Musculoskeletal System

Question 1

Uniformly fatal variant of osteogenesis imperfecta

Answer 1

Type II OI

Question 2

The underlying etiology in achondroplasia is a point mutation in the ___ that results in its constitutive activation and inhibits chondrocyte proliferation.

Answer 2

Fibroblast growth factor 3

Question 3

A variant of osteopetrosis is characterized by deficiency in ____ necessary for osteoclast hydrogen ion secretion and bone acidification.

Answer 3

Carbonic anhydrase II

Question 4

Complications of osteopetrosis

Answer 4

Fractures
Cranial nerve deficits (from compression of surrounding bone)
Recurrent infections
Hepatosplenomegaly (extramedullary hematopoiesis)

Question 5

Which is more effective in increasing bone mass?
A. Resistance exercises (weight training)
B. Endurance activities (jogging)

Answer 5

A. The magnitude of skeletal loading is more important than the number of load cycles.

Question 6

What are two factors that conspire to convert macrophages into osteoclasts?

Answer 6

RANK (RANK-R in macrophages; RANK expressed by stromal cells)
M-CSF (secreted by osteoblasts)

Question 7

Pathognomonic histologic feature of Paget disease

Answer 7

Mosaic pattern of lamellar bone

Question 8

Paget disease is associated with ___ infection.

Answer 8

Paramyxovirus

Question 9

Cytokines produced in large amounts in pagetic bone.

Answer 9

IL-1

M-CSF

Question 10

Collections of osteoclasts, reactive giant cells, and hemorrhagic debris form a distinct mass termed ___.

Answer 10

Brown tumor of hyperparathyroidism

Question 11

Osteonecrosis Quiz
A. Subchondral infarct
B. Medullary infarct

1. Pain during physical activity
2. Stable

Answer 11

1. A

2. B

Question 12

Favored bony sites of hematogenous spread of TB.

Answer 12

Long bones

Vertebrae

Question 13

Tumors of Bone Quiz

Cortical tumors characterized by pain; histologically interlacing trabeculae of woven bone

Commonly located in the metaphysis of femur and tibia

Answer 13

Osteoid osteoma

Question 14

Tumors of Bone Quiz

Arise in vertebral transverse and spinous process

Answer 14

Osteoblastoma

Question 15

Tumors of Bone Quiz

Bony excrescences with a cartilaginous cap

Answer 15

Osteochondroma

Question 16

Tumors of Bone Quiz

Osteochondroma is associated with inactivation of this gene which encodes ___ essential for polymerization of heparan sulfate

Answer 16

EXT

Glycosyltransferase

Question 17

Tumors of Bone Quiz

Arise within the medullary cavity and erode cortex; microscopically well-differentiated cartilage-like or anaplastic

Answer 17

Chrondrosarcoma

Question 18

Tumors of Bone Quiz

Arise in medullary cavity; microscopically, sheets of small round cells that contain glycogen

Answer 18

Ewing tumor

Question 19

Tumors of Bone Quiz

Developmental defects; arise in the metaphysis of distal femur or proximal tibia. Microscopically, fibroblasts and activated macrophages in a storiform pattern

Answer 19

Fibrous cortical defect

Question 20

Tumors of Bone Quiz

Benign tumor in which all components of normal bone are present but they fail to differentiate into mature structures.

Answer 20

Fibrous dysplasia

Question 21

Most common location of fibrous dysplasia

Answer 21

Ribs

Question 22

Tumors of Bone Quiz

Well-circumscribed intramedullay lesions. Microscopically, it exhibits curved trabeculae of woven bone (mimicking Chinese characters) surrounded by fibroblastic proliferation

Answer 22

Fibrous dysplasia

Question 23

Tumors of Bone Quiz

Painful enlarging masses in the diaphyses of long tubular bones (femur); X-ray shows destructive lytic tumor with extension into surrounding tissue. Characteristic periosteal reaction depositing bone in an onionskin fashion

Answer 23

Ewing Sarcoma

Question 24

Tumors of Bone Quiz

Sheets of uniform small, round cells with scant glycogen-rich cytoplasm. Tumor cells circled around a central fibrillary space indicates neural differentiation.

Answer 24

Ewing sarcoma

with Homer-Wright rosettes

Question 25

Most common etiologic agents of suppurative arthritis: 1. Children under 2 2. Older children and adults 3. Adolescents, young adulthood 4. Sickle cell patients

Answer 25

1. Haemophilus influenzae 2. Staphylococcus aureus 3. Neisseria gonorrhea 4. Salmonella cholerasuis

Question 26

Most common site of nongonococcal suppurative arthritis

Answer 26

Knee

Question 27

Ganglion cyst is a true cyst. T/F.

Answer 27

False. It lacks a true cell lining because they arise from cystic degeneration of connective tissue.

Question 28

Most common soft tissue tumor of the hand; arises as a painless tumor of wrist and finger tendon sheats

Answer 28

Giant Cell Tumor of Tendon Sheath

Question 29

Presenting as monoarticular arthritis. Joint synovium becomes a contorted mass of red-brown folds, finger like projections and nodules

Answer 29

Pigmented villonodular tenosynovitis

Question 30

Myotonic dystrophy is inherited as an autosomal dominant trait associated with triple repeats of ___.

Answer 30

CTG; affects synthesis of an intracellular (dystrophila myotonia) protein kinase

Question 31

Muscle biopsy reveals irregular fiber with subsarcolemmal collections of mitochondria that stain red with Gomori trichome stain

Answer 31

Mitochondrial myopathy; | "ragged red fibers"

Question 32

This agent can cause proximal myopathy. The most prominent finding is myocyte vacuolization, and with progression, myocyte necrosis.

Answer 32

Chloroquine

Question 33

In MG, Thymic hyperplasia is seen in ___%. Thymoma in ___%.

Answer 33

Thymic hyperplasia in 65%; thymoma in 15%.

Question 34

Name three important differences between MG and Lambert-Eaton Myasthenic Syndrome.

Answer 34

1. Anticholinestrase does NOT improve sx. 2. Autonomic function affected. 3. Repeated stimulation elicits INCREASING muscle strength.

Question 35

Malignancy which characteristically causes Lambert-Eaton syndrome

Answer 35

Small cell lung Ca

Question 36

Which are the target of autoantibodies produced in Lambert-Eaton syndrome

Answer 36

Antibodies recognize PRE-synaptic Ca channels; leading to fewer vesicles than normal released in response to action potential.

Question 37

Most common soft tissue sarcoma of childhood

Answer 37

Rhabdomyosarcoma

Question 38

Rhabdomyosarcoma is characterized by which genetic abnormality

Answer 38

Formation of chimeric PAX3-FKHR protein which control skeletal muscle differentiation and tumor development

Question 39

Several week history of a solitary, rapidly growing mass on the volar aspect of forearm. There is positive history of trauma. Histology reveals richly cellular, plump, randomly arranged immature fibroblasts in an abundant myxoid stroma. Numerous mitotic figures are seen.

Answer 39

Nodular fasciitis | Not a true neoplasm but a reactive proliferation.

Question 40

Athletic adolescent noted swollen, painful proximal muscles after trauma. It then evolved into a painless, hard, well-demarcated mass.

Answer 40

Myositis ossificans

Question 41

Histologically, fibromatoses are composed of plump cels in broad sweeping fascicles that invade adjacent tissues. These cells are derived from:

Answer 41

Myofibroblasts

Question 42

What are desmoid tumors?

Answer 42

Aka deep fibromatoses Fibroblastic proliferations that arise in the abdominal wall and muscles of the trunk and extremities

Question 43

Soft tissue mass arising in the retroperitoneum; with soft areas of hemorrhage and necrosis. Histology reveals malignant spindle cells in a herringbone pattern

Answer 43

Fibrosarcoma

Question 44

Soft tissue mass which on histology demonstrates bizarre multinucleate cells and storiform architecture.

Answer 44

Malignant fibrous histiocytoma

Question 45

Well-dermarcated mass which on histology reveals interlacing spindle cells admixed with foamy, lipid-rich histiocyte-like cells

Answer 45

Benign fibrous histiocytoma | Dermatofibroma

Question 46

Soft tissue mass which on histology reveals spindle cells with cigar-shaped nuclei in interweaving fascicles.

Answer 46

Leiomyosarcoma

Question 47

Soft tissue tumor histology reveals two population of cells: epithelial cuboidal cells forming glands and spindle cells arranged in fascicles

Answer 47

Synovial sarcoma