MR imaging assessment of juxta cortical edema in osteoid osteoma in 28 patients

Abstract

Osteoid osteoma (OO) is a benign skeletal neoplasm. Twenty-eight patients with proven OO were studied with MRI regarding soft tissue involvement which was diagnosed when high proton-density and T2-weighted signal intensity and low signal intensity on T1-weighted images were found close to bone. Most tumors were located in the femur and tibia; 6 cases diaphyseal, 12 metaphyso-diaphyseal, and 10 epiphyseal. In relation to the cortex, 15 were located centrally or in its outer margin. Soft tissue involvement was found in 15 patients (53.6 %). A statistical relationship was found between soft tissue involvement and the tumor's location with regard to the cortex, being more frequent in peripherally located tumors. Therefore, soft tissue involvement is a frequent finding in peripherally located OO.

Magnetic resonance imaging findings of osteoid osteoma of the proximal femur

“…This is a less known finding in OO and could consequently be mistakenly regarded as a sign of malignancy or infection [12,14,33].…”

“…Soft tissue involvement appears as a juxtacortical edematous tissue adjacent to the OO nidus [12,14,33]. This is a less known finding in OO and could consequently be mistakenly regarded as a sign of malignancy or infection [12,14,33].…”

“…Moreover, these cases are usually studied with low spatial resolution sequences, which are less accurate than CT in the demonstration of OO nidus. Early experience with MR imaging has shown that in cases in which nidus is not identified, the presence of secondary marrow edema, joint effusion and soft tissue mass can lead to erroneous diagnosis of aggressive disease [8,9,[12][13][14]. Therefore, it is extremely important to look carefully for the nidus on MR images in young patients with these findings.…”

“…If OO is not detected, other causes of bone marrow edema such as infection, malignant neoplasm, transient osteoporosis, reflex symphatetic dystrophy and regional migratory osteoporosis can be erroneously diagnosed [8,9,[12][13][14]. Relationships of transient osteoporosis, reflex symphatetic dystrophy and regional migratory osteoporosis remain controversial [7,32].…”

“…Prostaglandin-induced peritumoral abnormalities associated with OO of the femoral neck and trochanters are: (1) synovitis of the hip joint, (2) bone marrow edema and (3) juxtacortical soft tissue edema. MR imaging is the most sensitive diagnostic tool in detecting peritumoral soft tissue abnormalities induced by prostaglandins [8,9,[12][13][14]29].…”