Bone and Joints pathology Flashcards
1
Q
Denervation atrophy
A
- Involved both type I (red) and type II (white) fibers
- Target fibers may also be seen
- After reinnervation - fiber-type grouping, clusters of type I and type II, may be seen
2
Q
Difuse atrophy
A
- Associated with prolonged immobilization
- Characterized by angular atrophy, primary of type II fibers
3
Q
Duchenne muscular dystrophy
A
- Most common and most severe of the muscular dystrophies
- Replacement of skeletal muscle by adipose tissue
- Begins with weakness in the proximal muscles of the extremities –> immobilization, wasting, muscle contracture, and death in early teens
- Caused by deficiency of dystrophin - X-linked inheritance
- Random variation in muscle fiber size, necrosis of individual muscle fibers, and replacement of necrotic fibers by fibrofatty tissue
- Characterized by calf pseudohypertrophy
- Serum creatine kinases is elevated
4
Q
Becker muscular dystrophy
A
- Clinical similar, but less severe than, Duchenne muscular dystrophy
- Caused by abnormality in dystrophin - molecule is truncated and presumably less functional
- Caused by segmental deletions within the gene that do not cause a coding frameshift
5
Q
Facioscapulohumeral muscular dystrophy
A
- Autosomal dominant inheritance
- Associated with slowly progressive, nondisabling course and an almost-normal life expectancy
- Involves muscles of face, scapular area, and humerus
6
Q
Limb-girdle dystrophy
A
- Autosomal recessive inheritance
- Involves proximal muscles of the shoulder, pelvic girdle, or both
7
Q
Myotonic dystrophy
A
- Autosomal dominant mode of inheritance
- Weakness associated with myotonia (inability to relax muscles once contracted)
- Associated features include cataracts, as well as testicular atrophy and baldness in men
- Caused by increased number of trinucleotide repeats - CTG repeats
8
Q
Central core disease
A
- Loss of mitochondria and other organelles in he central portion of type I muscle fibers
- Characterized by muscle weakness and hypotonia
- Affected infants eventually become ambulatory
9
Q
Nemaline myopathy
A
- Tangles of small rod-shaped granules, predominantly in type I fibers
- Varies clinically from a mild, nonprogressive disease to severe weakness ending in death from respiratory failure
10
Q
Mitochondrial myopathies
A
- Non-Mendelian inheritance
- Mediated by maternally transmitted mitochondrial DNA abnormalities
- May be characterized by ragged red appearance of muscle fibers and by various mitochondrial enzyme or coenzyme defects
11
Q
Myasthenia gravis
A
- Autoimmune disorder
- Caused by antoantibodies to postsynaptic acetylcholine receptors of the neuromuscular junction
- More common in women
- Characterized by muscle weakness intensified by muscle use, with recovery on rest
- Involves extraocular and facial muscles, muscles of the extremities, and other muscle groups
- Ptosis or diplopia, difficulty in chewing, speaking, or swallowing
- Symptoms improve with anticholinesterase agents
- Associated with tumors of the thymus or with thymic hyperplasia
12
Q
Lambert-Eaton syndrome
A
- Paraneoplastic disorder - most commonly associated with small cell carcinoma of the lung
- Caused by a defect in the release of acetylcholine by nerve cells
- May be due to acquired autoantibodies that react with presynaptic voltage-gated calcium channels
13
Q
Osteoporosis
A
- Characterized by a decrease in bone mass due to loss of bone matrix
- May be caused by impaired synthesis or increased resorption of bone matrix protein
- Most common bone disorder in older persons
- Results in bone structures inadequate for weight bearing - fractures commonly occur
- Assocaited with postmenopausal state and estrogen deficiency
- Present with fractures, kyphosis, and shortened stature
- Predisposed by: postmenopausal state, physical inactivity, hypercorticism, hyperthyroidism, calcium deficiency
14
Q
von Recklinghausen disease of bone (osteitis fibrosa cystic)
A
- Caused by primary or secondary hyperparathyroidism
- May manifest as “brown tumor” of bone
- Can be morphologically indistinguishable from giant cell tumor of bone
- Lab: hyperparathyroidism, high serum calcium, low serum phosphorus, and high serum alkaline phosphatase occur
15
Q
Osteomalacia
A
- Vitamin D deficiency in adults
- Characterized by defective calcification of osteoid matrix
- Result in weak bone with increased risk for fracture
- Lab: decreased serum calcium and serum phosphate, increased PTH and alkaline phosphatase
- When secondary to renal disease, osteomalacia is called renal osteodystrophy
16
Q
Rickets
A
- Vitamin D deficiency in children
- Increased thickness of the epiphyseal growth plates and other skeletal deformities
- Clinical: Craniotabes, late closing of fontanelles, rachitic rosary, harrison groove, pigeon breast, decreased hight
17
Q
Paget disease of bone
A
- Most common in the elderly
- Imbalance between osteoclast and osteoblast function
- Etiology is unknown; possibly viral
- Localized process involving one or more bones; does not involve entire skeleton
- Involves most commonly the spine, pelvis, calvarium of the skull, femur, and tibia
- Stages; (1) Osteoclastic, (2) Mixed osteoblastic - osteoclastic (3) Osteoblastic
- End result is thick sclerotic bone that fractures easily
- Complications: bone pain resulting from fractures, high-output cardiac failure, hearing loss, osteosarcoma
