Age / Sex : 34 / F

Chief complaint: right shoulder pain for several months

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 최윤선(Yun Sun Choi), 을지대을지병원(Eulji Hospital, Eulji University)

Brodie’s abscess

Discussion

Findings:

Radiograph shows a well-defined
radiolucent lesion with sclerotic border in the metaphysis of the proximal
humerus. MR images show a serpentine cavity which has inner rim of high signal
intensity on T1-weighted MR image and outer rim of low signal intensity on all
sequences corresponding to reactive sclerosis in the lower portion of the
lesion. Finally, associated bone marrow edema is also present. T1-weighted MR
images obtained after intravenous gadolinium administration show a central
non-enhancing fluid-like component with peripheral enhancement, a tract
penetrating the cortex anteriorly, and soft tissue spread.

Differential Diagnosis:

1. classic metaphyseal central
location - little difficulty in diagnosis

2. metaphyseal eccentric location -
nonossifying fibroma, CMF

3. epiphyseal location -
chondroblastoma, clear cell sarcoma, intraosseous ganglion, aneurysmal bone
cyst

4. diaphyseal location - Langerhans
cell histiocytosis, Ewing’s sarcoma, osteosarcoma, lymphoma 

5. intracortical location - osteoid
osteoma, stress fracture, hemangioma

Diagnosis: Brodie’s abscess (chronic
osteomyelitis)

Discussion:

Brodie’s
abscess is a localized form of subacute or chronic osteomyelitis, which may
persist for years without any symptom and with normal laboratory parameters. It
may mimic various benign and malignant conditions, and frequently be confused
with bone tumors. The most causative organism is Staphylococcus aureus.
On radiograph, the abscess appears as a circumscribed radiolucent lesion with
surrounding sclerosis showing predilection for the metaphysis of tubular bones,
particularly the tibia. It may be tethered to the growth plate, and the cavity
progressively elongates, with extending to the epiphysis. An area of sclerosis
may be seen centrally in the lucent lesion, compatible with a sequestrum. MRI
is the most sensitive modality to evaluate a Brodie’s
abscess. A characteristic but no a pathognomonic finding on MRI that helps to
exclude the presence of a bone tumor is “Penumbra sign”. The
penumbra sign has been reported as being a hyperintense feature of the thin
layer of highly vascularized granulation tissue which lines the abscess cavity
on T1-weighted MR image. A gadolinium enhanced image depicts a central
non-enhancing defect surrounded by enhancing rim. However, the defect can
enhance if the abscess cavity is filled with granulation tissue rather than
pus. As a complication, Brodie’s abscess may progress to
intraosseous tunneling and lead to pus drainage.

References:

1. Kornaat PR, Camerlinck
M, Vanhoenacker FM, De Praeter G, Kroon HM. Brodie's abscess revisited. JBR-BTR
2010;93(2):81-86

2. Marui T, Yamamoto T,
Akisue T, Nakatani T, Hitora T, Nagira
K, et al. Subacute osteomyelitis of long bones: diagnostic usefulness of
the ”penumbra sign” on MRI. J Clin Imaging 2002;26: 314 -318

3. Contreras MA, Andreu JL, Mulero J, Gonzalez
C. Brodie’s abscess with a fistulous tract connecting with the joint space.
Arthritis Rheum 2000;43:2848–2850