Msk 5

Question 1

If the physician suspects Hypertrophic Osteoarthropathy (HOA), where should he look next and what should he rule out?

Answer 1

Thoracic cavity

Rule out Bronchogenic carcinomas

Question 1

Answer 1

Leontiasis ossea

Question 2

What are of the body is ALT (lab) indicative of?

Answer 2

Liver

(Look for correlation with ALP - if both are elevated, there may be pathology of the liver)

Question 2

What is the cause of osteonecrosis (aka Avascular Necrosis)?

Answer 2

Compromise of the blood supply to bone

Question 3

“Polyostotic fibrous dysplasia with endocrine dysfunction”

Answer 3

McCune-Albright Syndrome

Question 3

Answer 3

Chalkstick fracture - Paget disease of bone

Question 4

Elderly individual presents complaining that his “hat doesn’t fit anymore.” Bloodwork reveals elevated ALP. Past radiographs reveal bowing of the femur and tibia with chalkstick-type fractures of long bones and extremities. Further analysis reveals osteosarcoma. What’s the diagnosis?

Answer 4

Paget disease of the bone

Question 4

Polyostotic fibrous dysplasia

Answer 4

27% of all cases

earlier age than monostotic

femur, skull, tibia, humerus, ribs, fibula, radius, ulna, mandible, vertebrae

often has craniofascial involvement

crippling deformities (shepherd crook’s deformity & leontiasis ossea) & fractures

Question 6

Why would a disease of overactive bone resorption lead to increased levels (urinary) of hydroxyproline?

Answer 6

Breakdown of collagen located in bone

Question 7

Periosteal new bone growth

Arthritis

Clubbing of the digits

Answer 7

Hypertrophic Osteoarthropathy

Question 8

A histological sample reveals a subchondral infarct (a triangular or wedge-shaped segment of dead tissue) in the head of a femur. What does this indicate?

Answer 8

Osteonecrosis (aka AVN)

Question 9

What labs do we see when diagnosing Paget disease of bone?

Answer 9

Elevated ALP (very high, alkaline phosphatase)

Elevated urinary excretion of hydroxyproline

Normal Ca²⁺

Normal P_i

Question 10

Osteonecrosis, or AVN, in children at the femoral head is also known as

Answer 10

Legg-Calve-Perthes disease

Question 10

Answer 10

Paget disease of bone - Osteosclerotic phase

Question 10

Answer 10

Subchondral infarct - Avascular Necrosis (Osteonecrosis)

Question 11

What is the hallmark lesion of Paget disease of the bone?

Answer 11

Mosaic pattern of lamellar bone, produced by prominent basophilic cement lines 5.12

Question 13

Gross: well-circumscribed intramedullary tan-white and gritty tissue

Microscopic: bone lacks rim of osteoblasts, “chinese character” or “alphabet soup” appearance

Answer 13

Fibrous dysplasia

Question 15

Where is alkaline phosphatase primarily concentrated in the body? Why do we need to know this?

Answer 15

Liver

Bile Duct

Kidney

Bone

Placenta

Elevated ALP may be indicative of pathology in one or more of these areas.

Question 17

Answer 17

Shepherd crook’s deformity - polyostotic fibrous dysplasia WITHOUT endocrine dysfunction

Question 18

What are the abbreviations for Alkaline phosphatase?

Answer 18

ALP

Alk Phos

ALKP

AP

Question 20

Can a monostotic disease evolve into polyostotic form?

Answer 20

No

Question 21

Answer 21

McCune-Albright Syndrome

Question 22

What does this indicate and where should you look next?

Answer 22

Hypertrophic Osteoarthropathy

Look in thoracic cavity for bronchogenic carcinomas

Question 23

Accounts for 70% of all cases

manifests during adolescence

common sites: femur, tibia, ribs, jawbones, clavaria, humerus

frequently asymptomatic, may cause pain, disfigurement

Answer 23

Monostotic fibrous dysplasia

Question 24

Most common clinical presentation is precocious sexual development, often in girls.

Skin pigmentation limited to the same side of the body.

Cutaneous lesions are large macules that are dark to cafe-au-lait with irregular serpiginous borders (“Coasline of Maine”).

Answer 24

McCune-Albright Syndrome

Question 26

What is the cause of Paget disease of the bone?

Answer 26

Unknown

Question 26

A patient with pain due to AVN, or osteonecrosis, would most often locate it to

Answer 26

groin, followed by thigh and buttocks

Question 26

12 year old boy presents with inflammation of the tibial tuberosity and anterior knee pain. The boy is reassured it should resolve on its own in 6 to 18 months. What’s the diagnosis?

Answer 26

Osgood-Schlatter Disease

Question 27

Excesive bone resorption followed by disorganized bone replacement.

Answer 27

Paget disease of bone

Question 28

What’s the cause of HOA?

Answer 28

Unknown

Question 30

What are two common causes of AVN?

Answer 30

Sickle-cell Disease

Corticosteroid administration

Question 31

Benign non-neoplastic replacement of bone (generally medullary cavity of bone) by fibrous tissue. This condition is NOT HEREDITARY.

Answer 31

Fibrous Dysplasia of bone

Question 32

Answer 32

Fibrous dysplasia - no rim of osteoblasts

Question 34

Mechanism of fibrous dysplasia

Answer 34

Gain-of-function somatic mutation during embryogenesis in the GNAS gene, located on chromosome 20.

Leads to hyperactive G proteins

Question 35

Where is Avascular Necrosis (AVN) usually found?

Answer 35

anterolateral femoral head

Question 36

What are the three phases of Paget disease of the bone?

Answer 36

Osteolytic phase - active resorption of bone by osteoclasts

Mixed phase - mixed osteoclastic & osteoblastic phases

Osteosclerotic phase - cement lines seen

5.11

Question 37

What are the 3 distinctive clinical patterns of fibrous dysplasia?

Answer 37

Monostotic - single bone involvement

Polyostotic - multiple bone involvement

Polyostotic disease associated with cafe-au-lait pigmentations and endocrine abnormalities, especially precocious puberty