Musculoskeletal System Flashcards
Uniformly fatal variant of osteogenesis imperfecta
Type II OI
The underlying etiology in achondroplasia is a point mutation in the ___ that results in its constitutive activation and inhibits chondrocyte proliferation.
Fibroblast growth factor 3
A variant of osteopetrosis is characterized by deficiency in ____ necessary for osteoclast hydrogen ion secretion and bone acidification.
Carbonic anhydrase II
Complications of osteopetrosis
Fractures
Cranial nerve deficits (from compression of surrounding bone)
Recurrent infections
Hepatosplenomegaly (extramedullary hematopoiesis)
Which is more effective in increasing bone mass?
A. Resistance exercises (weight training)
B. Endurance activities (jogging)
A. The magnitude of skeletal loading is more important than the number of load cycles.
What are two factors that conspire to convert macrophages into osteoclasts?
RANK (RANK-R in macrophages; RANK expressed by stromal cells)
M-CSF (secreted by osteoblasts)
Pathognomonic histologic feature of Paget disease
Mosaic pattern of lamellar bone
Paget disease is associated with ___ infection.
Paramyxovirus
Cytokines produced in large amounts in pagetic bone.
IL-1
M-CSF
Collections of osteoclasts, reactive giant cells, and hemorrhagic debris form a distinct mass termed ___.
Brown tumor of hyperparathyroidism
Osteonecrosis Quiz
A. Subchondral infarct
B. Medullary infarct
- Pain during physical activity
- Stable
- A
2. B
Favored bony sites of hematogenous spread of TB.
Long bones
Vertebrae
Tumors of Bone Quiz
Cortical tumors characterized by pain; histologically interlacing trabeculae of woven bone
Commonly located in the metaphysis of femur and tibia
Osteoid osteoma
Tumors of Bone Quiz
Arise in vertebral transverse and spinous process
Osteoblastoma
Tumors of Bone Quiz
Bony excrescences with a cartilaginous cap
Osteochondroma
Tumors of Bone Quiz
Osteochondroma is associated with inactivation of this gene which encodes ___ essential for polymerization of heparan sulfate
EXT
Glycosyltransferase
Tumors of Bone Quiz
Arise within the medullary cavity and erode cortex; microscopically well-differentiated cartilage-like or anaplastic
Chrondrosarcoma
Tumors of Bone Quiz
Arise in medullary cavity; microscopically, sheets of small round cells that contain glycogen
Ewing tumor
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
Fibrous cortical defect
Tumors of Bone Quiz
Benign tumor in which all components of normal bone are present but they fail to differentiate into mature structures.
Fibrous dysplasia
Most common location of fibrous dysplasia
Ribs
Tumors of Bone Quiz
Well-circumscribed intramedullay lesions. Microscopically, it exhibits curved trabeculae of woven bone (mimicking Chinese characters) surrounded by fibroblastic proliferation
Fibrous dysplasia
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
Ewing Sarcoma
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.
Ewing sarcoma
with Homer-Wright rosettes
Most common etiologic agents of suppurative arthritis:
- Children under 2
- Older children and adults
- Adolescents, young adulthood
- Sickle cell patients
- Haemophilus influenzae
- Staphylococcus aureus
- Neisseria gonorrhea
- Salmonella cholerasuis
Most common site of nongonococcal suppurative arthritis
Knee
Ganglion cyst is a true cyst. T/F.
False. It lacks a true cell lining because they arise from cystic degeneration of connective tissue.
Most common soft tissue tumor of the hand; arises as a painless tumor of wrist and finger tendon sheats
Giant Cell Tumor of Tendon Sheath
Presenting as monoarticular arthritis. Joint synovium becomes a contorted mass of red-brown folds, finger like projections and nodules
Pigmented villonodular tenosynovitis
Myotonic dystrophy is inherited as an autosomal dominant trait associated with triple repeats of ___.
CTG; affects synthesis of an intracellular (dystrophila myotonia) protein kinase
Muscle biopsy reveals irregular fiber with subsarcolemmal collections of mitochondria that stain red with Gomori trichome stain
Mitochondrial myopathy;
“ragged red fibers”
This agent can cause proximal myopathy. The most prominent finding is myocyte vacuolization, and with progression, myocyte necrosis.
Chloroquine
In MG,
Thymic hyperplasia is seen in ___%.
Thymoma in ___%.
Thymic hyperplasia in 65%; thymoma in 15%.
Name three important differences between MG and Lambert-Eaton Myasthenic Syndrome.
- Anticholinestrase does NOT improve sx.
- Autonomic function affected.
- Repeated stimulation elicits INCREASING muscle strength.
Malignancy which characteristically causes Lambert-Eaton syndrome
Small cell lung Ca
Which are the target of autoantibodies produced in Lambert-Eaton syndrome
Antibodies recognize PRE-synaptic Ca channels; leading to fewer vesicles than normal released in response to action potential.
Most common soft tissue sarcoma of childhood
Rhabdomyosarcoma
Rhabdomyosarcoma is characterized by which genetic abnormality
Formation of chimeric PAX3-FKHR protein which control skeletal muscle differentiation and tumor development
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.
Nodular fasciitis
Not a true neoplasm but a reactive proliferation.
Athletic adolescent noted swollen, painful proximal muscles after trauma. It then evolved into a painless, hard, well-demarcated mass.
Myositis ossificans
Histologically, fibromatoses are composed of plump cels in broad sweeping fascicles that invade adjacent tissues. These cells are derived from:
Myofibroblasts
What are desmoid tumors?
Aka deep fibromatoses
Fibroblastic proliferations that arise in the abdominal wall and muscles of the trunk and extremities
Soft tissue mass arising in the retroperitoneum; with soft areas of hemorrhage and necrosis. Histology reveals malignant spindle cells in a herringbone pattern
Fibrosarcoma
Soft tissue mass which on histology demonstrates bizarre multinucleate cells and storiform architecture.
Malignant fibrous histiocytoma
Well-dermarcated mass which on histology reveals interlacing spindle cells admixed with foamy, lipid-rich histiocyte-like cells
Benign fibrous histiocytoma
Dermatofibroma
Soft tissue mass which on histology reveals spindle cells with cigar-shaped nuclei in interweaving fascicles.
Leiomyosarcoma
Soft tissue tumor histology reveals two population of cells: epithelial cuboidal cells forming glands and spindle cells arranged in fascicles
Synovial sarcoma
