MSK Flashcards

Question

Which is true regarding rheumatoid arthritis? (March 2014) a. It has no gender predilection b. Commonly involves the axial skeleton c. The joints of the feet are often spared d. Rheumatoid nodules affect the heart valves

Answer 1

• Rheumatoid arthritis has a female predominance (2-3:1) • Most commonly affected joints are the hands & wrists initially, then the feet & larger joints • Rheumatoid assoc valvular heart disease: o Typically left sided o Characterised by nodules & valve thickening ANSWER: Rheumatoid nodules affect the heart valves

Answer 2

ANSWER: Rheumatoid arthritis is more commonly seen in females (30-50)

Answer 3

``` Morphological features of rheumatoid arthritis o Inflammation o Pannus o Eroding cartilage o Fibrous ankylosis o Bony ankylosis ``` Compared to RA, JIA more commonly has these features: o Oligoarthritis o Systemic disease is more frequent o Large joints are more affected than small joints o Rheumatoid nodules & RF are usually absent o ANA seropositivity is common ``` Subgroups of JIA: o Systemic o Polyarticular RF positive o Enthesitis-related (involvement at sites of ligament & cartilage insertion on bone) o Oligoarticular ``` ANSWER: Enthesitis

Answer 4

* JIA patients are usually RF & Anti-CCP negative * The subgroup of patients who are RF positive often also have a positive Anti-CCP ANSWER: JIA patients are typically negative for RF AND Anti-CCP

Answer 5

Reactive arthritis is a transient arthritis which occurs after infection which typically affects 1 or 2 large joints o Considered a seronegative arthritis o HLA-B27 positive in 80% Classic triad consists of: (<1/3 have the full triad at diagnosis) o Arthritis - Heel pain is often the most disabling feature o Conjunctivitis o Urethritis (or cervicitis in women) Causes: o Enteric infections: Yersinia, Campylobacter, Salmonella, Shigella or less commonly E. Coli o Sexually transmitted: Chlamydia o Other: Brucellosis Epidemiology: o Male predilection (5-6:1) Location: o Small joints of the feet: 64% o Sausage digits: 52% o Low back pain: 61% (but radiological changes in 20% only) Radiographic changes: o Feet: Calcaneus (classic location) • Early: posterior tubercle deossification • Later: posterior tubercle erosions & enthesitis. Sausage digit, periostitis (especially toes) o Axial: - Bilateral (often symmetric) sacro-illitis - Bulky paravertebral ossification • Asymmetric • May only involve one side • Skip bodies ANSWER: All are typical causes of reactive arthritis

Answer 6

ANSWER: Reactive arthritis is commonly seen following gastrointestinal infections. Yersina, Campylobacter & Salmonella are most common.

Answer 7

Musculoskeletal SLE: o Present in 75-90% of patients w varying severity o Symmetric polyarthritis ``` Locations: • Small joints of the hand • Knees • Wrists • Shoulders ``` Features: • Deforming non-erosive arthropathy - Ligamentous laxity & muscular contracture - Deformities are frequently reducible & less commonly disabling • Periarticular osteoporosis • Preserved joint spaces • Carpal instability in 15% o Spine: atlantoaxial subluxation in 10% o Myositis: 30-50% observed clinically, but true myositis in 4% o Osteonecrosis: - Femoral head most common, but any site can be involved - May be seen as part of the disease (particularly younger patients w Raynaud phenomenon) or as a complication of steroid treatment o Soft tissue calcification o Insufficiency fracture o Osteomyelitis & septic arthritis - Increased incidence due to steroid use & CRF ANSWER: Erosions are not seen in SLE arthropathy

Answer 8

More common causes of viral assoc arthritis: o EBV o Adenovirus & enterovirus o Parvovirus B19 – adult presentation may be w arthralgia & arthritis o Hepatitis A o Hepatitis B – sudden onset, transient polyarthritis which mimics RA, typically accompanied by a rash o Hepatitis C – 2-5% of chronic HCV develop an inflammatory oligo or polyarthritis which mimics RA but is not destructive o Ross River Virus & Barmah Forest Virus o Measles, mumps, rubella • CMV, HSV & varicella are uncommon causes of arthritis ANSWER: CMV does not typically cause arthritis

Answer 9

Gout o Transient attacks of acute arthritis initiated by crystallization of urates around joints -> Leads to chronic gouty arthritis & tophi w repeated attacks o Results from abnormalities of uric acid synthesis or excretion Synthesis: • Uric acid is the end product of purine metabolism • Increased uric acid typically reflects abnormal purine metabolism Excretion: • Uric acid is filtered from the blood by the glomeruli & almost entirely resorbed by the proximal tubule • Small fraction is secreted by the distal nephrons into urine o Primary gout: Increased uric acid biosynthesis o Secondary gout: Increased production of uric acid (e.g. rapid cell lysis) or decreased excretion (e.g. chronic renal disease) o Joint disease: - Deposition of MSU (monosodium urate) crystals in the joint - Macrophages ingest the crystals & trigger an acute inflammatory response • Proinflammatory cytokines, cell recruitment • Urate crystals also activate the complement system - Acute inflammation which remits following days/weeks Factors influencing the conversion of hyperuricaemia to gout: - Patient age - Duration of elevated uric acid - Heavy alcohol consumption - Obesity - Drugs e.g. thiazides - Toxins e.g. lead Morphology: Acute arthritis • Dense neutrophilic infiltrate w/in the synovium & synovial fluid • Slender, needle-like crystals w POSITIVE birefringence • Oedematous & congested synovium • Scattered chronic inflammation Chronic tophaceous arthritis • Urates can encrust the articular surfaces - Synovial deposits • Hyperplastic & fibrotic synovium - Increased inflammatory infiltrates • Synovial pannus extends from the cartilage to the juxta-articular bone - Erosions, fibrosis, eventual bony ankylosis Tophi: • Pathognomonic lesions • Masses of urates surrounded by an intense mononuclear inflammatory reaction - Foreign body giant cells • Common locations: ear, olecranon & patella bursae, periarticular ligaments & connective tissue Gouty nephropathy: • Deposition of monosodium urate crystals in the renal medulla • Uric acid stones • Obstruction can lead to secondary pyelonephritis Clinical course: - Chronic gout develops after years of episodes of acute gout (12 years average) - Accompanying cardiovascular disease common – atherosclerosis & HTN - 20% of patients die of secondary renal failure ANSWER: 20% of patients die of renal failure (rather than 10%); calcium oxalate stones are seen in Crohn disease

Answer 10

Calcium pyrophosphate crystal deposition disease Epidemiology: - Typically occurs after age 50 - Hereditary variants present earlier (e.g. AD form). - 30-60% prevalence by age 85 ``` Associations with the secondary form: Trauma Hyperparathyroidism Haemochromatosis Diabetes ``` Clinical: Presentation similar to acute gout Pathology: - Altered matrix synthesis & degradation of pyrophosphates - Crystals initially deposit in cartilage - Deposits enlarge & rupture into and seed the joint - Macrophages engulf the crystals & initiate a strong inflammatory response - Recruitment of neutrophils - Joint damage in 50% - Crystals form chalky white, friable deposits. Rarely form large masses - Crystals stain as oval blue-purple aggregates - Weak positive birefringence, Geometric shapes - Chronic lesions show mononuclear cell infiltrates & fibrosis ``` Location: Knees (most common) Wrists (TFCC calcification) Elbows Shoulders Ankles ``` ANSWER: CPPD is assoc w hyperparathyroidism

Answer 11

• Crystals are have weak positive birefringence ``` Joints affected (decreasing order): o Knees o Wrists o Elbows o Shoulders o Ankles ``` ``` Causes of secondary CPPD: o Trauma o Hyperparathyroidism o Haemochromatosis o Diabetes ``` Pathology: o Altered matrix synthesis o Degradations of pyrophosphates o Crystals form in the cartilage as aggregates, elicit an inflammatory response when they seed into the joint ANSWER: Secondary CPPD is assoc w haemochromatosis; the ankles are affected but not the most common joint

Answer 12

ANSWER: Pubic symphisis calcification – the patient has CPPD & there is chondrocalcinosis of the pubic symphysis fibrocartilage.

Answer 13

HADD – broad spectrum of musculoskeletal pathology due to deposition of hydroxyapatite deposition o Homogenous calcification located at a tendon or a bursa o Generally monoarticular Location: - Shoulder (most common): supraspinatus & biceps tendon - External rotators of the hip: Gluteus medius tendon most common, may also involve gluteus maximus - Less common: spine (longus coli & ligamentum flavum), elbow, knee, wrist & ankle Characteristics of calcifications change overtime: - Faint, Dense, May eventually resorb Primary vs secondary: Primary: tendinosis & bursitis Secondary: end-stage renal disease, collagen vascular disease (dermatomyositis & scleroderma), vitamin D intoxication, tumoral calcinosis o Assoc w osteoarthritis - Milwaulkee shoulder is an extension of this, which causes rapid destructive arthropathy of the shoulder joint ANSWER: HADD does not occur at the tendon insertions in psoriatic arthritis. Scleroderma & dermatomyositis are causes of secondary hydroxyapatite deposition. The shoulder and hip flexors are common sites of involvement. **May be “which is true” – most correct is progressive destruction in the shoulder (Milwaulkee shoulder)

Answer 14

Localised giant cell tumour of the tendon sheath o Circumscribed proliferation of synovial like mononuclear cells w osteoclast like giant cells, foam cells, siderophages & inflammatory cells - Usually in the fingers - Second most common tumour of the hand after ganglion cysts - Slow growing, painless mass (usually 2-5cm) Epidemiology: - 30-50 years. Females more commonly Diffuse giant cell tumour of the tendon sheath o Extra-articular, destructive villonodular hyperplasia w synovial mononuclear cells, multinucleated giants cells, foam cells, siderophages & inflammatory cells o Soft tissue counterpart of pigmented villonodular synovitis (PVNS) -> PVNS occurs near a joint Epidemiology: - Rare. Females, <40 years Features: - Most commonly around the knee (80%) - Almost always mono-articular - May be locally aggressive & invade underlying bone & cartilage (hypoplastic, not neoplastic) ANSWER: When localised, giant cell tumour of the tendon sheath is usually confined to the hand

Answer 15

ANSWER: Fat

Answer 16

Inflammatory myopathies o DERMATOMYOSITIS - Autoimmune disease of the skin & muscle • Capillaries are the primary target of autoantibodies, including Jo1, Mi2 and PI55/P140 Early findings: • Heliotrope rash: lilac rash of upper eyelids • Periorbital oedema Later disease manifestations: • Weakness - Insidious onset, bilateral & symmetric. Proximal muscles affected first. Dysphagia in 1/3 • Scaling of the skin • Gottron papules: erythematous patches over knuckles, elbows & knees • Other: ILD, vasculitis & myocarditis Associations: • Calcinosis in 1/3 • Paraneoplastic syndrome in 15-25% of adults • GI symptoms in children - Responsive to immunosuppressive therapy o POLYMYOSITIS - Primarily affects adults - Similar features to dermatomyositis but no cutaneous involvement - Driven by T-cell mediated myocyte damage - Responsive to immunosuppressive therapy o INCLUSION BODY MYOSITIS - Begins as distal muscle involvement, particularly the quadriceps & distal upper limbs • Dysphagia 50% • Insidious onset Epidemiology: • Patients usually over 50 • Most common acquired neuropathy in patients >50 • Male predominance Pathology: • Thought to be due to intracellular deposition of abnormally folded proteins. Form inclusion bodies in the nuclei & cytoplasm of affected cells • Most myositis antibodies are absent - Immunosuppressive therapies are of limited benefit Associations: • Diabetes mellitus (20%) • Other autoimmune conditions (15%) • Inflammatory myositis is a rare cause of myoglobinuria, more commonly assoc w rhabdomyolysis ANSWER: Glomerulosclerosis may be the correct answer as it is assoc w diabetes (as is inclusion body myositis); helitrope rash & ‘cancer’ (paraneoplastic syndromes) are assoc w dermatomyosits; myoglobinuria is rare

Answer 17

``` Most common primary retroperitoneal malignancies: o Liposarcoma o Myxofibrosarcoma o Leiomyosarcoma o Rhabdosarcoma o Fibrosarcoma ``` Retroperitoneal sarcoma may occur secondary radiotherapy or treatment for neuroblastoma ANSWER: Lipsarcoma is the most common retroperitoneal malignancy

Answer 18

Nodular fasciitis o Non-neoplastic lesions which are either idiopathic or develop in response to trauma (25%) o Can grow rapidly & may have high cellularity, mitotic rate & numbers of reactive mesenchymal cells - Clonal proliferation, but limited. t(17;22) Locations: flexor forearm, chest, back or elsewhere Morphology: - Large, nodular neoplasms w ill-defined margins Microscopic: - Cellular & highly mitotic - Plump immature fibroblasts & myofibroblasts - Myxoid stroma & scattered lymphocytes Myositis ossificans o Focal intramuscular lesion composed of fibrous tissue & metaplastic bone Epidemiology: - Young, active males - 60-75% have a history of recent trauma - Also occur after elective surgery, severe burns & neurologic impairment Sites: upper extremity flexors, quadriceps, thigh adductors, gluteal muscles, soft tissues of the hand ANSWER: ?d – myositis ossificans may not have well defined borders in the acute phase

Answer 19

FIBROMATOSIS: o Encompasses a wide range of soft tissue lesions which share an underlying histopathological pattern of fibrous tissue proliferation o Vary in behaviour, from benign to malignant Examples - Benign: nodular fasciitis, proliferative fasciitis & myositis, myositis ossificans, elasto-fibroma, fibromatosis coli - Intermediate (locally aggressive): superficial fibromatoses (palmar & plantar), dermoid type fibromatoses - Intermediate (rarely metastasizing): solitary fibrous tumour, haemangiopericytoma, inflammatory myofibroblastic tumour - Malignant: myxofibrosarcoma PLANTAR FIBROMATOSIS: o Benign fibroblastic proliferation of the plantar fascia - Musculoskeletal fibromatosis o Children & adults, more common in males Clinical: - Middle or medial aspect of the plantar arch - Symptomatic from mass effect or local invasion of the muscle or adjacent neurovascular bundle - Flexion deformities do not usually occur (as w palmar fibromatosis) Associations: - Dupuytren’s disease (plantar fibromatosis) – 40% - Keloids - Peyronie disease ``` PEYRONIE DISEASE (fibromatosis of the penis): o Fibrous plaques form in the tunica albuginea which causes painful shortening & deformity of the penis - Plaques are usually seen on the dorsal aspect, but less commonly are present ventrally - Radiology used to examine the extent of the plaques & for possible involvement of the penile septum & the neuromuscular bundles (but Dx is clinical) - Cause of erectile dysfunction, esp if there is neuromuscular bundle involvement ``` Epidemiology: males 50-60 years ``` Associations:  Plantar fibromatosis  Dupuytren’s disease  Penile trauma  Diabetes  Beta-blockers  Paget’s disease of bone  Phenytoin ``` INTRA-ABDOMINAL FIBROMATOSIS: o Mesenteric, pelvic or retroperitoneal Associations: Post surgical Gardner’s syndrome Pregnancy – during or after, may see w C-section scar ``` EXTRA-ABDOMINAL FIBROMATOSIS: o Outside the abdomen & abdominal wall o Shoulder (20%), chest wall & back (17%), thigh o Genders affected equally o Head & neck more common in children ``` ANSWER: Fibromatosis of the penis is often dorsal – uncommonly ventral

Answer 20

• Peyronie disease causes urethral narrowing - Typically affects the dorsal surface of the penis • Plantar fibromatosis is more common in men (2:1) • Dupuytron contracture (palmer fibromatosis) most commonly affects the ring finger ANSWER: Plantar fibromatosis is not more common in females (male predominance)

Answer 21

``` Pleomorphic sarcoma (formerly malignant fibrous histiocytoma) o Aggressive sarcoma, poor prognosis ``` Epidemiology: - Slight male predilection - Adults, peak age 59 years - Most common type of soft tissue sarcoma - 25-40% of all adult soft tissue sarcoma - Most frequent sarcoma seen secondary to radiotherapy - Can also arise secondary to Paget disease of bone Location: retroperitoneum & proximal extremities Synovial sarcoma: o Intermediate to high grade soft tissue sarcoma - Often has a more indolent course Epidemiology: - Young adults (15-40 years) - Slight male predominace - Second most common soft tissue sarcoma (2.5-10%) - Usually arises in the soft tissues adjacent to large joints (e.g. around the knee in the popliteal fossa) - Arise near joints, however very rare to arise from the joint - Do not arise from synovial structures e.g. joints, tendon sheaths or bursae ANSWER: Pleomorphic sarcoma is the most common soft tissue sarcoma of the extremities. Synovial sarcoma is the second most common.

Answer 22

ANSWER: Angiosarcoma – more likely to be superficial or subcutaneous

Answer 23

* 30% of synovial sarcomas contain calcifications * Tumours larger than 5cm have a poor prognosis * Tumours arise near joints, but very rarely from the joint ANSWER: Synovial sarcoma does not typically arise from the joint

MSK Flashcards

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