MSK and CT Flashcards
Osteogenesis imperfecta is due to mutations in what?
COL1A1 and COL1A2
What are the layers of the epidermis from surface to base?
Statum corneum (keratin), lucidum, granulosum, spinosum, basale
What is the role of integrins?
Maintain integrity of basolateral membrane of epithelial cells by binding to collagen and laminin in BM
What is the role of hemidesmosomes?
Connect keratin in basal cells to underlying BM.
What is the role of desmosomes?
Structural support via keratin interactions
What is the role of e-cadherin?
Part of adherens junction - below tight junction, forms “belt” connecting actin cytoskeletons of adjacent cells. Loss of e-cadherin promotes metastasis.
What is bullous pemphigoid?
Autoantibodies to hemidesmosomes
What is pemphigus vulgaris?
Autoantibodies to desmosomes
The rotator cuff muscles are innervated primarily by which spinal nerves?
C5-C6
What is does the supraspinatus do?
(suprascapular nerve) Abducts arm initially before the action of deltoid; most common rotator cuff injury
What is does the infraspinatus do?
(suprascapular nerve) Laterally rotates arm; pitching injury
What is does the teres minor do?
(axillary nerve) Adducts and laterally rotates arm
What is does the subscapularis do?
(subscapular nerve) Medially rotates and adducts arm
What are the four muscles of the rotator cuff?
Supraspinatus, infraspinatus, teres minor, subscapularis
Dislocation of which wrist bone may cause carpal tunnel syndrome?
Lunate
What is Guyon canal syndrome?
Compression of the ulnar nerve at the wrist or hand, classically seen in cyclists
Erb palsy (“waiter’s tip”) is due to injury of what?
Traction or tear of upper trunk: C5-C6 roots
What are the causes of Erb palsy?
Infants - Lateral traction on neck during delivery
Adults - Trauma
Klumpke palsy is due to injury of what?
Traction or tear of lower trunk (C8-T1)
What are the causes of Klumpke palsy?
Infants - Upward force of arm during delivery
Adults - Trauma (grabbing a tree branch when falling)
Thoracic outlet syndrome is due to injury of what?
Compression of lower trunk and subclavian vessels
What are the causes of thoracic outlet syndrome palsy?
Cervical rib injury; Pancoast tumor
Winged scapula is due to injury of what?
Lesion of long thoracic nerve
What are the causes of winged scapula?
Axillary node dissection after mastectomy, stab wounds
Describe Type 1 muscle
Slow twitch; red fibers
Describe Type 2 muscle
Fast twitch; white fibers - weight training results in hypertrophy of these
What is the difference between endochondral ossification and membranous ossification?
Endochondral ossification needs a cartilagenous model of bone made first. Membranous does not; calvarium and facial bones.
What is the function of PTH?
At low, intermittent levels, exerts anabolic effects. Chronic high PTH levels cause catabolic effects on bone.
Describe achondroplasia
Failure of endochondral ossification (only). Constitutive activation of fibroblast growth factor receptor (FGFR3) actually inhibits chondrocyte proliferation.
What is the inheritance pattern of achondroplasia?
Most mutations occur sporadically but condition also demonstrates autosomal dominance
What are treatment options for senile osteoporosis?
Bisphosphonates, PTH, SERMs, denosumab (monoclonal Ab against RANKL)
What is osteopetrosis?
Failure of normal bone resorption due to defective osteoclasts. Thickened, dense bones that are prone to fracture. Bones fill marrow space leading to pancytopenia and extramedullary hematopoiesis.
What is a treatment option for osteopetrosis?
Bone marrow transplant is potentially curative since osteoclasts are derived from monocytes
Describe Paget disease of bone (osteitis deformans)
Common, localized disorder of bone remodeling caused by increase in both osteoblastic and osteoclastic activity. Serum Ca, phosphorus, and PTH all normal. Increased ALP. Mosaic pattern of woven and lamellar bone; long bone chalk-stick fractures. Increased blood flow from increased arteriovenous shunts may cause high-output HF. Increased risk of osteogenic sarcoma.
What is the most common site of oseteonecrosis?
Femoral head - due to insufficiency of medial circumflex femoral artery
What is the most common benign tumor of bone?
Osteochondroma
What is the MOA of bisphosphatases?
Through bloodstream, attach to bone, then osteoclasts eat bisphosphonates and apoptosis is induced in the osteoclasts. Leads to relative increase in osteoblast activity.
Osteomyelitis is seeded where in children and where in adults?
Metaphysis in kids, epiphysis in adults
Where are osteomas usually found?
Surface of facial bones
What are osteomas associated with?
Gardner syndrome
Where do osteoid osteomas usually arise?
Cortex of long bones
How does osteoid osteoma usually present?
Where are giant cell tumors of bone found?
Epiphyseal ends of long bones
What is the age range of giant cell tumors of the bone?
20-40 YO
How do giant cell tumors of the bone appear on X ray?
“Soap bubbles”
Osteochondromas are usually seen in whom?
Males
Where are osteosarcomas found?
Metaphysis of long bones, often around knee
What is the age range of osteosarcomas?
Primary: 10-20 YO. Secondary: >65 YO
What are predisposing factors of osteosarcoma?
Primary (10-20 YO): Familial RB, Li-Fraumeni, bone infarcts
Secondary (>65 YO): Paget disease of bone, radiation, bone infarcts
How does osteosarcoma appear on X ray?
Codman triangle from elevation of periosteum, or sunburst pattern
Ewing sarcoma is usually seen in whom?
Boys
Where does Ewing sarcoma usually appear?
Diaphysis of long bones, pelvis, scapula, ribs
What are the cells of Ewing sarcoma?
Poorly-differentiated cells from neuroectoderm
Ewing sarcoma is associated with what translocation?
t(11;22) translocation
Osteoblastoma is very similar to which other disease process?
Osteoid osteoma, except it does not respond to aspirin
Chondromas usually arise where?
Small bones of hands and feet
Chondrosarcomas usually arise where?
Pelvis or central skeleton
Is giant cell tumor of the bone benign or malignant?
Benign
What exactly is Rheumatoid Factor?
Anti-FcIgG IgM, associated with RA
What is gout caused by?
Precipitation of monosodium urate (MSU) crystals in joints.
Describe the birefringence of gout under polarized light
Negative birefringent (yellow under parallel light, blue under perpendicular light)
Describe the birefringence of pseudogout under polarized light
Weakly positive birefringent, blue when parallel to light
Sjogren syndrome patients have what kind of autoantibodies?
Antiribonucleoprotein Abs (Anti-SSA and anti-SSB)
Sjogren syndrome patients are at risk for which malignancy?
B cell lymphoma
Sjogren syndrome is what kind of hypersensitivity reaction?
Type IV
What are treatment options for gout?
NSAIDs (indomethacin), glucocorticoids, colchicine
What is pseudogout?
Deposition of Calcium pyrophosphate crystals within joint space
What are the symptoms of ankylosing spondylitis?
Ankylosis, uveitis, aortic regurgitation
Describe sarcoidosis
Immune-mediated widespread noncaseating granulomas and elevated serum ACE levels
What is polymyalgia rheumatica?
Pain and stiffness in shoulders and hips, often with fever, malaise, and weight loss; no muscular weakness
What is polymyalgia rheumatica associated with?
Giant cell arteritis
What kind of immune cells are seen in polymyositis?
CD8+ T cells
What exactly is inflammed in polymyositis?
Endomysium
What exactly is inflammed in dermatomyositis?
Perimysium
What kind of immune cells are seen in dermatomyositis?
CD4+ T cells
What is parakeratosis?
Hyperkeratosis (corneum) with retention of nuclei in stratum corneum
What is spongiosis?
Epidermal accumulation of edematous fluid in intercellular spaces
What is acantholysis?
Separation of epidermal cells
What is acanthosis?
Epidermal hyperplasia (spinosum)
What is melasma aka chloasma?
Hyperpigmentation associated with pregnancy or OCP use
What is Leser-Trelat sign and what can it be associated with?
Sudden appearance of multiple seborrheic keratoses, indicating an underlying malignancy (GI, lymphoid)
What is dermatitis herpetiformis?
IgA antibodies at tips of dermal papillae. Results in pruritic papules, vesicles, and bullae
What is dermatitis herpetiformis associated with?
Celiac disease. Treating the Celiac disease will treat the dermatitis.
Toxic epidermal necrolysis is the worst form of what?
Stevens-Johnson syndrome
What are actinic keratoses?
Premalignant lesions caused by sun exposure. Small, rough, erythematous or brownish papules or plaques. Risk of SCC.
What is erythema nodosum?
Painful inflammatory lesions of subcutaneous fat, usually on anterior shins. Usu idiopathic but can be associated with sarcoidosis, coccidioidomycosis, histoplasmosis, TB, streptococcal infections, leprosy, and Crohn disease
What is Lichen Planus?
6 Ps: Pruritic, Purple, Polyganol Planar Papules and Plaques. Mucosal involvement manifests as Wickham striae (reticular white lines)
What is Lichen Planus associated with?
HepC
What does Lichen Planus look like on histology?
Sawtooth infiltrate of lymphocytes at dermal-epidermal junction.
What is the most common cancer of the immunosuppressed?
Squamous cell carcinoma
What is the tumor marker of melanoma?
S-100
Metastatic or unresectable melanoma in patients with the BRAF V600E mutation may benefit from what treatment?
Vemurafenib, a BRAF kinase inhibitor
