Clinical significance of magnetic resonance imaging in the preoperative differential diagnosis of calcifying aponeurotic fibroma

Background. Although the clinical and histological features of calcifying aponeurotic fibroma are well described, the magnetic resonance imaging (MRI) findings have been reported for only five cases. The purpose of this study was to describe a series of MRI findings in this rare entity to assess its utility in preoperative and differential diagnosis. Methods. MRI findings together with the clinical signs and radiographs of six patients with pathologically proven calcifying aponeurotic fibroma were retrospectively reviewed. Distribution, morphology, margins, edematous changes, and relation to the surrounding structures together with signal intensity of each sequence of MRI were evaluated. Results. MRI demonstrated subcutaneous distribution, ill-defined appearance, and a tendency to infiltrate into or adhere to the surrounding tissues. The masses were of isointensity to low intensity on T1-weighted images. T2-weighted images showed heterogeneous high signal intensity with minor areas of isointensity to low signal intensity. Postcontrast T1-weighted images demonstrated heterogeneous intense enhancement. Conclusions. MRI revealed several features that can contribute to the preoperative differential diagnosis of calcifying aponeurotic fibroma from other fibrous tumors, giant cell tumor of the tendon sheath, or soft tissue sarcoma. As a result, MRI would help orthopedic oncologists plan the surgery for this rare entity.