Msk: Pathology

Front 1

Disuse atrophy findings histologically

Back 1

Angular atrophy, primarily of type II fibers

Front 2

Generally what serum marker is elevated in muscular dystrophy?

Back 2

Creatinine Kinase

Front 3

Which is the most common type of muscular atrophy?

Back 3

Duchenne muscular dystrophy

Front 4

Which protein is deficient in DMD?

Back 4

dystrophin

Front 5

Inheritance of DMD?

Back 5

X-linked (gene on short arm); as many as one third of cases de novo mutations ; mutations are variable but constant within families and lead to a DNA coding frameshift with resultant formation of stop codons and total failure of dystrophin synthesis

Front 6

What do you find on biopsy of DMD?

Back 6

Random variation in muscle fiber size, necrosis of individual muscle fibers and replacement of necrotic fibers by fibrofatty tissue

Front 7

What is the natural disease progress of DMD?

Back 7

Presents in proximal muscles of the limbs (legs and pelvis first); compensatory hypertrophy of distal sites (such as calf muscles) followed eventually by pseudohypertrophy (increased fibrous tissue and adipose tissue)

Front 8

Becker MD

Back 8

Less severe than DMD; caused by abnormality of the dystrophin molecule that is truncated and presumably less functional - not a coding frameshift

Front 9

Facioscapulohumeral MD

Back 9

AD inheritance; slowly progressive, nondisabling course and almost normal life expectancy, involes muscles of the face, scapular area and humerus

Front 10

Limb-girdle dystrophy

Back 10

AR; involves the proximal muscles of the shoulder, pelvic girdle or both

Front 11

Myotonic dystrophy

Back 11

AD; weakness associated with myotonia; features include cataracts, as well as testicular atrophy and baldness in men; caused by increased number of trinucleotide repeats (CTG in myotonin protein kinase gene)

Front 12

Congenital myopathies (3) - i.e. floppy infant syndrome

Back 12

Central core disease - loss of mit and other organelles in the central portion of type I muscles fibers; characterised by muscle weakness and hypotonia but affected infants eventually become ambulatory

Nemaline myopathy - tangles of small rod-shaped granules in type I fibers; varies from mild nonprogressive to severe -- death from resp failure

Mitochondrial myopathies - maternally transmitted mit DNA abnormalities; ragged red appearance of muscle bibers and various mit enzyme or coenzyme defects

Front 13

Myasthenia Gravis

Back 13

autoantibodies to Ach R in the NMJ; 3x more women; muscle weakness intensified by muscle use, with recovery on rest; frequently associated with tumors of the thymus or with thymic hyperplasia!

Front 14

Lambert-Eaton Syndrome

Back 14

paraneoplastic disorder (small cc of the lung); caused by defect in the release of Ach by nerve cells; may be due to acquired autoantibodies that react with presynaptic voltage-gated calcium channels

**Clinically: strength gets better on repeat testing**

Front 15

What clinical associations are there to osteoporosis?

Back 15

Postmenopausal state; physical inactivity; hypercorticism; HYPERTHYROIDISM; calcium deficiency

Front 16

von Recklinghausen disease of the bone (osteitis fibrosa cystica)

Back 16

caused by primary or secondary hyperparathyroidism; widespread osteolytic lesions; "brown tumor"; hyperparathyroidism, high serum calcium, low serum phosphorus and high serum alk phos

Front 17

Osteomalacia

Back 17

Vit D deficiency in adults; defective calcification of osteoid matrix is characteristic; diffuse radiolucency which can mimic osteoporosis is characteristic radiographically; called renal osteodystrophy when secondary to renal disease

Front 18

Rickets

Back 18

Vit D deficiency in children; decreased calcification and excess accumulation of osteoid --> increased thickening of the epiphysial growth plates; clinical manifestations include craniotabes, late closing of the fontanelles, rachitic rosary, harrison groove, pigeon breast, decreased height

Front 19

Paget Disease of bone

Back 19

Abnormal bone architecture caused by increases in both osteoblastic and osteoclastic activity; marked increase in serum alk phos (osteoblastic activity)

Front 20

What are the complications of Pagets?

Back 20

Bone pain from fractures; high-output cardiac failure; hearing loss; osteosarcoma (1%)

Front 21

Bone changes associated with scurvy

Back 21

Subperiosteal hemorrhage, osteoporosis, epiphyseal cartilage not replaced by osteoid

Front 22

Pathogenesis of scurvy

Back 22

Failure of proline and lysine hydroxylation required for collagen synthesis --> impaired osteoid matrix formation

Front 23

Achondroplasia

Back 23

AD mutation in the fibroblast growth factor receptor 3 gene; failure of elongation

Front 24

Fibrous dysplasia 3 main types

Back 24

Monostotic fibrous dysplasia, polyostotic fibrous dysplasia & McCune-Albright syndrome (polyostotic fibrosis dysplasia, precocious puberty, cafe-au-lait spots on skin and short stature, occurring in very young girls

Front 25

Where can avascular necrosis involve in growing children?

Back 25

Head of femur = Legg-calve-perthes disease; tibial tubercle (osgood-schlatter disease) or the navicular bone (kohler bone disease)

Front 26

Osteogenesis imperfecta

Back 26

multiple fractures occurring with minimal trauma; blue sclerae; AD variant most common

Front 27

Osteopetrosis also known as...

Back 27

Albers-Schonberg disease or marble bone

Front 28

Pathology of osteopetrosis

Back 28

Failure of osteoclastic activity due to deficiency of carbonic anhydrase; AR form that is fatal in infancy and a less severe AD form

Front 29

Pyogenic Osteomyelitis (in children)

Back 29

Occurs most often as a result of BB spread from an infection elsewhere; staph aureus is most common, group B strep or ecoli are frequent in newborns, salmonella is frequent in association with sicle cell anemia

Front 30

Pyogenic osteomyelitis (adults)

Back 30

Usually a complication of a compound fracture ore a sequela of surgery; in IVDU, pseudomonas

Front 31

What are the most common sites of osteomyelitis?

Back 31

initially involves the metaphysis; the distal end of the femur, proximal end of the tibia and proximal end of humerus

Front 32

Pott disease

Back 32

tuberculosis osteomyelitis in vetebrae --> collapse --> deformity

Front 33

Histiocytosis X

Back 33

can occur in a variety of sites including bone; histiocytic cells closely resemble the Langerhans cells of the epidermis; Birbeck granules