BONE, JOINT AND SOFT TISSUE LAB ANSWERS

Case 1

1. a. The neoplasm appears to consist of adipose tissue.

b. It arises from primitive mesenchymal cells.

2. a. This tumor is malignant.

b. The presence of lipoblasts and the location in the retroperitoneum indicate a malignant lesion; whereas most lipomas are in superficial subcutaneous tissues and should not have lipoblasts present.

3. Diagnosis is well differentiated liposarcoma--resembles lipoma with interspersed immature lipoblasts.

4. Common locations include deep subcutaneous tissue and retroperitoneum.

5. Age group is typical: 5th-7th decade

6. Liposarcomas are not likely to be cured by resection. Recurrence is common following excision

7. Liposarcomas are rare. Lipomas are very common.

Case 2

1. Rheumatoid arthritis has a diffuse proliferative synovitis with inflammatory infiltrate of macrophages, lymphocyte, plasma cells, and in some instances lymphoid follicles or necrosis and fibrin, called a pannus which covers the articular surface and fills the joint space and eventually may erode the cartilage.

Osteoarthritis begins with a loss of chondrocytes with fissuring then flaking of the articular cartilage until eventually subchondral bone is exposed. Inflammation of synovium is usually mild if it occurs and is secondary to the cartilage changes.

This case is rheumatoid arthritis.

2. Rheumatoid arthritis is a multisystem disease in which joint symptoms are usually prominent. Women are affected more often than men (3:1). Usually small joints of hands and feet are affected and are evident by swelling and redness and pain on arising and after inactivity. Characteristic deformities include radial deviation of wrist with ulnar deviation of the fingers.

Osteoarthritis typically involves weight bearing joints and is usually limited to a few joints and the primary type occurs more often in men and usually has no redness or tenderness.

3. Rheumatoid is thought to be an autoimmune disease-80% have rheumatoid factor-a circulating autoantibody.

Osteoarthritis-2 theories--excessive load on joint causes stresses that derange the cartilage matrix mobilization and synthesis--or the biochemical theory-there is damage to cartilage by collagenases and other lytic enzymes.

4. Rheumatoid factor is an autoantibody (usually IgM directed against the Fc fragment of IgG) found circulating in 80% if patients with rheumatoid arthritis. Yes, this patient is likely to have rheumatoid factor.

5. Juvenile Rheumatoid Arthritis--Still"s disease-acute febrile onset-1/3 have only one or few affected joints--RF infrequent

Felty's Syndrome-splenomegaly, hypersplenism and leg ulcers with polyarticular RA

Ankylosing spondylitis--Marie-Strumpell disease-localized to spine-sacroiliac joints-90-95% have HLA-B27

Case 3

1. The main histologic findings include acute and chronic inflammation surrounding necrotic bone (no nuclei and irregular edges) and new bone formation (lots of nonlamellar or woven or immature bone). New bone produced beneath the periosteum is the involucrum. The necrotic bone embedded in pus is the sequestrum.

2. Osteomyelitis (acute and chronic). The x-ray changes indicate the process has been present for some time. There are lots of plasma cells as well as acute inflammation.

3. In a healing fracture necrotic bone would be present but would not be surrounded by the acute inflammatory exudate. The types of tissues in a healing fracture would depend on the stage of callus: granulation tissue, fibrous tissue, cartilage, and/or new bone.

4. Staphylococcus aureus is the most common organism involved in hematogenous (and iatrogenic) osteomyelitis.

Salmonella may sometimes cause osteomyelitis in sickle cell patients.

Polymicrobial infections are likely to occur in post traumatic osteomyelitis or in elderly patients with peripheral vascular disease.

5. Acute hematogenous osteomyelitis is typically monostotic. (In children it is typically at the ends of the long bones, and in adults it is typically in the vertebral column.)

New borns and sickle cell patients may have polyostotic involvement.

6. Elderly people who are debilitaed or who have peripheral vascular disease are the types of adults that usually get osteomyelitis.

7. X-rays and tomograms are not good at detecting osteomyelitis early.

Radionuclide imaging-radioactive scans permit earlier detection, but does not differentiate bone repair from infection.

In this case there is permeative bone destruction of the humerus with involucrum formation and extensive sequestration indicating the disease had been present for some time.

Case 4

1. The x-ray shows that there is a stalk with continuity of cortex and medullary cavity with the parent bone. Sometimes the stalk will bend away from the joint.

2. Hyaline cartilage overlying lamellar bone. Bone and medullary cavity are in continuity with parent bone.

3. Diagnosis is osteochondroma.

4. Yes the femur is a common location for this bone lesion. The appendicular skeleton is the characteristic location with distal femur being the most common location.

5. Yes, the lesion is benign.

It probably arises as a developmental defect of the epiphyseal plate.

6. Yes, it is one of the most common primary lesions of bone.

Ages commonly affected are 1-3 decades.

7. No treatment unless symptomatic, or growth continues after skeletal maturity or cartilage cap> 2 cm after skeletal maturity.

8. Prognosis is excellent--rare incidence of chondrosarcoma.

Case 5

1. By x-ray exam the lesion is located in short tubular bone of the hand (also common in the feet).

Radiologically a largely radiolucent, lobulated geographic lesion in the metaphysis.

2. Histologically there is lobulated, hypercellular, disorganized hyaline cartilage, without significant atypia. Some lobules are rimmed by thin bone.

3. Chondroma is the diagnosis.

Features of the other lesions in the list:

Osteoid-osteoma: one of most common primary lesions of bone

--radiology--radiolucency surrounded by extreme amount of reactive bone

--micro--interweaving trabecula of osteoid and bone with a capillary background

Chondrosarcoma: core skeleton>appendicular skeleton,

--hypercellular with loss of organization, enlarged nuclei and more than occasional binucleate cell,

Healing fracture

--granulation or fibrous tissue and new bone and cartilage formation

Osteochondroma: appendicular esp femur, tibia and humerous,

--osseous stalk and medulla continuous with parent bone, cartilaginous cap mimic epiphyseal plate

4. Prognosis is good-self limited, slight increase incidence of chondrosarcoma.

5. No treatment is needed unless the lesion is symptomatic when curettage and packing can be performed.

Case 6

1. Histologically the tissues present include a mixture of cartilage, fibrous tissue and new woven bone. Sometimes can be very cellular and clinical and x-ray are very important.

2. Yes, necrotic bone is present centrally.

Loss of nuclei and irregular edges of the bone indicate it is necrotic.

3. The diagnosis is a healing fracture.

4. Cells from the periosteum and from the endosteum proliferate to form the tissues in the callous.

Direct injury and indirect injury from ischemia due to disruption of vessels in the haversian system and periosteum contribute to the bone necrosis.

5. A healing fracture is like tissue repair in other organs in that the early phase is granulation tissue and then fibrous tissue union.

Callous has in addition cartilage and bone formation.

6. The name for the mass of tissue holding the bone ends together is called a callous.

7. This was a complete (complete interruption of the continuity of the bone with separation of it into two fragments).

It was a closed (no disruption of the overlying skin) fracture.

It was traumatic (due to severe stress).

It was not pathologic since there is no evidence that there was a prior disease.

Case 7

1. Microscopically the lesion is a very cellular and pleomorphic neoplasm producing osteoid in a woven or immature pattern.

2. Osteosarcoma is the diagnosis.

It is malignant.

3. Yes, the clinical and x-ray findings are typical.

Can occur in any bone and radiographically is highly variable, destructive lesion with mixed osteoblastic/osteolytic changes.

4. Combination chemotherapy and surgery is the treatment of choice.

5. Long term survival (10yr) is 65-70%.

6. Osteosarcoma occurs in any bone whereas chondrosarcoma occurs most commonly in the core skeleton (limb girdles). Osteosarcoma occurs mostly in 2nd and 3rd decades whereas chondrosarcomas occur in the 4th-7th decades

7. Microscopically in giant cell tumor of bone the mononuclear stromal cells and multinucleated "osteoclast-like giant cells" have nuclear identity, the giant cells are evenly distributed, and mononuclear cells may appear as naked nuclei.