Osteoid Osteoma of the Femoral Neck: Use of the Half-Moon Sign in MRI Diagnosis

Abstract

The half-moon sign is an MRI finding that is highly specific and sensitive for an accurate diagnosis of osteoid osteoma of the femoral neck.

Benign Bone Tumors about the Hip

“…Klontzas et al describe a halfmoon sign of bone marrow edema that can help diagnose osteoid osteomas of the femoral neck. 37 In their study, the half-moon sign of bone marrow edema was significantly associated with the presence of osteoid osteoma (p < 0.0001) with 94.7% specificity and 100% sensitivity for the detection of these lesions. Bone marrow edema in the femoral neck region can represent other pathologic process such as a stress reaction; thus, the patient's clinical history should be correlated with the radiologic findings.…”

Hip and Pelvis Bone Tumors: Can You Make It Simple?

“…However, the nidus may be obscured by reactive marrow edema that may be florid and confusing, in which case it may lead to a delayed diagnosis. 29 CT helps depict the nidus (with a smooth peripherical margin), central mineralization (50%), and a vascular groove sign representing feeding vessels (75%) that confirms the diagnosis. 30 CT is also used to localize and guide the radiofrequency needle used for treating such lesions with radiofrequency ablation.…”

“…10) is considered a rare lesion in the pelvis, it is common in the proximal femur (incidence in this site is almost 20%), seen in young patients (usually 10-25 years). 1,29 This can be subdivided based on location into cortical, cancellous, and subperiosteal.. Cancellous lesions tend to be located in the osseous component of the femur that is within the joint capsule, with potential absence of the characteristic circumferential sclerosis (or sclerosis is seen distant from the tumor, in an extracapsular location), and the nidus is occult. Cancellous osteoid osteoma therefore presents with joint fluid and synovitis, mimicking a monoarthritis (►Fig.…”

Benign Pediatric Tumors and Tumor-Like Conditions of the Hip

“…Klontzas et al described a half-moon sign of bone marrow edema that can be used to help diagnose OOs in the femoral neck. 20 They found a 94.7% specificity and 100% sensitivity for the detection of femoral neck OOs using the half-moon sign. It should be noted that bone marrow edema in the femoral neck region can represent other pathologic process, such as stress reactions, thus the clinical history should be correlated with the radiologic findings.…”