Age / Sex : 16 / M

Age / Sex : 16/male

Chief complaint : left arm swelling

1) What is your impression?

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

* Send Application Answers to In Sook Lee, MD ([email protected])

Courtesy; Hye Won Chung, Asan Medical Center

chronic osteomyelitis

Discussion

Findings:

1)    
Radiograph: osteolytic
lesion with intracortical radiolucency and subtle periosteal reaction

2)    
MRI: cortical
destruction at the diaphysis and associated edema in bone marrow and deltoid
muscle. small bone fragment within the cortical lesion suggesting sequestrum

3)    
CT: sequestrum
and surrounding cortical destruction

Differential Diagnosis:

 Osteoid osteoma, LCH, Ewing’s tumor, Lymphoma

Diagnosis:
 

Chronic
osteomyelitis with sequestrum in humerus

Discussion:

Chronic
osteomyelitis

- Infection
of more than 6 week’s duration

- Chronic
osteomyelitis of long duration with draining sinus tracts may develop squamous
cell carcinoma

Active
chronic osteomyelitis

- Presence
of sequestrum: most specific sign

- Poorly
defined areas of osteolysis

- Osteolysis
in areas of previous sclerosis

- Development
of new, thin, linear periosteal reaction

MR findings
of active chronic osteomyelitis

-Sequestrum

Fragment of dead bone surrounded by granulation tissue

             Low SI on all pulse sequences

No enhancement of the sequestrum itself

High signal lesion surrounding sequestrum

-Intramedullary
abscess cavity

-Cloaca: defect
in the periosteum created by infection showing high signal intensity on T2WI

-Subperiosteal
fluid collection (pus or edema): linear fluid collection elevating the
periosteum and paralleling the cortex

References:

1.    
Helms CA,
Major NM, Anderson MW, Kaplan P, Dussault R. Musculoskeletal MRI, 2nd ed. Philadelphia:
Elsevier Saunders. 2008