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Tumor Discovery CRMO presenting as multifocal bone LCH

fever, night sweats, and weight loss were observed in 17% Since imaging findings are diagnostic in CRMO, a
of children. Only one of our patients (33%) had systemic biopsy is recommended only in unclear conditions. In the
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symptoms. The absence of weight loss and debility despite study from Bristol, 24 out of the 41 patients underwent
extensive bone involvement might suggest a diagnosis of biopsy for confirmation. The majority had inflammatory
CRMO. cell infiltrate with reactive bone changes, mainly fibrosis.

The largest pediatric case series is from Bristol Royal Half of the slides examined had a predominant plasma
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Hospital for Children in the United Kingdom, comprising cell infiltrate. All our children exhibited a chronic
41 diagnosed cases over 8 years. A female preponderance inflammatory exudate with lymphocytes, plasma cells, and
of 3:1 was observed, with a mean age of 9 (1 – 17) years. reactive histiocytes.
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Our cohort consisted of three children, of which two were As there are no universally accepted diagnostic criteria
boys, with a mean age of 11 (10 – 12) years. CRMO/CNO for CRMO, it remains, until now, a diagnosis of exclusion.
is usually not detected in children under 2 years old, and The Bristol group has proposed diagnostic criteria for
other differential diagnoses should be considered. CRMO, as shown in Table 1, but these criteria have not
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In the study by Roderick et al., the most frequent been validated in children. In atypical presentations,
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differential diagnoses were infective osteomyelitis, tissue diagnosis in the form of biopsy from the bone
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malignancy, Ewing’s sarcoma, LCH, non-specific lesions clinches the diagnosis. Roderick et al. suggest that
musculoskeletal disorders, and juvenile idiopathic arthritis. atypical sites of involvement and the presence of systemic
All our children were referred with a primary diagnosis of manifestations warrant a biopsy, especially in communities
LCH. with a high prevalence of tuberculous osteomyelitis. All
our patients underwent a biopsy to establish a diagnosis
Clinical presentation can vary from mild or due to atypical presentations.
asymptomatic single-bone involvement, which is more Treatment of CRMO is largely extrapolated from
common, to multifocal recurrent severe osteomyelitis. schedules used in juvenile idiopathic arthritis and case
CRMO mainly involves the metaphysis of the bones of reports published in the literature. Drugs used are
the extremity, vertebrae, pelvis, or clavicle, though any NSAIDs, corticosteroids, and DMARDs. Some case
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bone can be involved. Skin involvement in the form of reports have shown responses to anti-TNF agents and
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psoriasis or palmoplantar pustulosis and inflammatory bisphosphonates. Many retrospective studies have shown
bowel disease has also been associated with this condition, the effectiveness of NSAIDS and steroids, but the period
especially in adult patients. In the study from Bristol, the of remission achieved is usually short-lived. Pamidronate
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most common bone involved was the tibia, followed by has been shown to be effective in certain studies with
the clavicle. Symmetrical bone involvement was observed long periods of remission. Similar to autoimmune bone
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only in 12% of children. Among our three patients, two diseases, TNF inhibitors have also been investigated in the
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had extensive bone involvement with spine and pelvic
bone lesions, which exhibited lytic and sclerotic changes;
the third child had disease mainly limited to the upper Table 1. Bristol diagnostic criteria for chronic recurrent
extremity. multifocal osteomyelitis
Whole-body MRI with T2-weighted sequences The presence of typical clinical findings (bone pain with or without
(Turbo Inversion Recovery Measurement [TIRM]) and/ localized swelling without significant local or systemic features of
or gadolinium-enhanced T1 sequences with fat saturation inflammation or infection)
is the imaging modality of choice in inflammatory bone AND
diseases. In CRMO, MRI can detect edema of the bones The presence of typical radiological findings (plain X-ray [showing
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before the appearance of lytic and sclerotic bone disease. a combination of lytic areas, sclerosis, and new bone formation] or
preferably STIR MRI [showing bone marrow edema ± bone expansion,
It can also help in assessing the response to treatment at lytic areas, and periosteal reaction])
follow-up. In our series, all our children had lytic and AND EITHER
sclerotic changes in the imaging. Since all our children were
referred with a diagnosis of LCH, all of them underwent Criterion 1: More than one bone (or clavicle alone) without
significantly raised CRP (CRP <30 g/L).
PET-CT at our center. The low-grade FDG uptake ranging
from an SUVmax of 2 – 3 was observed in all children, Criterion 2: If unifocal disease (other than clavicle), or CRP
>30 g/L, with bone biopsy showing inflammatory changes (plasma
with all children demonstrating lytic and sclerotic areas cells, osteoclasts, fibrosis, or sclerosis) with no bacterial growth whilst
in the corresponding CT images. The presence of lytic not on antibiotic therapy
and sclerotic lesions in the CT scan with the low PET-CT Abbreviations: CRP: C-reactive protein; MRI: Magnetic resonance
uptake might give us a high index of suspicion of CRMO. imaging; STIR: Short tau or short TI inversion recovery.

Volume 3 Issue 3 (2024) 4 doi: 10.36922/td.3102