Cellular Pathology. Histopathology Lab #2 (web) Paul Hanna Jan 2018

Transcription

1 Cellular Pathology Histopathology Lab #2 (web) Paul Hanna Jan 2018

2 Slide #91 Clinical History: a necropsy was performed on an aged cat the gross pathological changes included: widespread subcutaneous edema ascites hydrothorax multiple, pale, wedge-shaped lesions in kidneys tissues were sent to AVC for histopathologic examination

3 Well demarcated pale wedge shaped lesion in renal cortex; with base of the wedge near the capsule and apex near cortico-medullary junction.

4 Note size of the infarct depends on caliber of vessel that becomes obstructed

5 Normal kidney, gross sagittal section, cat (above left) and normal histology of the kidney

6 Well demarcated pale wedge shaped lesion in renal cortex; with base of the wedge near the capsule and apex near cortico-medullary junction.

7 Slide #91 Within the affected area the basic architectural arrangement of the glomeruli and tubules is apparent however the cells resemble an eosinophilic shadow (ghost-like remnant) of the original cells. Surrounding layer of inflammatory cells; most of which are degenerate.

8 Within the affected necrotic area the basic architectural arrangement of the glomeruli and tubules is apparent however the cells resemble an eosinophilic shadow (ghost-like remnant) of the original cells. Surrounding layer of inflammatory cells; most of which are degenerate.

9 Within the affected necrotic area the basic architectural arrangement of the glomeruli and tubules is apparent however the cells resemble an eosinophilic shadow (ghost-like remnant) of the original cells. Most nuclei are inapparent (karyolysis) Surrounding layer of inflammatory cells; most of which are degenerate.

10 Within the affected necrotic area the basic architectural arrangement of the glomeruli and tubules is apparent however the cells resemble an eosinophilic shadow (ghost-like remnant) of the original cells. Most nuclei are inapparent (karyolysis)

11 Slide #91 Description: on low-power this section of kidney contains an irregular, wedge-shaped pale eosinophilic area which has a basophilic border. the apex of this triangular area is within the medulla, while the base is approximately 1-2 mm from the capsular surface. the inner material is composed of ghost-like remnants of the renal parenchyma (coagulation necrosis of tubules, glomeruli, etc) and the whole area is surrounded by a thick layer of inflammatory cell debris. there is an increase of fibrous connective tissue and some inflammatory cells within the interstitium of the remainder of the renal cortex (pre-existing nephritis). Morphologic Diagnosis: Renal infarct (locally extensive necrosis of the renal cortex) Comment: an interlobar or arcuate renal artery was obstructed by a thrombus / thromboembolus resulting in ischemia to the renal parenchyma and subsequently coagulation necrosis. layer of inflammatory cells at the margin of the infarct is a response to the dead tissue.

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13 Case #95 History: three-year-old, DLH, female, cat ear margins turning dark color over last few weeks (February)

14 Note, necrotic ear tips (above) and sloughing of necrotic ear tip on cat (right) with some raw (granulation tissue) along the remaining margin.

15 Base of pinna normal tissue Necrotic tip of ear Layer of inflammation separating viable from necrotic tissue

16 Base of pinna normal tissue

17 Base of pinna normal tissue

18 Case #95 Necrotic tip of ear Layer of inflammation separating viable from necrotic tissue

19 Case #95 Necrotic tip of ear Layer of inflammation separating viable from necrotic tissue

20 The affected region appears as an acidophilic shadow (ghost-like remnant) of the normal tissue / cells (ie architecture intact but acidophilia and karyolysis). Note melanin pigment has persisted.

21 The affected region appears as an acidophilic shadow (ghost-like remnant) of the normal tissue / cells (ie architecture intact but acidophilia and karyolysis). Note melanin pigment has persisted.

22 Case #95 Description: on low-power examination a section of pinna shows hypereosinophilia of the peripheral half of the section with a zone of basophilia at the junctional zone. on higher magnification, the affected region appears as an acidophilic shadow (ghost-like remnant) of the normal tissue / cells (ie architecture intact but acidophilia and karyolysis). the basophilic zone, between viable and necrotic tissue, consists of inflammatory cell debris. Morphologic Diagnosis: Locally-extensive necrosis (infarction) of the pinna Comment: lesion is consistent with frostbite (ie dry gangrene = coagulation necrosis of an extremity). the cold temperature caused vasoconstriction (ie reduced blood supply to the ear tip) which resulted in ischemic coagulative necrosis (= infarction) of the ear tip.

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24 Case #60 Clinical History: sudden death in a 1-month-old lamb. at necropsy the lamb was in good body condition, the majority of skeletal muscles & left ventricle wall had numerous irregular patchy areas of white discoloration. a moderate amount of edematous fluid was present within the thoracic and abdominal cavities as well as in ventral dependent areas (ie subcutaneous edema of limbs and ventral abdominal wall).

25 Gross images from a similar case with skeletal muscle lesions (above) and myocardial lesions (right).

26 Skeletal muscle longitudinal sections Skeletal muscle cross sections

27 Three segments of skeletal muscle from affected lamb

28 Case #60

29 Case #60

30 note fragmentation and mineralization of necrotic myocytes Inflammatory cells (mostly macrophages) removing necrotic cells.

31 Fragmented hyalined myofiber Fragmented mineralized myofiber (mineralization is recognized as basophilic granularity and clumps on H&E staining) Inflammatory cells (mostly macrophages) removing necrotic material.

32 Case #60 Description: the skeletal muscle changes vary in the 3 sections of slide #60 in regards to severity. severe lesions are characteristic of coagulation necrosis; ie loss of myofibers with many remaining myofibers showing fragmentation, intensely eosinophilic staining of cytoplasm (hyalinization & loss of striations) and often pyknotic nuclei with aggregates of basophilic, granular material (mineralization). there are frequently many mononuclear cells around myofibers (ie phagocytosis by macrophages). if you examine the slide you will note in some areas there are many clusters of enlarged myofiber nuclei which are indicative of regeneration myofibers. Morphologic Diagnosis: Myopathy, necrotizing, severe with mineralization Comment: the history and lesions are characteristic of nutritional myopathy ( white muscle disease ) due to deficiency of selenium &/or vitamin E.

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34 Case #19 Signalment: one-year-old male sheep. Clinical History: brief history of neurological signs prior to euthanasia. at necropsy, a large abscess was found in the pituitary fossa and a suppurative exudate was present in the meninges of the brainstem. tissues were taken for histopathology including the pituitary gland.

35 Thick dry pus (purulent / suppurative exudate) filling pituitary fossa (sella turcica). Note if the pus was less thick (ie more liquid) pus it would have oozed out of this area and we would not be able to capture it in a histologic section.

36 Acidophilic regions are areas of thick dry pus (liquefactive necrosis) with surrounding basophlic zones of degenerate inflammatory cells (predominately neutrophils). Note if it was less thick (ie more liquid) pus it would have oozed out of the tissue and these spaces would be empty.

37 Acidophilic regions are areas of liquefactive necrosis. On gross exam this would be a thick purulent / suppurative exudate (pus) Surrounding basophlic zones of degenerate inflammatory cells (predominately neutrophils) Areas of viable pituitary gland

38 Acidophilic region of liquefactive necrosis (mostly necrotic neutrophils). Note complete loss of cellular detail (ie amorphous) Surrounding basophlic zone of degenerating neutrophils which eventually liquify to form the bulk of the necrotic material

39 Acidophilic region of liquefactive necrosis (mostly necrotic neutrophils admixed with bacteria). Note complete loss of cellular detail (ie amorphous) Surrounding basophlic zone of degenerating neutrophils which eventually liquify to form the bulk of the necrotic material Fibrous capsule beginning to form in attempt to wall off this inflammatory process

40 Myriads (massive numbers) of bacteria are admixed among the necrotic material. They aren t resolved well in this H&E stain, however a Gram stain of this section would make them more distinctive) Zone of degenerating neutrophils which eventually liquify to form the bulk of the necrotic material (lots of enzymatic digestion)

41 Case #19 Morphologic Features: the majority of normal pituitary tissue is destroyed by the inflammatory reaction. the reaction consists of multifocal to coalescing areas of amorphous eosinophilic material (liquefactive necrosis) which are surrounded by layers of inflammatory cells (mostly degenerate neutrophils) and then bands of fibrous connective tissue. the inflammatory cells are predominately neutrophils with fewer macrophages, lymphocytes and plasma cells. large numbers of bacteria are admixed with the inflammatory cell debris. Morphologic Dx: Pituitary abscess (hypophysitis, suppurative, locally extensive, chronic, severe) Comment: neurologic signs were likely due to accompanying meningitis. Trueperella pyogenes is a frequent cause of abscesses, mastitis & pneumonia in farm animals bacteria reach the pituitary hematogenously (via blood stream) or locally from the oropharynx.

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