). HE, obj.40x. (42) Canine distemper, lung, dog. Bronchiolar epithelial cells exhibit intranuclear (arrow) and intracytoplasmic (arrowhead) eosinophilic viral inclusions. HE, obj.40x. (43) Renal tubular necrosis, kidney, sheep. The epithelial tubular cells have undergone coagulative necrosis associated with luminal clusters of red granular hemoglobin pigment (asterisks). HE, obj.10x. (44). Anthracosis, lung, dog. Clusters of macrophages (arrow) with black cytoplasmic pigment (carbon) surround a bronchiole. HE, obj.20x.
Fig.45-47.
(45) Mineralization, skin, dog. Collagen bundles have undergone mineralization, characterized by deposition of granular, basophilic to eosinophilic extracellular material (asterisks). HE, obj.20x. (46). Cholesterol granuloma, fourth ventricle, horse. The granuloma contains numerous acicular (needle-shaped) cholesterol clefts (asterisk) surrounded by inflammatory cells. HE, obj.4x (47). Amyloidosis, kidney, dog. The glomerulus is hypocellular and partially effaced and compressed by eosinophilic, fibrillar, acellular amyloid (asterisk). HE, obj.40x.
Fig.48-49.
(
48) Alveolar edema, lung, dog. Alveolar spaces are filled and expanded with eosinophilic edema fluid (asterisks). Compare it with the normal alveolar spaces in
Figure 4. HE, obj.20x. (
49) Chronic passive congestion, liver, dog. Centrilobular sinusoids (asterisks) are expanded by red blood cells that compress adjacent hepatocytes. Chronic congestion will also cause hypoxia and eventual hepatocellular necrosis (arrow). This is a hallmark of congestive heart failure. HE, obj.10x.
Fig. 50-55
(50) Necrotizing sialometaplasia, salivary gland, dog. A well-demarcated area of coagulative necrosis (infarct) effaces part of the glandular tissue (arrows). The necrotic area is separated from the normal salivary gland tissue (arrowhead) by areas of hemorrhage and inflammation (black asterisk) and fibrosis (white asterisk). HE, obj.2x. (51). Renal infarct, kidney, dog. Diffuse or total renal infarct due to vascular thrombosis and occlusion of the renal artery. (52). Renal infarct, kidney, dog. Focally extensive or subtotal renal infarct due to vascular thrombosis and occlusion of an extra-renal branch of the renal artery. (53). Renal infarct, kidney, dog. Corticomedullary (triangular) renal infarct due to vascular thrombosis and occlusion of an interlobular artery. (54). Renal infarct, kidney, dog. Cortical (trapezoid) renal infarct due to vascular thrombosis and occlusion of an arcuate artery. (55). Renal infarct, kidney, dog. Cortical (wedge-shaped) renal infarct due to vascular thrombosis and occlusion of a radiate artery.
Fig.56-57.
(56) Intestinal volvulus with hemorrhage, intestine, horse. The volvulus has caused impaired blood outflow and widespread congestion and hemorrhage throughout the affected intestinal segment. Such dramatic vascular changes will usually lead to hypoxia and ischemic necrosis of the affected area. HE, obj.2x. Image: Department of Pathology, University of Georgia College of Veterinary Medicine. (57) Vascular thrombosis, salivary gland, dog. A blood vessel is occluded by a solid cluster of eosinophilic fibrin strands (asterisk). The epithelial cells forming adjacent acini have undergone coagulative necrosis due to tissue ischemia caused by vascular compromise. HE, obj.20x.
Fig.58-63.
(58) Suppurative ependymitis, brain, goat. Suppurative inflammation characterized by collections of neutrophils and cell debris admixed with bacteria (arrows) within the lateral ventricle of a goat with septicemia. HE, obj.10x. (59). Lymphoplasmacytic inflammation, skin, dog. Inflammatory cells consist of lymphocytes, plasma cells, and fewer macrophages. HE, obj.40x. (60) Pythiosis, intestine, dog. Granulomatous inflammation is characterized by the presence of epithelioid macrophages and/or multinucleated giant cells, with a variable number of lymphocytes, plasma cells, and, occasionally, neutrophils (pyogranulomatous inflammation). HE, obj.20x. (61) Mycotic dermatitis (pseudomycetoma), skin, cat. Multinucleated giant cells with abundant cytoplasm and multiple nuclei surround clusters of fungal hyphae. HE, obj.20x. (62) Granulomatous myocarditis, heart, cow. Granulomatous inflammation can also occur due to noninfectious causes such as Vicia villosa (hairy vetch) poisoning. HE, obj.40x. (63). Eosinophilic dermatitis, skin, horse. Numerous eosinophils efface the dermis in a horse with allergic dermatitis. HE, obj.40x.
Fig.64-65.
(64) Perianal gland adenoma, skin, dog. A well differentiated benign neoplasm in which neoplastic cells are morphologically similar to the normal cells that form the perianal gland. HE, obj.10x. (65) Histiocytic sarcoma, brain, cat. A poorly differentiated malignant neoplasm in which neoplastic cells display marked pleomorphism, with clear variations in size and shape of the cytoplasm and nucleus. The diagnosis of such poorly differentiated neoplasms often requires immunohistochemistry for confirmation. HE, obj.40x.
Fig.66-67.
(66) Morphologic differences usually observed between benign versus malignant neoplasms. Benign neoplasms (left) tend to be expansile but non-invasive, slow growing, and typically have low mitotic activity. In contrast, malignant neoplasms (right) tend to be expansile and invasive, fast growing, and have a higher mitotic activity. (67) Metastatic spread in malignant neoplasms. Metastasis is an exclusive feature of malignant neoplasms, and refers to the transfer of neoplastic cells from one site (primary neoplasm) to a distant site (metastasis or secondary neoplastic site). In this example, a normal epithelium (1) undergoes malignant transformation (2), with subsequent vascular invasion by neoplastic cells (3). Intravascular neoplastic cells adhere to the endothelial lining at a distant site and invade the adjacent tissues (4), in which they form a secondary (metastatic) neoplasm (5). There is no anatomic connection between the primary and the secondary tumor.
Fig.68.
Metastatic mammary carcinoma, lymph node, dog. Neoplastic epithelial cells (left) originating in the mammary gland tissue infiltrate the subcapsular sinus of a regional lymph node. HE, obj.10x.
Fig.69.
Immunohistochemistry in a nutshell. A primary antibody of known specificity is utilized to detect antigens on the surface of neoplastic cells. Secondary antibodies attach to the primary antibody and enzymatic reactions using chromogens are incorporated and then visualized under the microscope. Chromogen (C), enzyme (E), secondary antibody (SA), primary antibody (PA), tissue antigen (TA), neoplastic cell (NC).
Fig.70.
Cardiac trypanosomiasis, heart, dog. A moderate number of lymphocytes and plasma cells disrupt groups of cardiomyocytes (arrow). An affected myofiber (center) is expanded by a sarcoplasmic protozoal cyst measuring approximately 40μm in diameter and containing 3μm round amastigotes with a central basophilic nucleus and an adjacent rod-shaped kinetoplast (not evident). The morphologic diagnosis in this case would be “Myocardium: Multifocal to coalescing, subacute, moderate lymphoplasmacytic myocarditis with intracytoplasmic protozoan cysts and amastigotes”. The etiologic diagnosis would be “protozoal myocarditis” or “trypanosomal myocarditis”, the etiology would be Trypanosoma cruzi, and the name of the disease would be “canine American trypanosomiasis”. HE, obj.40x.
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