Chronic recurrent multifocal osteomyelitis beginning with a solitary lesion of the ilium

BACKGROUND: Chronic recurrent multifocal osteomyelitis (CRMO) is an idiopathic inflammatory disease. The initial lesions are typically found in the metaphyses, generally without periosteal reaction. CASE PRESENTATION: We present a case of a 14-year-old female teenager with relapsing and remitting right iliac pain. There was no evidence of infectious organisms, neoplastic processes, or hematologic malignancy based on laboratory tests. Initial computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated atypical periosteal proliferation in the right ilium. Histopathology demonstrated only non-specific chronic inflammation compatible with CRMO. Two years later, this patient developed left humeral pain. MRI and CT images revealed thickening and marrow edema involving the humeral cortex. CONCLUSIONS: This case highlights that CRMO can begin as a unifocal lesion and also possibly within the ilium, despite usually being multifocal and involving the long bone metaphysis.