MSS patho lab 2

8/16/2019 MSS patho lab 2

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Cancellous bone under polarized microscope

Here is normal cancellous bone as seen under polarized light

microscopy. The bony lamellae appear as white lines and are arrangedin regular parallel arrays. Cellular marrow is present between thetrabeculae. The bone trabeculae form a complex three-dimensionalstructure that provides strength without the weight of solid bone. Thebony spicules are of even dimension, with occasional lacunae containingosteocytes.

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Paget disease under low-power microscope

This is Paget disease of bone in which the mixed osteoclastic andosteoblastic stage is present. A line of osteoblasts is present forming

new bone, but lacunae containing multinucleate osteoclasts are at thesame time destroying bone. The result is a patchwork mosaic of bonewithout an evenly formed lamellar structure. This stage of Paget diseaseis preceded by a mainly lytic phase and is followed by a "burnt out"sclerotic phase.

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Paget disease under polarized microscope

Paget disease of bone is typically seen in elderly Caucasians ofEuropean ancestry. The serum alkaline phosphatase is increased, butthe serum calcium and parathormone are not. Under polarized light, theirregularities of the bony lamellae are apparent, with a "tile-like" or

"mosaic" pattern.


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Osteoporosis of vertebrae

The bone in these vertebral bodies demonstrates marked osteoporosiswith thinning and loss of bony trabeculae. The second body from the

right shows a greater degree of compression than the others.Osteoporosis is accelerated bone loss with age and is particularlycommon amongst postmenopausal women, putting them at risk forfractures (hip, wrist, vertebrae).


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Compressed fracture of vertebrae

Here is a "compressed" fracture of the vertebral column. Themiddle vertebral body shown here is greatly reduced in size.Such fractures are common in persons with osteoporosis inwhich there is accelerated bone loss, particularly older

women, and can occur with even minor trauma.

The area surrounded by the orange line , represents

the region of compressed fracture.


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Osteoarthritis in femoral head

The femoral head at the left (removed because of fracture)shows smooth, glistening articular cartilage, while the femoralhead at the right shows a rough, eburnated, irregularappearance typical for osteoarthritis.


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Rheumatoid arthritis

The prominent ulnar deviation of the hands and "swan neck"

deformity of the fingers seen here is due to rheumatoid

arthritis (RA). This autoimmune disease leads to synovialproliferation with inflammation and joint destruction, typically

in a symmetrical pattern involving small joints of hands and

feet, followed by wrists, ankles, elbows, and knees.

Rheumatoid factor can be identified serologically in most, but

not all, RA patients.


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Rheumatoid arthritis / rheumatoid nodule

Sometimes persons with rheumatoid arthritis (RA) have

rheumatoid nodules form in subcutaneous locations at

pressure points, such as the elbow shown here. Rheumatoid

nodules may also appear viscerally, such as on the pleura of

the lung.


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Rheumatoid arthritis / pannus

This is the synovium in rheumatoid arthritis. There is chronic

inflammation with lymphocytes and plasma cells that produce

the blue areas beneath the nodular proliferations. This

"pannus" is destructive and produces erosion of the articularcartilage, eventually destroying the joint.


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Rheumatoid arthritis / rheumatoid nodule

Here is a rheumatoid nodule. Such nodules are seen in

patients with severe rheumatoid arthritis and appear beneath

the skin over bony prominences such as the elbow. They can

occasionally appear in visceral organs. There is a central area

of fibrinoid necrosis surrounded by pallisading epithelioidmacrophages. and other mononuclear cells.


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Gouty tophus in soft tissues

The pale areas seen here are tophi, or aggregates of urate

crystals surrounded by infiltrates of lymphocytes,

macrophages, and foreign body giant cells. A tophus is the

characteristic finding of gout. Tophi are most likely to be foundin soft tissues, including tendons and ligaments, around joints.

Less commonly tophi appear elsewhere. Tophaceous gout

results from continued precipitation of sodium urate crystals

during attacks of acute gout.


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Joint fluid in Gouty arthritis

If synovial fluid is aspirated from a patient with gout, the fluid

can be examined for the presence of sodium urate crystals,

which are seen here to be needle shaped. If they are

observed under polarized light with a red compensator, they

appear yellow (negatively birefringent) in the main ("slow")

axis of the compensator and blue in the opposite

perpendicular direction.


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Chondracalcinosis with CPPD

A rhromboid shaped crystal of calcium pyrophosphate dihydrate(CPPD) appears bluish-white (weak positive birefringence) bypolarized light microscopy with a red plate. Calcium

pyrophosphate crystal deposition disease (sometimes called"pseudogout") is most often seen in persons over the age of 50,and can lead to acute, subacute, or chronic arthritis of knees,wrists, elbows, shoulders, and ankles. The articular damage isprogressive, though in most persons the disease is not severe.


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Normal skeletal muscle

At medium power in cross section with ATPase stain at pH 9.4,

the pattern of type 1 and type 2 fibers is seen. These fibers are

normally intermixed to form a checkerboard pattern. The type 1

fibers (slow twitch, oxidative) are light tan and the type 2

fibers (mainly glycolytic) stain dark brown.

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Normal skeletal muscle

This is a normal NADH stain (which localizes oxidative enzymes)

of skeletal muscle also demonstrating a mixture of type 1 andtype 2 muscle fibers. The type 1 fibers stain darkly and the type

2 fibers stain lighter.


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reinervation of muscle with type grouping

This NADH stain shows the findings with reinervation of muscle

with type grouping. One nerve tends to reinervate an entiregroup of muscle fibers and organizes them to be of a single type.

Thus, most of the fibers here are type 1.


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Duchenne muscular dystrophy

This is Duchenne muscular dystrophy. There is degeneration of

muscle fibers along with some regeneration and scattered

chronic inflammatory cells, fibrosis, and hypertrophy of remaining

muscle fibers. Duchenne's is due to a defective gene on the X

chromosome that leads to an inability to produce the membrane

skeletal protein dystrophin. Thus, this is an X-linked recessive

disorder. About 30% of cases represent new mutations.


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Note the adipose tissue and the increased fibrous connective

tissue revealed by this trichrome stain. There are larger overlycontracted muscle fibers with scattered small degenerating or

regenerating fibers. Patients with Duchenne muscular dystrophy

initially develop more proximal muscle weakness early in

childhood, but they are typically wheelchair-bound by age 10 and

die of respiratory failure by the second or third decade.


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Normal muscle with immunoperoxidase stain

This immunoperoxidase stain utilizes antibody to the muscle

protein called dystrophin, which is seen to be localized at theperiphery of the normal muscle fibers shown here. Dystrophin,

which is coded by a gene on the X chromosome, appears to

stabilize the membrane.


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This immunoperoxidase stain utilizes antibody to the muscle

protein called dystrophin, which is seen to be localized at the

periphery of the normal muscle fibers shown here. Dystrophin,

which is coded by a gene on the X chromosome, appears to

stabilize the membrane. Note here the absence of the stain

because it needs dystrophin to be stabilized and dystrophin is

absent .


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Polymyositis under microscope

This is polymyositis. Note the marked inflammatory cell infiltrate.

This is an autoimmune disease that can be associated with

polymyositis or dermatomyositis. Polymyositis results from the

cytotoxic effects of CD8+ lymphocytes recognizing HLA class 1

MHC molecules on sarcolemmal membranes. Dermatomyositis

is mainly mediated via a vasculitis affecting small capillaries, and

has a skin rash (typically the violaceous "heliotrope" rash of

eyelids).


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Polymyositis under microscope

Here is another example of polymyositis. Note the degeneration

of muscle fibers in the region of inflammation. Of the

autoantibodies, anti-Jo1 is probably the most common with this

disorder.


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Desmoids

This is another low grade lesion of soft tissue known as a

desmoid tumor. These are aggressive fibroblastic proliferations

that can occur in shoulder, chest wall, neck, and thigh in both

men and women. In women during or just following pregancy,

they may appear in abdominal wall.


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Desmoids

Desmoid tumors are poorly demarcated and invade surrounding

soft tissues, so they must be excised with a wide margin.

Microscopically, they are composed of fibroblastic cells in acollagenous stroma. There can be some pleomorphism and a

rare mitotic figure.


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Lipoma

This is a lipoma. It is benign and tends to enlarge very slowly

over time. Note how it is indistinguishable microscopically from

normal adipose tissue. It is a neoplasm because grossly it

formed a mass lesion.


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Liposarcoma

This is a liposarcoma arising in the region of the lower thighposterior to the knee. Note that it is a large, bulky mass.

There is enough differentiation to provide a yellowish hue(suggesting adipose tissue differentiation) to this fleshy tumormass. [Image courtesy of John Nicholls MD, Hong KongUniversity]


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Liposarcoma

Here is a low grade liposarcoma. There are still recognizablecells with lipid, resembling steatocytes, but there is more

stroma and some cells have larger nuclei. Of course, grosslythis would tend to be a larger mass than a benign lipoma.


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Liposarcoma

This is the microscopic appearance of a higher grade

liposarcoma of the thigh. Retroperitoneum is another likely

primary site for liposarcoma. There is enough differentiation

with vacuolated, lipid filled cells, to determine the cell of origin.


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Liposarcoma

At high magnification, the lipoblasts in this liposarcoma are

visible.


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MSS patho lab 2

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