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syspath
12/05
hendrick

*note* FIP is fair game for the final exam.

today will be a slideshow. everything gone over today is fair game for 
the exam.
some of this will be new lesions and changes; some will be review. we'll 
see some common postmortem changes that we see in animals that shouldn't 
be confused with real lesions. 

slides:

starting with skin, here is a cutaneous tag. these are pedunculated, 
warty or verucous lesions hanging off the skin of aged dogs or rarely 
cats. usually pieces of redundant skin - normal histo, just extra. often 
get secondary ulceration/inflammation due to their protruding from 
surface. can be white, red, or black. realize these are benign. people 
will remove them from aged dogs with a tentative dx of papilloma - that 
isn't really something seen in old dogs. papillomas are viral induced, 
seen in young animals, usually at mucocutaneous junctions. these are not 
the same as skin tags. 

histiocytoma - most common benign skin tumor of young dogs. smooth, 
round, central red umbilication - "button tumor" seen usually on heads or 
anterior body of young dogs, but can occur anywhere on skin of any age of 
dog. these are of langerhans cell origin. it is probably a benign 
proliferation of langerhans cells rather than actual neoplasms. they go 
away on their own.

cross section of any of the hair follicular tumors - have characteristic 
appearance of being filled with granular almost caseous material, often 
with hair in the middle. benign tumors. well encapsulated. seen commonly 
in dogs, less in cats, excision is curative.

squamous cell carcinoma in white cat on ear. very destructive lesion, 
tends to occur on tips of ears, nose, eyelids, of white cats. associated 
with UV radiation. best prevention is keeping these cats inside. very 
infiltrative tumors. all you can do is amputate as much of the ear as you 
can. luckily complete excision is often curative - but you can't always 
accomplish complete excision. SCC often preceded by dysplastic changes in 
the skin.

finely encapsulated, trabeculated lesion seen in skin and tongue of large 
breed dogs. grossly chalky, granular, toothpaste consistency. material is 
white. this one is in the skin between the epidermis and dermis. 
histologically this is mineralized debris with mphages and giant cells - 
calcinosis circumscripta. different from calcinosis cutis seen with 
cushing's dz - that's a plaquelike zone of mineralization affecting 
collagen. calcinosis circumscripta are benign, but can be problematic if 
near joints. if you break this down and release material into dermis it 
will cause more inflammatory granulomatous reaction. young rottie or GSD 
prone to this.

well circumscribed mass in dermis - red and white - lacy trabeculae 
containing red material which is blood. this is a hemangioma. pretty 
common. more common in dogs. sometimes b/c the blood looks brown 
sometimes the tumor is confused with dermal melanoma. histologically this 
is easy to differentiate. in general,most melanomas start higher up 
anyway, not down in the lower dermis like the hemangioma does. these are 
easy to remove and excision is usually curative - although some of them 
may also be associated with UV light, and some of them will occur more 
often in dogs with thin, white haircoats. a few of these will transform 
into hemangiosarcoma. so it is a good idea to remove these. 

lipoma - classic example - teardrop tan smooth mass. common in dogs, rare 
in cats. benign tumors that usually are removed because they're large. 
tumor of adipose tissue.

slice of vertebral column - irregular growths of bone along ventral 
surface of vertebrae bridging intervertebral spaces. very very common in 
old dogs. "bridging spondylosis" - very commonly seen as an incidental 
finding. no clinical significance. can bridge til the cows come home with 
no sign of damage or clinical problems. 

humerus - areas on articular surfaces where cartilage has been lost - 
flaps on one, erosion on the other. degenerative joint disease - commonly 
seen in older dogs. looks the same as osteochondrosis dissecans in young 
dog, but in older animal more of a reaction to instability and wt bearing 
causes cartilage loss, eburnation, osteophyte proliferation around the 
edge. about 50% of dogs in post room have some degree of DJD. degree 
doesn't correlate well with clinical signs. animal's personality has a 
lot to do with it. 

bird head - hemorrhage over the skull - this is an agonal change in birds 
that die. they have a lot of sinuses in their skulls and will look 
ecchymotic like this. probably this isn't a clinically significant 
finding without associated fractures or other signs of trauma. 

trachea with a widened ligament which causes it to be dorsoventrally 
flattened. this is seen in many small chondrodystrophic dogs with 
overlong soft palates, lots of upper respiratory problems. this is part 
of their problem. this is a collapsing trachea (well, this causes it). 
but some dogs will have this that aren't one of the expected breeds, and 
not all dogs with this have clinical signs. so. kind of tricky.

trachea with foam in it. when you do a postmortem exam you often find a 
little bit of foam in the trachea as a result of the agony of death. but 
if you see foam filling the trachea, it's usually reflecting pulmonary 
edema. 

normal salmon colored, spongy, normal lungs.

red/pink striped lungs. rib impressions apparent. tips of lobes very pale 
pink/white. 

there are often postmortem changes in lungs making it very hard to figure 
out what happened antemortem. pooling of blood and fluid will make lungs 
feel firm, consolidated even if they were normal.

especially in cats, we often see the apex of cranial lobes being foamy 
and aerated with emphysematous appearance. apical emphysema is common 
postmortem change in cats. the rib impressions could be there because of 
ascites - something in abdomen pushing diaphragm forward, pushing lungs 
into ribs.

another change - another cat, but this could be a ferret which also gets 
this lesion - just beneath the pleura are these white areas of 
collections of macrophages - subpleural mphage foci. commonly seen pm 
changes. seen only really in cats and ferrets. round, irregular, flat, 
white, tan foci just beneath pleural surface. foamy mphages containing 
debris,granular material. accentuated when lungs are edematous. 

in many aged dogs you will see and feel tiny pinpoint hard foci in the 
lungs - and see it on radiographs - ectopic bone - seen quite a lot. 

uremic mineralization - lines of mineral deposition between the ribs 
inside the chest wall. plaques / perpendicular arrays of mineral. not all 
uremic animals have this, but really nothing but uremia causes this. 
would be gritty when  you cut it.

dr hendrick's favorite lesion - carcinomatosis - raised nodules and 
plaques, coalescing, tan/yellow/ and very firm but not hard. this is 
inside chest wall. where is primary? mammary, prostate, lung, anywhere.

sqq of skin and other organs doesn't tend to produce carcinomatosis.

another bird - heart, trachea, lung. this is here to show us the gross, 
brown yellow discoloratioon, involving most of lung and covering some 
area of heart - hard to figure out at first, but then you find out what 
was going on - was euthanized with huge amt of euthanasia solu'n - which 
colors organs these horrible colors, brown/green, so it looks necrotic. 

dog heart here exhibits area of brown discoloration - also due to 
euthanasia solution. this can be disconcerting esp if lesion is know to 
involve the heart. if you suspect heart problem try to use less 
euthanasia solu'n or at least don't inject it into the heart - will cause 
wierd histological artifacts if you inect into the heart. things will 
look shiny.

also the solution can preceipitate out into yellow, granular material and 
be seen on endocardium. 

plaque of grey material covering epicardium on right atrial appendage and 
part of epicardium of upper right ventricle in spots - mild/moderate 
epicarditis - fibrosys with lymphs, plasma cells, etc. may be anatomical 
reason to cause epicarditis here. this is a common, clinically 
insignificant lesion in older dogs. 

slide - diffuse, white tan nodularity of AV valves which seem sort of 
contracted. smooth. L ventricular dilation. valves probably 
incompetent.chronic over volume. also there is a jet lesion - grey plaque 
of fibrosis where blood pulses through incompetent valve and hits far 
wall.  this was endocardiosis.

vegetative endocarditis
irregular, reddened, verucous growth on valves. not endocardiosis but 
vegetative endocarditis. what's the most common sequela? emboli to 
kidneys, septic embolism and death. 

not infrequent in dogs, rare in cats - chicken fat clot. sometimes you 
find vessels filled with firm, rubbery, chicken skin looking clot. not a 
thrombus. will pop right out. not a problem, just the way blood clots 
sometimes.

different cardiomyopathies in cats - probably most important cardiac dz 
in cats. abnormal one is about 2.5 times normal size, it's lighter 
tan/pink instead of dark red/mahogany (although the color discrepancy is 
weird. 
as said often in gross demo - one way from looking at a catheart and 
saying something is wrong is when the Left auricle is enlarged. usually 
right is bigger than left in cat. if left is bigger it suggests something 
wrong with ventricle, and blood backing up in left auricle. other ddx for 
big heart in cat? hyperthyroidism. but this cat had hypertrophic 
cardiomyopathy. left heart very very very thick with little lumen. right 
is thick also.

another cat with a big heart - this cat had dilated cardiomyopathy - the 
cause of this - you know, it used to be very common because its related 
to taurine deficiency, but now we don't see it anymore b/c cat food is 
supplemented.

third form of cardiomyopathy - look at aortic outflow tract. and the 
ventricle below the aortic outflow tract. seen in young cats. 
endomyocarditis cardiomyopathy. area right below aortic valve, in 
edocardium, looks hyperemic, discolored, with inflammatory infiltrate 
which can vary but seems to involve endocardium and extend a bit into the 
myocardium.etiology unknown. this is not incidental - this is 
pathological and can kill the cat. heart not as big as hypertrophic 
cardiomyopathy but still a large heart. 

one other kind of cardiomyopathy - restrictive form. there is grey/white 
fibrous CT growing within heart, restricting contractile ability. this 
lesion occurs where the endomyocarditis form occurs - maybe this is 
scarring post inflammatory process. this is seen in older animals.

sequelae - backup of blood into left atrium - dilating it. spaces of 
blood in atrium - thrombus formation - all forms of cardiomyopathy can 
lead to saddle embolus at aortic bifurcation extending into iliac 
arteries. some cats will have these without clinical signs but you should 
check for it!

note also that these animals with cardiomyopathy (any form) will often 
show no clinical signs, but then will go to the vet for a procedure, and 
then will drop dead suddenly within a day or two.

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more slides:

oral mass - ddx epulis or gingival hyperplasia - diffuse, multinodular 
growth with pigmented and nonpigmented areas. seen mostly in aged dogs.

underside of tongue - uremic mineralization and ulcers - dark red/brown 
areas.

open esophagus from a dog with little tiny pinprick grey raised things - 
common age related change in the dog. tiny, punctate cysts on mucosa of 
caudal esophagus. they are dilated ducts of the submucosal glands of the 
esophagus. may contain inspissated secretions. benign. common. age 
related.

parvovirus intestinal lesions...

intussusception - recall agonal intussusception can occur as well. guts 
get hypermotile with death. smooth, normal color, easily reducible.

premortem intussusception - shows signs of obstructed bowel, red, black, 
necrotic segment, etc. 

meckle's diverticulum - usually benign, rarely can be nidus for 
inflammation or neoplasia.

pacinian corpuscles - do not remove them! they're normal :)

another thing people see in surgery commonly - this one is on a little 
stalk - in the mesenteric fat you may see well circumscribed, smooth, 
brown-gold, honey looking mass. very characteristic color. they are areas 
of fat necrosis. very regional. necrotic fat replaced by debris and 
hemorrhage and it's all encapsulated with fibrosis. why they occur we're 
not sure. trauma? devascularization? but they are rounded and smooth and 
look obvious. 
usually seen in dogs.

9 month old cat - FIP - wet form. full of fibrinous, sticky, tenacious, 
gooey amber fluid. some will get a bit more solid and lay out on the 
organs and form some sheets of fibrin. ddx- other inflammation or 
effusion. but this is main dx in young animal.

liver - normal variation on edge of liver - scalloped edge/serrated 
appearance. common, insignificant.

liver with a little section showing tension lipidosis at area of fascial 
attachement - the hepatocytes in that area accumulate fat. this is 
totally unimportant but you should recognize it.

fatty liver - severe diffuse fatty change - three causes -> anorexia, 
diabetes mellitus, toxins, (also pregnancy but not in small domestic 
animals, only in large animals). 

it's important clinically and surgically to recognize nodular hyperplasia 
in the liver. do not assume a liver mass is neoplastic. if there is tumor 
in spleen and nodular hyperplasia in liver....don't kill dog! many old 
dogs have nodular hyperplasia in liver. on cut surface usually generally 
similar to normal parenchyma of liver. sometimes not - can be dark or 
pale - fatty, or glycogen rich. can be quite large nodules.

hepatoma - can mimic nodular hyperplasia. hepatomas tend to have 
capsules. histologically they show loss of architecture, while nodular 
hyperplasia retains normal architecture. this is also benign.

a reminder of steroid hepatopathy - slightly enlarged liver with some 
mottling of parenchyma, usually a bit more orange/tan. histologically - 
midzonal hepatocellular swelling and clearing. very characteristic and 
common lesion. 

example of liver with multifocal hepatic necrosis. whole liver is mottled 
red and yellow. areas that can be pinpoint to coalescing of different 
color than normal liver - lighter or darker depending on what's happening 
- if it's hemorrhaging into necrotic areas, will be darker. here we have 
a fatty liver with red areas of necrosis - yellow and red all over. yuck.


another liver from a cat - telangiectasia - dilation of the sinusoids. 
irregular. clinically insignificant. some red patches are seen diffusely 
over liver.

cross section of nutmeg liver - chronic passive congestion. mottled 
red/pale pink.

bulbous liver mass - cystic mass on edge of liver lobe of cat - this is 
the appearance of the biliary cystadenoma. important to think of during 
surgery. a number of aged cats will get these - cystic, with amber fluid 
within. usually quite peripheral. sometimes will occur a bit near the 
bile duct or hilar system and hard to remove. should remove even though 
benign b/c can get really big and compress other organs and cause 
vomiting, etc. also if you palpate it you'll wonder what it is. gross 
appearance is classic for biliary cystadenoma - benign. carcinoma very 
rare.

bilobed gall bladder - congenital abnormality of no significance seen in 
cat.

open gall bladder - small brown spots  - cystic mucosal hyperplasia - 
another one of those things we see commonly in aged dogs. no clinical 
significance. 

nodular thing in older animals that isn't neoplasia - nodular hyperplasia 
of pancreas - white/pink nodules all over pancreas. this is really not 
going to be anything else. LSA could infiltrate and do this but it is 
very rare in pancreas. pancreatic neoplasia tends to be focal. this is 
diffuse.

spleen - wrinkled with siderofibrotic plaques on edges - fibrous CT 
intermingled with some macrophages and blood pigments, which is why it is 
green/brown/orange. common age related change, unknown etiology. no 
significance.

spleen with well demarcated grey green black foci on perimeter - 
infarcts, common in dogs, not clear why they get them, mostly they aren't 
clinically significant. if very large can become hemorrhagic and can 
mimic hemangiosarcoma.

large nodule: nodular hyperplasia, hemangiosarcoma, or hematoma? this is 
nodular hyperplasia but could be any of those. two other examples are 
shown - can be quite large and ugly. should always biopsy these 
(generally via splenectomy). send in many pieces from the edges of the 
mass. the middle will often be necrotic.

here is one that is hemangiosarcoma. most affected - german sheperd and 
golden retriever. rare in cats. looks similar to nodular hyperplasia.

bulging LN w/loss of architecture - LSA. 

lung of cat with subpleural macrophage foci and there is a huge cranial 
mediastinal mass that's soft, bulging, tan, and pink - LSA. thymoma would 
be a ddx in aged dog or goat but is very rare in cats. in cats, 
lymphosarcoma more common. 

kidney from cat - yellow - normal color. what's wrong with it? radiating 
streaks of fibrosis corresponding to divots in cortex. hydronephrosis. 
why? can occur either from obstruction below or because the fibrosis in 
kidney is pulling it up - due to decrease in tissue in the kidney and 
contraction up towards cortex. so the whole thing is called chronic 
pyelonephritis. there is also blood under the capsule - probably because 
someone palpated the kidney too hard, and caused subcapsular hemorrhage. 


polar infarcts - loss of parenchyma and some wedges of grey tissue at 
ends of kidneys. commonly seen in cats. 

white/tan bulging masses on kidney - LSA. ddx FIP. these cat kidneys 
appear more like LSA - smooth and bulgy - but could be FIP.

another cat kidney - this is FIP. white/red nodules, smaller and less 
bulging - but again - these can look VERY SIMILAR. if you have white 
nodules in the kidney it could be either. think about it - if masses tend 
to go along paths of blood vessels, that is a hint that it might be FIP. 
also think about history and rest of the body. you could confirm via 
histopathology.

big prostate. cystic hyperplasia. benign cystic hyperplasia, but since 
there is no malignant counterpart you don't have to say it's benign. can 
lead to pain, dysuria.

testicle - classic appearance of leydig/interstitial cell tumor. very 
well circumscribed, encapsulated, yellow-tan, hemorrhagic. yellow-tan 
because cells are lipid rich. 

another pair of testicles - tan, soft, bulging seminoma. made of sheets 
of round cells which if you think of lymphosarcoma, should look similar - 
both made of round cells. 

another testicle - parenchyma replaced with white/grey mass with 
trabeculae through it - contralateral testicle is really small. this is a 
sertoli cell tumor. firm, grey, spherous, sclerotic, trabeculated. 
secretes estrogen. 

most testicular tumors are benign and cured by excision.

females:

ovarian cysts. multiple cysts on both ovaries.

cystic endometrial hyperplasia - proliferative hyperplasia of endometrial 
glands - predisposed to develop pyometra.

parathyroid glands - in a cat, most common cause of bilateral parathyroid 
hyperplasia is chronic renal failure. in dog, most common cause is 
chronic renal failure. in horse, nutritional. in monkey, nutritional 
(cage paralysis). in iguana, also nutritional.

back of skull of dog - common anomaly of no significance but sometimes 
seen - keyhole foramen magnum - loss of normal bone - no clinical 
problems from this. 

brain - old dog - white stuff in the sulci - as dogs age we see meningeal 
fibrosis - grey, membranous appearance to meninges especially prominent 
in the sulci. totally insignificant common age related change.

one of most common postmortem lesions, seen all the time - due to poor 
fixation by people sending them in - this segment of liver is only 
partially fixed, and the whole rest of it is not fixed, it is autolysed. 
so autolysis will occur if it isn't properly fixed. should use 10 parts 
formalin to 1 part tissue. if tissue is big, get a bigger jar. do not 
shove a whole heart into a tiny container!

with electrocautery which is often used in surgery - please do not use it 
on tissue intended for biopsy. cauterize the part you leave in after you 
cut out the part you're submitting.




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