(2) Osteoma, Enostoma, Osteoid Osteoma, Osteoblastoma

Question 1

What are osteomas comprised of?

Answer 1

dense cortical bone
(arise from surface of bone)

Question 2

What is the preferential location of osteomas?

Answer 2

above C1
- skull
- mandible
- sinuses (frontal, maxillary, ethmoid, sphenoid, mastoid)

Question 3

What is a potential complication of an osteoma?

Answer 3

sinusitis if formed in sinus
causes sinus/facial/head pain & pressure due to obstruction

Question 4

What is the clinical presentation of an osteoma?

Answer 4

most are asymptomatic

Question 5

What are the radiographic features of an osteoma?

Answer 5

• usually solitary
• densely blastic mass (sclerotic)
• well-defined borders

Question 6

What are enostomas comprised of?

Answer 6

woven bone

Question 7

What is the preferential location of enostomas?

Answer 7

non-skull:
- medullary cavity
- epiphyseal, metaphyseal
- long bone surfaces

Question 8

Enostomas are also called ____ OR ____ of bone

Answer 8

• bone island
• hamartoma

Question 9

What does “hamartoma” mean?

Answer 9

abnormal/disorganized growth comprised of the same tissue (normal tissue) from which it grows

Question 10

How would you differentiate an enostoma from blastic metastasis?

Answer 10

Mets:
- ^ESR
- bone scan shows “hot” areas of blastic activity
- plural
- older age
Enostoma:
- solitary
- younger age

Question 11

How does an enostoma appear on a bone scan and why?

Answer 11

appears normal because enostoma is comprised of normal tissue, just disorganized (no increase in blastic activity)
(occasionally warm on bone scan)

Question 12

Bone islands are comprised of ____ bone, located in ____ space

Answer 12

• woven
• trabecular

Question 13

What age group is primarily affected by bone islands?

Answer 13

any age
Adults > children

Question 14

What is the clinical presentation of an enostoma?

Answer 14

asymptomatic

Question 15

What are the radiographic features of an enostoma?

Answer 15

• usually solitary, radiopaque
• round/oval, long axis aligned w/ wt-bearing trabeculae (stress lines)
• bone island >2cm

Question 16

What CT finding is associated with an enostoma?

Answer 16

radiating (brush) border

Question 17

If you see a bone island in an older patient, what must be ruled out first? What additional follow-up is needed?

Answer 17

blastic mets
need labs & bone scan

Question 18

The center of an osteoid osteoma is called a ____

Answer 18

nidus

Question 19

What age group is primarily affected by osteoid osteomas?

Answer 19

10-25 yrs
(most in teens)

Question 20

What bones are capable of forming an osteoid osteoma?

Answer 20

any bone that formed via endochondral ossification

Question 21

What is the preferential location of osteoid osteoma?

Answer 21

• femur or tibia (50%)
  (10% in neural arch of spine)
• cortically based
• metaphyseal & diaphyseal

Question 22

How large is a typical nidus?

Answer 22

<1 cm

Question 23

How does an osteoid osteoma appear radiographically?

Answer 23

• radiolucent lesion (nidus)
• surrounding sclerosis

Question 24

What type of periosteal reaction is seen in an osteoid osteoma?

Answer 24

solid (surrounding sclerosis)

Question 25

What part of a nidus may be ossified?

Answer 25

trabeculae in center (more mature)

Question 26

How would a patient with an osteoid osteoma present clinically?

Answer 26

- adolescent w/ insidious onset - pain at night (fewer distractions; can behave similar to fatigue Fx in adolescents) - pain relieved by aspirin (not by Advil/Tylenol)

Question 27

What type of periosteal reaction would occur in a fatigue fracture?

Answer 27

solid

Question 28

How might you differentiate a fatigue fracture from osteoid osteoma if unsure about an x-ray?

Answer 28

CT scan -> gives good bony definition, can see nidus clearly through periosteal Rxn

Question 29

How is an osteoid osteoma treated?

Answer 29

removal of nidus via En Bloc excision

Question 30

How would an osteoid osteoma appear on CT?

Answer 30

central calcific fleck

Question 31

How would an osteoid osteoma appear on a bone scan?

Answer 31

positive: double density sign

Question 32

What is on your list of differential diagnoses for an adolescent with insidious onset of pain?

Answer 32

- fatigue Fx - osteoid osteoma - osteoblastoma - Brodie abscess

Question 33

What is the number 1 cause of a solid periosteal reaction?

Answer 33

fatigue Fx

Question 34

What is the clinical presentation of an osteoid osteoma in the spine?

Answer 34

painful scoliosis

Question 35

What side of scoliosis would an osteoid osteoma be found on?

Answer 35

concave side (bend toward side of pain)

Question 36

What are the radiographic features of an osteoid osteoma in the spine?

Answer 36

densely blastic: - pedicle - lamina - facet

Question 37

What age group is primarily affected by osteoblastoma?

Answer 37

<20 yrs

Question 38

What is an osteoblastoma comprised of?

Answer 38

(similar to osteoid osteoma) osteoblasts lay down osteoid

Question 39

What is the preferential location of osteoblastoma?

Answer 39

- spine: SP, TP, laminae (post. elements) - C4, C5, C6 common - TL - metaphysis, diaphysis of long bones (LE MC, dorsal surface of talus)

Question 40

How large is a typical osteoblastoma in the extremities?

Answer 40

>2cm diameter (progressive enlargement)

Question 41

How does osteoblastoma in the spine appear radiographically?

Answer 41

- radiolucent lesion (geo. lytic) **without** sclerotic reaction - expansile lesion of neural arch (4-6cm) - thin cortex

Question 42

What are the differential diagnoses for osteoblastoma in the spine?

Answer 42

(Alphabet soup) ABC GCT

Question 43

What pattern of destruction is seen in osteoblastoma?

Answer 43

geographic lytic

Question 44

What type of periosteal reaction is seen in an osteoblastoma?

Answer 44

none

Question 45

How does osteoblastoma in the extremities appear radiographically?

Answer 45

- lytic & expansile - radiolucent nidus (>2cm) **limited sclerosis** - sparing of epiphysis

Question 46

What are the differential diagnoses for osteoblastoma in the extremities?

Answer 46

Osteoid osteoma ABC Brodie abscess

Question 47

What is the clinical presentation of an osteoblastoma?

Answer 47

- insidious onset - pain unresponsive to aspirin (takes much larger dose due to ^size of lesion) and not nocturnal - swelling, palpable mass - TS or LS lesion present w/ painful scoliosis (>50%) - possible spinal stenosis

Question 48

How is an osteoblastoma treated?

Answer 48

(similar to osteoid osteoma) - wide/en bloc excision via curette (not preferred) - radiofrequency ablation -> electric probe inserted to liquify tumor ("microwaves" tumor)

Question 49

If an osteoma is symptomatic, what is the most likely symptom? A) "my hat doesn't fit anymore" B) visual disturbance C) sinusitis D) headaches

Answer 49

C

Question 50

What is the most likely diagnosis?

Answer 50

Osteoid osteoma

Question 51

What is the most likely diagnosis?

Answer 51

Enostoma (bone island)

Question 52

What is the diagnosis?

Answer 52

Osteoma

Question 53

What is the diagnosis? What bone is involved?

Answer 53

Osteoma of the mandible

Question 54

What symptoms might this patient present with?

Answer 54

(Osteoma in frontal sinus) Sinusitis

Question 55

What is the diagnosis?

Answer 55

Osteoid osteoma

Question 56

What is the diagnosis?

Answer 56

Osteoid osteoma

Question 57

What is the diagnosis?

Answer 57

Osteoid osteoma

Question 58

45 year old male. Give 2 differentials.

Answer 58

(Multiple blastic foci) 1. Blastic Mets 2. Bone island (enostoma)

Question 59

What type of periosteal reaction is demonstrated? Give 2 differential diagnoses for this lesion.

Answer 59

Solid 1. Fatigue Fx 2. Osteoid osteoma

Question 60

What would this lesion look like on a bone scan?

Answer 60

Double density sign

Question 61

What is the diagnosis if the pathology report comes back identical to an Osteoid osteoma?

Answer 61

Osteoblastoma (>2cm) (Non-aggressive in post. spine = alphabet soup DDx)