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Age / Sex : 8 / F
Chief complaint : Pain of left ankle (D: 1month)
What is your impression?
Two weeks later, you can see the final diagnosis with a brief discussion of this case. (Please submit only one answer)
Courtesy : Jin-Gyoon Park, Chonnam National University Hospital
Diagnosis: CRMO ( chronic recurrent multifocal osteomyelitis )
Discussion
Findings:
Ankle AP radiograph
shows a geographic osteolytic lesion of distal metaphysis of left tibia
abutting the growth plate with sclerotic rim. Lateral radiograph shows a
geographic osteolytic lesion of calcaneus abutting the apophyseal growth plate
with sclerotic rim. The lesions of tibia and calcaneus show intermediate signal
intensity on sagittal T1WI, high signal intensity on T2WI, and enhancement on
post contrast T1WI with fat saturation. Perilesional bone marrow and soft
tissue edema is noted.
Differential Diagnosis:
CRMO
Langerhans cell histiocystosis
Infectious osteomyelitis
Diagnosis:
CRMO ( chronic recurrent multifocal osteomyelitis )
Discussion:
Chronic recurrent multifocal osteomyelitis
(CRMO) is a
skeletal disorder of unknown cause, occurring primarily in children and
adolescents that is characterized by
nonbacterial osteomyelitis. Most cases (up to 85%) occur in
females, with a median age of onset of 10 years. . However, it has been described in infants as young as 6
months and in adults as old as 55 years. Some
have regarded CRMO as a pediatric variant of the SAPHO syndrome. Laboratory findings at initial presentation
are essentially nonspecific, with the most common findings being mildly
elevated erythrocyte sedimentation rate and C-reactive protein level with a
normal white blood cell count.
The findings at imaging studies can be suggestive of a diagnosis of CRMO
but are not pathognomonic. Common sites of skeletal involvement include the
long tubular bones and clavicle, but lesions have been described throughout the
skeleton, including the spine, pelvis,
ribs, sternum, scapula, mandible, and hands and feet. Involvement of the
lower extremity has been reported to be three times more common than disease in
the upper extremity. The tibia has been reported as the most common bone
involved. The most common sites of disease are the metaphyses or metaphyseal
equivalents, accounting for approximately 75% of all lesions. In the early stage, plain radiographs
typically demonstrate an osteolytic lesion located adjacent to the growth plate
in the metaphysis. With time, progressive sclerosis is seen around the osteolytic
lesion, so that chronic lesions may be predominantly sclerotic with associated
hyperostosis. The appearance of CRMO lesions can range between purely
osteolytic, osteolytic with a sclerotic rim, mixed lytic and sclerotic, and
purely sclerotic. During the active phase of the disease, MR imaging shows
typical findings of marrow edema, which appears hypointense on T1WI and
hyperintense on T2WI. MR imaging can demonstrate associated periostitis,
soft-tissue inflammation, and transphyseal disease. MR imaging may show small
fluid collections or areas of necrotic bone, However, the presence of a large
fluid collection or abscess, fistulous tract, or sequestrum makes the diagnosis
of infectious osteomyelitis more likely than CRMO. CRMO is more common
in the small bones of the feet than in the hands. It can involve the tarsal
bones such as the calcaneus and talus or the short tubular bones including the
metatarsals and phalanges.
References:
1. Khanna G, Sato TS, Ferguson P. Imaging
of chronic recurrent multifocal osteomyelitis. RadioGraphics 2009; 29:1159–1177
2. Iyer RS,
Thapa MM, Chew FS. Chronic recurrent multifocal osteomyelitis: review. AJR
2011; 196:S87–S91
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