Download pdf - SYSTEMIC PATHOLOGY Pathology of Musclepeople.upei.ca/hanna/Muscle-Lab/Muscle-Lab-Web2018.pdf · Cancer cachexia can cases of paraneoplastic cancer cachexia occurs despite adequate

SYSTEMIC PATHOLOGY

Pathology of Muscle

Laboratory

Paul Hanna Winter 2018

Disturbances of Growth and Postmortem Alterations

Muscle Atrophy

• reduction of muscle size and myofiber diameter, due to loss of myofibrils / organelles

• reversible providing the source of injury is removed in relatively short time interval

• histologically, see reduction in myofiber diameters with an unchanged amount of CT

• types of muscle atrophy include:

a) Denervation atrophy

b) Disuse atrophy

c) Atrophy of malnutrition / cachexia / senility

d) Atrophy of endocrine disease

Equine Laryngeal Hemiplegia ("roarers”)

FIG 6-52 & 53 Craniocaudal (left) and dorsal (right) view of the larynx of a horse with a left-side paralysis that resulted in severe denervation

atrophy of all the intrinsic muscles of the larynx except for the cricothyroid. This is especially evident here in the cricoarytenoideus dorsalis

muscle. Veterinary Neuroanatomy and Clinical Neurology, 4th Edition.

Denervation Atrophy

http://arthurveterinaryclinic.blogspot.com

Fig 23-6B (Dyce) Muscles

associated with shoulder and elbow

joints; lateral view.

7, supraspinatus muscle

8, infraspinatus muscle

Equine Suprascapular Neuropathy (“Sweeney”)

Figure 23-43 (Dyce) Distribution of the

nerves in the right forelimb; medial view.

The axillary artery at the shoulder joint is

stippled.

2, suprascapular n.

Denervation Atrophy

Great horned owl, unilateral atrophy of pectoral muscles.

Illustration showing what the pectoral muscles in this bird would

look like in cross-section; note “shrinkage” of the birds right

pectoral muscle indicating atrophy

Denervation Atrophy

Great horned owl, further dissection shows cause of the unilateral

pectoral muscle atrophy; ie tearing / damage (avulsion) of right

brachial plexus (see arrow) resulting in denervation atrophy.

Denervation Atrophy

Great horned owl, atrophic

muscle on left of screen,

normal muscle on right

Denervation Atrophy

Disuse Atrophy

• innervation is intact but there is reduced movement, eg pain, bone fracture,, limb immobilization / cast, etc

• lesions are localized to affected groups of muscles & is mostly type 2 myofibers

Horse with severe muscular atrophy

(white asterisk) of the left leg.

Muscle atrophy was localized to this

limb and was caused by lack of

movement (disuse atrophy) as a

result of a chronic joint injury resulting

in partial ankylosis.

Horse with atrophy of the muscles

of the left upper hindlimb; could be

due to nerve damage or disuse

secondary to a local injury

Atrophy of malnutrition

muscle becomes the source of nutrients

atrophy can start within 24 hours following starvation

type 2 fibers affected more than type 1

Normal pectoral muscle bird (left; with some yellow fat in surface fascia) compared to marked bilateral pectoral muscle atrophy (right; ignore

couple of knife cut artifacts) due to malnutrition / starvation, ie muscle proteins broken down and used for basic energy requirements

Carcass of dog showing severe muscle atrophy due to starvation (owner was

charged by the police). Note the extensive atrophy of scapular muscles (arrow) and

intercostal muscles (asterisks). Intercostal muscles are so atrophic that the lungs

can be seen right through them.

Atrophy of malnutrition

• cow with Johne’s disease which causes diarrhea & weight loss due to protein-losing enteropathy

• other diseases with excessive protein loss (eg intestinal parasitism, protein-losing glomerulopathy) can also cause emaciation

www.nd.gov/ndda/JohnesInAction.jpg www.vetnext.com/fotos/cowjohn1.jpg

Atrophy due to excessive protein loss

Protein losing enteropathy in Johne’s disease is a result of segmental, granulomatous enteritis

Normal

Note expansion of lamina propria with inflammatory cells

Normal control

Normal

control

Note

thickened

ileum from

affected cow

Atrophy due to excessive protein loss

• muscle wasting / weight loss can occur during chronic disease; even with normal energy consumption.

• certain neoplasms and chronic inflammatory diseases; due to cytokines (eg TNF) from tumor cells or Mø’s

Figure 6.23 Cachexia secondary to thoracic neoplasia. Knottenbelt and Pascoe's Color Atlas of Diseases and Disorders of the Horse, 2nd Edition

Fig 5-1 Dog with lymphoma and secondary severe cachexia. Cancer cachexia can

be a common paraneoplastic syndrome (PNS) in dogs and cats. The weight loss noted in

cases of paraneoplastic cancer cachexia occurs despite adequate nutritional intake. The

metabolic alterations associated with cancer cachexia usually occur before clinical signs

of the inciting malignancy appear and unfortunately may continue after the patient is

successfully treated for the tumor. Withrow and MacEwen's Small Animal Clinical Oncology, 5th Edition

Atrophy of cachexia

NUTRITIONAL MYOPATHY (WMD)

Gross Pathology:

• muscle pallor; note, can be subtle in mild cases or inapparent in peracute cases

• in severe cases, muscles are pale with chalky white areas or streaks

Nutritional myopathy, skeletal muscle, bovine. Several areas of pallor within the muscles

WMD lamb. Pallor and white streaking in skeletal muscle of a lamb

with white muscle disease. The extensive calcification of

degenerate/necrotic myofibers that often occurs with WMD accounts

for this pronounced white discoloration (as compared to the more

subtle pallor seen with myodegeneration without calcification)


Bovine (calf) Heart - white muscle disease


Ionophore toxicosis

Case 7-2. Pale discoloration of the skeletal muscle (ie

necrosis). (from AFIP Wednesday Slide Conference - No. 7; October 14, 1998)

Case 7-2. Within the pericardial sac there is 30-50ml of

serosanguinous fluid. The epicadium is pale toward the heart

base and contains dull reddish-pink paintbrush like

hemorrhages apically.

Ionophore toxicosis

Diffuse pallor, (a) Femoral quadriceps muscle in sheep with monensin poisoning and (b) Diffuse myocardium

pallor, more intense in the left ventricle (arrow), sagittal section, heart in sheep with monensin poisoning. Clinical & Pathological Changes in Sheep During a Monensin Toxicity Outbreak in Brazil. AJAVA 2016;11(1): 73-78

Skeletal muscle, degenerative myopathy, subacute, moderate to severe, Quarter Horse, equine. Skeletal muscle. Degenerate / necrotic muscle fibers are

hyalinized, fragmented, and have a loss of cross striations, and are infiltrated and separated by neutrophils, macrophages, serocellular debris.

(from AFIP Wednesday Slide Conference - No. 7 14 October 1998)

Ionophore toxicosis

Masticatory myositis of dogs

Fig 7.7. Masticatory myositis in a German

Shepherd. There is marked swelling of the

masticatory muscles and bilateral exophthalmos,

which is more noticeable in the left eye. (Dr Ingo Walde, FVM, Vienna)

in the acute phase is muscle swelling

Acute eosinophilic myositis. Note, myofiber loss and expansion of endomysium with eosinophils.

Histopathology:

• acutely see edema & extensive infiltration of eosinophils



in the chronic stage there is severe atrophy

Histopathology: chronically see lymphocytes / plasma cells and myofibers become atrophic

Chronic lymphoplasmacytic myositis.

Above - Fig 3-85 (Maxie) Dense infiltrates of lymphocytes, including many plasma cells, separating myofibers in

temporal muscle from a dog with masticatory myositis. This is a particularly florid lesion. H&E stain

Right - In the chronic form,note the extensive loss of myofibers and inflammatory infiltrates; predominantly

lymphocytes and plasma cells (latter marked with arrows). There has been some attempts at repair as shown by

the presence of multinucleated myoblasts (asterisk).


Blackleg

• note, animals often found dead without any clinical signs

• when animals ill, can see lameness, crepitation and swelling

Myonecrosis and hemorrhage in a steer

which died from C. chauvoei infection https://vetpath.wordpress.com

Blackle

Note, emphysema, necrosis and hemorrhage in the

muscle of bovine with blackleg

Blackleg

https://vetpath.wordpress.com


Myocardial necrosis and hemorrhage

Blackleg


Blackleg. muscle showing necrosis, and emphysema

Blackleg. Skeletal muscle with emphysema will float

when placed in water.



Blackleg

Necrosis, loss of nuclei and presence of large bacilli



Blackleg

Gram Positive bacilli in skeletal muscle


Blackleg

Fluorescent Antibody Test (FA test) Note the positive

fluorescence for Clostridium chauvoei. Remember to

submit fresh (non-fixed) tissues for this confirmatory test

• Use FAT or anaerobic culture to confirm Cl. chauvoei

Figure 16.3 Direct fluorescent antibody technique showing C. chauvoei in

muscle tissue from a case of blackleg in a heifer. (×400). Clinical Veterinary Microbiology, 2nd ed.

Blackleg

Clostridial gas gangrene due to C novyi myositis in a Holstein cow.

Local treatment includes surgical incision of skin and fascia to allow

drainage (Courtesy of Dr. Henry Stämpfli)

Malignant oedema is typically seen in rams during late summer/early

autumn when head butting is a common behaviour. The most obvious

clinical sign is marked swelling of the head (“bighead”) particularly

surrounding the eyes which forces the eyelids closed

Malignant edema and gas gangrene

Larval stages of Taenia tapeworms

• cysticercus consists of a single bladder with one scolex

• coenurus consists of a single bladder with many scolices

• strobilocercus is a cysticercus that has begun to elongate / segment while still in the intermediate host

Larval stages of Echinococcus tapeworms

• hydatid cysts are spherical, turgid & fluid-filled; up to 5-10 cm in domestic animals (can be larger in humans)

• Taenia saginata (mostly humans) → Cysticercus bovis mostly in muscle / heart of cattle

Cysticercosis

Cysticercus bovis is the larval stage of Taenia saginata which is the

most common cestode parasite in humans. People become infected

by eating under cooked beef containing these larvae. Cysticerci

commonly found in heart and skeletal muscle (eg tongue, above)

(Cysticercus bovis) within muscle of a beef cow.

• Taenia solium (mostly humans) → C. cellulosae mostly in muscle of domestic or wild pigs

Cysticercosis

(Cysticercus cellulosae) found mainly in the heart and skeletal muscles of domestic or wild pigs

• Taenia ovis (many carnivores) → C. ovis mostly in muscles of sheep and goats

Cysticercosis

C. ovis is the intermediate stage of Taenia ovis. The adult stage

is only found in large canids (dog/wolf) that prey on sheep or

consume offal from the slaughter of sheep

C. ovis in sheep muscle

• Taenia serialis (canids) → Coenurus serialis in subQ & intramuscular tissues of mostly rabbits

→ rarely causes cerebral coenurosis in cats & humans

Coenurosis

Coenurus in fascia/muscle of hind limb of rabbit

Sarcocystosis

• generally too small to be visible grossly and generally no inflammatory reaction to the cysts

Histologic section of muscle from a bovine shows cross-section of

myofiber containing one Sarcocystis cyst filled with hundreds of

bradyzoites.

Note no evidence of an inflammatory response.

Fig 8-32 (Georgis) Sarcocyst of Sarcocystis muris in longitudinal

section of skeletal muscle of a mouse Georgis' Parasitology for Veterinarians, 10th ed.

Sarcocystosis

Sarcocystosis

• exception #1 - there are some large sarcocysts of birds & mammals

Large grossly visible sarcocysts are often seen in waterfowl. They can be few (left) or many (right)

Sarcocytis gigantea in esophagus and diaphragm of a sheep; about the size of a grain of rice

http://www.uobabylon.edu.iq/

Int J Mol Cell Med 2014; 3 (9) 1-6

Sarcocystosis


Sarcocystis aucheniae cysts in llama meat. Note several macroscopic cysts (arrows). Merck Vet Manual - Courtesy of Dr. Gaston Moré.

Sarcocystosis


• exception #2 – occasionally there is an inflammatory reaction to the cysts

• cysts rupture in small % of cattle & swine → focal necrosis & eosinophilic granuloma

• at slaughter see yellow-green foci, a few mm in diameter in skeletal & heart muscle

Note multifocal eosinophilic myositis seen in bovine muscle

at slaughter. Note, microscopically (inset) that the

inflammatory response is centered on a degenerating

sarcocytis cyst within a myofiber.

Sarcocystosis

• exception #2 – occasionally there is an inflammatory reaction to the cysts

• also, small % of cattle at slaughter have locally extensive green discoloration of muscles

• microscopically see severe eosinophilic myositis; (HS reaction to sarcocysts?)

Note locally extensive grey-green discoloration of muscle from beef cow found at

slaugter (no clinical signs); this is characteristic of eosinophilic myositis of cattle Microscopically see expansion of the interstitium and effacement of myofibers

with a massive infiltrate of predominately eosinophils.

Sarcocystosis