PATH - General Flashcards
Achondroplasia
autosomal dominant with full penetrance
Failure of longitudinal bone growth (endochondral ossification)–>short limbs
activation of fibroblast
growth factor receptor (FGFR3)
Osteoporosis
Trabecular (spongy) and cortical bone *lose mass and interconnections despite normal bone mineralization and lab values (serum Ca2+ and
PO43−).
Can lead to *vertebral compression fractures
- Most commonly due to INC bone resorption related to DEC estrogen levels (Type I-postmenopausal) and old age (Type II-Senile).
- Can be secondary to drugs or other medical conditions
*bone mineral density scan with a T-score of ≤ −2.5 or by a fragility fracture of hip or vertebra.
Osteopetrosis (marble bone disease)
Failure of normal bone resorption due to defective osteoclasts–>thickened, *dense bones that are prone to fracture.
X-rays show bone-in-bone (“stone” bone) appearance
Mutations (eg, *carbonic anhydrase II) impair ability of osteoclast to generate acidic environment necessary for bone resorption
Osteomalacia/Rickets
Most commonly due
to *vitamin D deficiency
Defective mineralization of osteoid (osteomalacia) or cartilaginous growth plates
(rickets, only in children)
Children with rickets have bow legs, bead-like costochondral junctions (rachitic rosary), craniotabes (soft skull).
X-rays show osteopenia and “Looser zones” (pseudofractures) in osteomalacia, epiphyseal
widening and metaphyseal cupping/fraying in
rickets.
DEC vitamin D–>DEC serum Ca2+–>INC PTH secretion–>DEC serum PO43−.
Hyperactivity of osteoblasts–>INC ALP
Paget disease of bone
osteitis deformans
Common, localized disorder of bone remodeling caused by INC osteoclastic activity
followed by INC osteoblastic activity that forms poor-quality bone.
Mosaic pattern of woven and lamellar bone
-*Hat size can be increased due to skull thickening
-hearing loss is common due to
auditory foramen narrowing
INC Risk
- long bone chalk-stick fractures
- osteogenic sarcoma
INC ALP
Stages of Paget disease: -Lytic—osteoclasts -Mixed—osteoclasts+osteoblasts -Sclerotic—osteoblasts -Quiescent—minimal osteoclast/osteoblast activity
Osteonecrosis (avascular necrosis)
Infarction of bone and marrow, usually very painful.
Most common site is *femoral
head
Osteoarthritis
Mechanical—wear and tear destroys articular cartilage (“degenerative joint disease”).
Chondrocytes mediate degradation and inadequate repair.
- Pain in weight-bearing joints *after use, improving with rest
- Asymmetric joint involvement
- Knee cartilage loss begins medially (“bowlegged”)
- *No systemic symptoms.
- Osteophytes (bone spurs)
- joint space narrowing
- subchondral sclerosis and cysts
- Involves DIP (Heberden nodes) and PIP (Bouchard nodes), and 1st CMC; not MCP.
Rheumatoid arthritis
Autoimmune—inflammatory cytokines and cells induce *pannus formation, which erodes articular cartilage and bone
-Pain, swelling, and morning stiffness lasting > 1 hour, improving with use
-Symmetric joint involvement
-*Systemic symptoms
(fever, fatigue, weight loss)
-Extraarticularmanifestations common
-Deformities include subluxation, fingers with ulnar deviation, swan neck, and boutonniere
-Synovial fluid inflammatory
-Involves MCP, PIP,
wrist; not DIP or 1st CMC.
*HLA-DR4
smoking, silica exposure
- ⊕ rheumatoid factor (anti-IgG antibody; in 80%)
- anti-cyclic citrullinated peptide antibody (more specific).
Gout
Acute inflammatory monoarthritis caused by precipitation of *monosodium urate crystals in joints
Associated with hyperuricemia
Crystals are needle shaped and ⊝ birefringent under polarized light (yellow under parallel light,
blue under perpendicular light
-painful MTP joint of big toe (podagra)
-Tophus formation (often on external ear, olecranon bursa, or
Achilles tendon)
Pseudogout
Deposition of *calcium pyrophosphate crystals within the joint space
Crystals are *rhomboid and weakly ⊕ birefringent under polarized light (blue when parallel to light)
Pain and swelling with acute inflammation (pseudogout) and/or chronic degeneration (pseudoosteoarthritis).
Knee most commonly affected joint
Sjögren syndrome
Autoimmune disorder characterized by destruction of exocrine glands (especially
lacrimal and salivary)
Findings:
- Inflammatory joint pain
-Keratoconjunctivitis sick (DEC tear production and subsequent corneal damage)
-Xerostomia (DEC saliva production)
-Presence of antinuclear antibodies: *SS-A (anti-Ro) and/or *SS-B (anti-La)
-Bilateral parotid enlargement
Complications: dental caries; mucosa-associated lymphoid tissue (MALT) lymphoma (may present as parotid enlargement).
Predominantly affects females
40–60 years old.
Septic arthritis
Medical Emergency!
S aureus, Streptococcus, and Neisseria gonorrhoeae are common causes.
Affected joint is swollen, red, and painful.
Synovial fluid purulent (WBC > 50,000/mm3).
*Gonococcal arthritis—STI that presents as either purulent arthritis (eg, knee) or triad of
polyarthralgias, tenosynovitis (eg, hand), dermatitis (eg, pustules).
Ankylosing spondylitis
Symmetric involvement of spine and sacroiliac joints–>ankylosis (joint fusion), uveitis, aortic
regurgitation
*Bamboo spine (vertebral fusion)
Arthritis *without rheumatoid factor (no anti-IgG antibody).
Strong association with *HLA-B27 (MHC class I serotype)
Reactive arthritis
AKA Reiter syndrome
Classic triad:
Conjunctivitis
Urethritis
Arthritis
“Can’t see, can’t pee, can’t bend my knee.”
Systemic Lupus Erythematous
RASH OR PAIN: Rash (malar or discoid) Arthritis (nonerosive) Serositis Hematologic disorders (eg, cytopenias) Oral/nasopharyngeal ulcers Renal disease Photosensitivity Antinuclear antibodies Immunologic disorder (anti-dsDNA, anti-Sm, antiphospholipid) Neurologic disorders (eg, seizures, psychosis)
Common causes of death in SLE:
*Cardiovascular disease
-Libman-Sacks Endocarditis—nonbacterial, verrucous thrombi usually on mitral or aortic
valve ("LSE in SLE").
*Infections
*Renal disease
-Lupus nephritis can be nephritic
or nephrotic (hematuria or proteinuria).
