Osteoid osteoma is a benign bone tumor most common in young patients, typically causing pain worsened at night. Radiographs show a small lucent nidus surrounded by reactive sclerosis. CT precisely defines the calcified nidus. MRI demonstrates surrounding bone marrow edema. Treatment involves surgical excision or thermocoagulation of the nidus, providing effective pain relief. A multimodality imaging approach is useful to characterize the lesion and differentiate it from other causes of bone pain.

1. OSTEOID OSTEOMA
19 Yr old male with
pain in in the dorsal
aspect of the medial
aspect of left mid
foot . o/e there is
pain over the FREE LANCE RADIOLOGY
mentioned part of the Basic approach for
left mid foot . continuation of
Diagnostic Radiology
education

2. General considerations/ Incidence /Clinical features
• :
• First described by Henry jaffe ( 1925). Not accepted for several
decades and was considered as variant of osteomyelitis .
• 2.6% of all excised bone tumors and 11 % of all benign bone
tumors .
• Young patients ( 10 to 25 years) . youngest patient reported
was 8 month old patient with lesion in tibia . Male : female
ratio is 2:1 .
• Clinical profile :
• Pain +_ vasomotor disturbance ( profuse sweating / increased
skin temperature) . Classical description is of gradual onset of
increasingly deep / severe / aching pain ( 65% will have night
pain relieved by aspirin) . CAN BE CONFUSED WITH : septic
arthritis , inflammatory , rheumatoid arthritis so patient may
end up with rheumatology opinion.

3. General considerations /Incidence
/Clinical features
• Localized swelling ,point tenderness , limitation of the
motion, painful limp, stiffness , weakness of nearby
joint , muscle atrophy may be noted. Painful scoliosis
(lesion located in the concave side of the curve in
thoracic / lumbar spine) . In cervical spine : torticollis /
secondary contracture of the sternocleidomastoid
muscle may be noted .Lesion in the spinous processs
lead to localized pain and spinal stiffness .
• 50% occur in proximal femur / tibia ( predilection for
upper end of the femur , particularly the neck /
trochanteric region) .In spine : most of the lesions are
in neural arch .

4. Pathological features /Radiologic features/Differential
diagnosis /Treatment and prognosis:
• Lesion : Nidus ( reddish brown vascularised tumor <= 10mm) .
Significant reactive sclerosis with cortical thickening / solid periosteal
reaction encasing the nidus . Nidus is initially uncalcified and with
maturity speck of calcification is seen in it . Bone expansion may be
noted at the lesion site .
• Three anatomic locations of the osteoid osteoma :
Cortical ( most common)
, Cancellous (
intramedullary )
Subperiosteal . Histological and radiological appearance varies .
• Well developed lesion has lucent nidus with surrounding florid perifocal
reactive sclerosis/appositional periosteal new bone formation ( typical
of cortically placed osteoid osteoma ).The sclerosis is maximally seen
caudal to the nidus . Nidus size is, <=1cm in diameter . Single
roengenographic view may not be sufficient to demonstrate the nidus
. central fleck of calcification is seen in the nidus with maturity .
• Intramedullary lesion that are intracapsular provoke much less reactive
sclerosis because of low rate of bone production from intracapsular

5. Pathological features /Radiologic features/Differential
diagnosis /Treatment and prognosis:
• Spinal osteoma’s are elusive lesions . lumbosacral strain
, psychogenic back pain , cervical strain , herniated nucleus
pulposus , biomechanical back pain are frequent prior
diagnosis .Most spinal lesions are seen in the neural arch .
Reactive sclerosis may give appearance of dense ivory pedicle
or lamina . This appearance must be differentiated from
stress response opposite a unilateral spondylosis,congenital
agenesis of the contralateral pedicle , osteoblastoma
, osteoblastic metastatic carcinoma .
• Angiography shows vascular blush in the arterial phase persisting late into
the venous phase. This definitely differentiates the osteoid osteoma from
brodies abscess which shows no such vascular blush in it’s necrotic cavity .
On bone scan there is regional increase in the uptake ( double density
sign)

6. D/D AND TREATMENT
• D/D :
– Garre’s chronic sclerosing osteomyelitis : This entity has
been disregarded as singular / distinct disease process.
– Brodies abscess : Lucent nidus in brodies abscess is >1cm
often close to 2 cm ).Halo rim of sclerosis surrounding the
nidus is more thick / irregular . Vascular blush seen in the
angiographic phase in the osteoidosteoma is absent in the
necrotic core of the osteoid osteoma . Note :Night pain
relieved by aspirin is seen in brodies abscess and osteoid
osteoma .
– Stress fracture : lesion may mimic osteoid osteoma .
Sequential studies over time and images usually
demonstrate the healing of the fracture .

7. D/D AND TREATMENT
• T/T :
1. Natural history of the disease is self limiting .
2. Radiotherapy / thermocoagulation
3. Wide enbloc excision of the nidus and
sclerotic bone. (surgery may be delayed
unless nidus of adequate size is seen) .
4. Recurrence is rare.

8. CONVENTIONAL RADIOGRAPHS
SITE OF PAIN
Single view may not be sufficient to
demonstrate the roentgen findings of
osteoid osteoma so multiple views may be
needed .

9. MR imaging : Good to demonstrate
marrow edema
Dorsal aspect of the medial
cuneiform has focal subcentimetre
SIZED MR signal change in the
subcortical location. Appreciate
significant ill defined marrow edema
TIW T2W STIR

10. LONG AXIS CORONAL IMAGES
STIR IMAGE : MRROW EDEMA IN THE
MEDIAL CUNIFORM AND ADJACENT SOFT
TISSUE

11. LONG AXIS SAGITTAL AND SHORT AXIS
AXIAL IMAGE
STIR IMAGE

12. SAGITTAL MR IMAGES
TIW SEQUENCE STIR SEQUENCE

13. PLAIN CT IMAGE AND
CORROBORATIVE MR IMAGE
( SPGR SEQUENCE)
PLAIN CT SHOWS DENSE NIDUS SPGR SEQUENCE OF MR defines
( MATURE CALCIFIED ) . <10mm . the nidus in cortical location of
Cortical location with sclerosis medial cuneiform
around it

14. CARRY HOME MESSAGE
1. HISTORY ( pain worse at night )
2. CLINICAL EXAMINATION
3. CONVENTIONAL RADIOGRAPH
( multiple views)
4. CT ( for nidus)
5. MRI ( for marrow edema)
6. ANGIOGRAM ( to differentiate from brodies
abscess)
All these modalities play important role to
define the fetaures of osteoid osteoma