Bone lesions and infections - MSK

Question 1

Multiple Myeloma (marrrow)

Answer 1

• Most common (20 million /yr), 50-70 yo, any bone – classic xray is in skull
• Typical lytic “punched out” lesions of multiple myeloma

Question 2

Osteosarcoma

Answer 2

Teens, (2-3 cases per million people per yr), around knee, also hip and shoulder

Question 3

Ewings Sarcoma

Answer 3

• 5-20 yo, LE, pelvis, upper arm, ribs
• Large, expansile lytic lesion of distal femoral metaphysis w/wide zone of transition and cortical destruction and associated soft tissue mass
• TX: Chemo + surgery, radiation or both, limb salvage (artificial joints and bone), used to do amputation

Question 4

Chondrosarcoma

Answer 4

40-70 yo, hip/pelvis, should

Question 5

Osteoid Osteoma

Answer 5

• Benign bone lesion
• Small, makes bone
• Night pain (keeps them awake) relieved by aspirin
• Ages 10-20
• Tibia/femur
• Surgery or heat ablation

Question 6

Enchondroma

Answer 6

• Cartilage lesion
• Asymptomatic unless fx
• Any age
• Most common hand tumor
• Conservative mgmt
• Benign bone lesion

Question 7

Fibrous Cortical Defect (smaller lesion) /Non-ossifying fibroma (big/larger)

Answer 7

• Benign bone lesion
• Most common benign bone tumor in kids
• Shafts of long bones
• Disappear after adolescence
• Usually asymptomatic
• Follow w/ x-rays

Question 8

Unicameral Bone Cyst

Answer 8

• Primarily children
• Cause unknown, perhaps growth plate/circulation abnormality
• Proximal humerus/femur
• May fracture
• Treatment with aspiration and steroid or matrix injection
• Benign bone lesion

Question 9

Aneurysmal Bone Cyst

Answer 9

• Long bones and spine
• Usually < 20 yo
• Swelling and pain
• Vague injury hx
• Currettage/graft/resection
• 30% recurrence
• Benign bone lesion

Question 10

Osteomyelitis

Answer 10

• Children – hematogenous (Originating in or spread by the blood), highly vascular metaphysis
• Adults - trauma (open fx or post op)
• Presentation: Fever, pain, swelling, drainage if open fx
• CBC, ESR, CRP, CT or MRI
• Aspiration or biopsy – definitive dx
• Organisms: Kids - S. aureus, gr A strep, Adults - S. aureus, Pseudomonas (stepping on nail)
• Treatment: Difficult, Long course parenteral or local abx, Surgical debridement

Question 11

Septic Arthritis

Answer 11

• Direct inoculation, hematogenous spread, extension from osteomyelitis
• S. aureus, Pseudomonas (IV drug use), TB & fungal (immigrant), N. gonorrhea (sexually active)
• Joint pain (knee pain often means something wrong with hip), limited ROM, redness and warmth
• Fever, tachycardia, decreased appetite possible
• Immune compromized pts don’t mount good inflammatory response!
• Can have infected joint without a typical presentation (not super hot/swelling/inflammatory response)
• CBC, ESR, CRP
• Joint fluid aspiration for crystals, gram stain, culture, cell count – r/o gout or pseudogout
• Joint fluid WBC > 50,000/mm3, low glucose, high protein
• Blood culture, lyme titer as indicated
• X-rays
• Immediate empiric IV Abx – want to cover staph auerus etc
• Surgical joint lavage
• Always refer to orthopedics if worried about septic arthritis
• Abscess in joint that will destroy joint and tissues