Chronic nonbacterial osteomyelitis (CNO) is a pediatric inflammatory disorder similar to chronic recurrent multifocal osteomyelitis (CRMO) but involving only a single bone.
Cause: unknown. It may be related to the SAPHO syndrome.
Age at onset: from infancy to early adulthood
Clinical findings:
(1) development of a single lytic bone lesion
(2) pain and swelling associated with the bone lesion
A single episode may occur, or there may be recurrent episodes, with periodic exacerbations followed by remissions.
The typical imaging pattern is osteolysis with sclerosis.
Laboratory findings:
(1) negative cultures for bacteria and fungi (infection excluded)
(2) histologic examination of a bone biopsy shows acute or subacute inflammation
(3) elevated acute phase reactants during an exacerbation
Differential diagnosis:
(1) bacterial or fungal osteomyelitis
(2) CRMO, which only become apparent after followup for several years
(3) bone tumor
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