25 - Bones, Joints, and Soft tissues

Question 1

Most common skeletal dysplasia; characterized by disproportionate shortening of the proximal extremities, bowing of the legs, and a lordotic (sway-backed) posture; pathology is mutations on FGFR3; autosomal dominant.

Answer 1

Achondroplasia

Question 2

Most common lethal form of dwarfism; also caused by mutations in FGF3; usual cause of death is respiratory insufficiency (underveloped chest cavity).

Answer 2

Thanatophoric dysplasia

Question 3

This is a group of hereditary disorders caused by defective synthesis of type I collagen; classic finding of a “blue sclerae” is seen in one type of this disorder; has 4 types; Type II is the most lethal; most commonly autosomal dominant.

Answer 3

Osteogenesis imperfect (OI) Brittle bone disease

Question 4

• A disease that manifests with dense but structurally unsound bone due to mutations that result to impaired osteoclast function; also the first disease to be treated with HSC transplantation.
• Eponym for this disease:

Answer 4

• Osteopetrosis (Marble bone disease)
• Albers-Schonberg disease

Question 5

The hallmark of this disease is loss of bone; cortices are thinned and trabeculae are reduced in thickness; osteoclastic activity is present but not dramatically increased; mineral content of the bone tissue is normal.

Answer 5

Osteoporosis

Question 6

Basic difference between osteopenia and osteoporosis.

Answer 6

Severe osteopenia enough to increase risk of fractures in osteoporosis

Question 7

Characterized by repetitive episodes of frenzied, regional osteoclastic activity and bone resorption, followed by exuberant bone formation, and finally by an apparent exhaustion of cellular activity; pathognomonic feature is a “mosaic pattern” of lamellar bone; associated with secondary osteosarcoma.

Answer 7

Paget disease of bone (Osteitis deformans)

Question 8

Condition that results from Vitamin D deficiency; characterized by undermineralization of bone (as opposed to osteoporosis where bone mineral content is normal), rendering one susceptible to fractures.

Answer 8

Rickets (children)/Osteomalacia (adults)

Question 9

Basic difference between rickets and osteomalacia, and osteoporosis.

Answer 9

Osteoporosis: normal mineralization, decreased bone mass; Rickets/Osteomalacia: decreased mineral content of bone

Question 10

Components of von Recklinghausen disease of bone.

Answer 10

• Increased bone cell activity
• peritrabecular fibrosis
• cystic brown tumors

Question 11

Term used for skeletal changes in chronic renal failure (including dialysis).

Answer 11

Renal osteodystrophy

Question 12

Most common route of infection of pyogenic osteomyelitis.

Answer 12

Hematogenous dissemination

Question 13

Most common organism implicated in pyogenic osteomyelitis overall.

Answer 13

S. aureus

Question 14

Common organisms implicated in pyogenic osteomyelitis in IV drug users and patients with GUT infections.

Answer 14

E. coli, Pseudomonas, Klebsiella

Question 15

Common organisms implicated in pyogenic osteomyelitis in neonates.

Answer 15

H. influenzae and GBS (organisms involves in sepsis)

Question 16

Organism implicated in osteomyelitis in patients with sickle cell anemia.

Answer 16

Salmonella

Question 17

A clinically serious form of tuberculous osteomyelitis involving vertebral bodies; can cause vertebral deformity, collapse and posterior displacement leading to neurologic deficits.

Answer 17

Pott disease

Question 18

Bone-forming tumors with marked reactive bone (nidus) formation; clinically, <2 cm lesions; painful but relieved by NSAIDs.

Answer 18

Osteoid osteoma

Question 19

> 2 cm, and pain is not relieved by NSAIDs; morphologically, less nidus formation

Answer 19

Osteoblastomas

Question 20

Basic difference between osteoid osteoma/osteoblastoma and fibrous dysplasia.

Answer 20

Presence of osteoblastic rimming in osteoid osteoma/osteoblastoma

Question 21

A bone-producing malignant mesenchymal tumor, characterized as gritty, gray-white tumors, often exhibiting hemorrhage and cystic degeneration; the production of mineralized or unmineralized bone (osteoid) by malignant cells is essential for diagnosis; associated with Codman triangle and sunburst pattern, radiographically; metaphyseal.

Answer 21

Osteosarcoma

Question 22

Most common benign bone tumor, characterized by hyaline cartilage-capped outgrowths attached by a bony stalk to the underlying skeleton; metaphyseal.

Answer 22

Osteochondroma

Question 23

Second most common malignant matrix-producing tumor of bone; a malignant tumor of chrondrocytes; these lesion arises within the medullary cavity of the bone to form an expansile glistening mass that often erodes the cortex; they exhibit malignant hyaline and myxoid cartilage; in its conventional form, it is almost always never found in children.

Answer 23

Chondrosarcoma

(Note: If you see malignant tumor made of chrondrocytes in a child, think chondroblastic osteosarcoma first)

Question 24

Second most common group of bone sarcomas in children; primary malignant small round-cell tumor of bone and soft tissue, characterized by sheets of small round cells with scant, cleared cytoplasm, circled about a central fibrillary space or “Homer-Wright rosettes”; basically a PNET of bone; associated with a chromosomal translocation abnormality (t(11:22)).

Answer 24

Ewing sarcoma

Question 25

A relatively uncommon benign tumor usually arising in individuals in their 20s to 40s; these are large and red-brown lesions with frequent cystic degeneration, composed of uniform oval mononuclear cells with frequent mitoses, with scattered osteoclast-type giant cells containing 100 or more nuclei; locally invasive; epiphyseal.

Answer 25

Giant cell tumor of bone (Osteoclastoma)

Question 26

Most common skeletal malignancy.

Answer 26

Metastases

Question 27

Most common form of arthritis; most fundamental feature is degeneration of articular cartilage; characterized by fibrillation and cracking of the articular cartilage matrix, bone eburnation, and bony outgrowths/spurs (osteophytes); full-thickness portions of the cartilage are lost, and the subchondral bone plate is exposed.

Answer 27

Osteoarthritis

Question 28

Chronic inflammatory autoimmune disease principally attacking the joints; mechanism of disease is Type IV hypersensitivity; radiographic hallmark of this joint disease are joint effusions and juxta-articular osteopenia with erosion and narrowing of joint space and loss of articular cartilage.

Answer 28

Rheumatoid arthritis (RA)

Question 29

Basic difference between OA and RA.

Answer 29

Joint fusion is absent in OA

Question 30

Classic lesion of RA composed of proliferating synovial lining cells admixed with inflammatory cells, granulation tissue, and fibrous connective tissue; the overgrowth of this tissue is so exuberant that the usually thin, smooth synovial membrane is transformed into lush, edematous, frondlike (villous) projections.

Answer 30

Pannus

Question 31

Examples of seronegative spondyloarthropathies.

Answer 31

Ankylosing spondylitis (Rheumatoid spondylitis, Marie-Strumpell disease), Reactive arthritis (Reiter syndrome), Enteritis-associated arthritis, Psoriatic arthritis

Question 32

Crystal-induced arthropathy due to excessive amounts of uric acid; histologically characterized by a dense neutrophilic infiltrate permeating the synovium and synovial fluid; long, slender, needle-shaped monosodium urate crystals are frequently found in the cytoplasm of the neutrophils as well as in small clusters in the synovium.

Answer 32

Gout

Question 33

Pathognomonic feature of gout; formed by large aggregations of urate crystals surrounded by an intense inflammatory reaction of lymphocytes, macrophages, and foreign-body giant cells, attempting to engulf the masses of crystals.

Answer 33

Tophi

Question 34

Crystal-induced arthropathy due to calcium pyrophosphate deposition; crystals are rhomboid, and positively-birefringent.

Answer 34

Pseudogout

Question 35

Most common soft tissue tumor of adulthood.

Answer 35

Lipoma

Question 36

Most common sarcoma of adulthood.

Answer 36

Liposarcoma

Question 37

Most common soft tissue sarcoma of childhood and adolescence.

Answer 37

Rhabdomyosarcoma

Question 38

Immunostain for rhabdomyoblastic differentiation.

Answer 38

Myogenin

Question 39

Most common neoplasm in women: common site is the uterus.

Answer 39

Leiomyoma

Question 40

Immunostains for smooth muscle differentiation.

Answer 40

Smooth muscle actin, desmin