Review Question - QID 5489

Adamantinomas (AD) of long bones are rare, low-grade, malignant primary bone tumors with a strong predilection for the mid-shaft of the tibia.

AD is exceedingly rare, accounting for <1% of all malignant primary bone tumors. 75% of cases occur in patients aged in the 2nd through 4th decades. The tibia is affected in 80% to 90% of cases, with synchronous involvement of the ipsilateral fibula in 10 - 50% of people. The four histological patterns have been described for classic adamantinoma—basaloid, spindle, tubular, and squamous—with the basaloid and tubular patterns being the most common.

Bethapudi et al. describe the imaging of adamantinoma. AD is typically located in the tibial diaphysis. The lesions tend to be eccentric, osteolytic, and expansile, which can give the tumor a “soap bubble” appearance.

Most et al. reviewed osteofibrous dysplasia and adamantinoma. They state that chemotherapy and radiation are not effective in the treatment of AD, and surgery is the main treatment option. In addition, they note that these are low-grade, slow growing tumors with very late local recurrence and metastases.

Figure A is an AP radiograph of the left tibia and fibula showing a mildly expansile osteolytic lesion in the midshaft of the tibia with endosteal scalloping and a small amount of focal smooth periostitis laterally. Figure B shows a coronal T1-weighted (left) and sagittal fat-saturated T2-weighted (right) MRI demonstrating low T1, heterogeneous high T2 signal marrow infiltrating neoplasm in the mid-tibial shaft.

Incorrect Answers:
Answer 1: Osteofibrous dysplasia is a rare, benign, fibro-osseous lesion that typically is seen within the cortex of the tibia in children. Lesions are eccentric, intracortical, and osteolytic.
Answer 3: Periosteal osteosarcoma occur on the surface of the bone, most commonly on the femur and tibia and they typically grow in a "sunburst" fashion creating enlarging, linear matrix ossification.
Answer 4: Nonossifying fibromas are the most common benign bone tumors in childhood commonly affecting children 5-15 years old.
Answer 5: Previously referred to as malignant fibrous histiocytoma, undifferentiated pleomorphic sarcoma (UPS) most often presents as a painless, slowly enlarging mass. The histology will often show pleomorphic and bizarre tumor cells with foamy cytoplasm and marked atypia appear on a background of inflamed collagenous stroma.