Value of ultrasonography in neurilemmoma diagnosis: the role of round shape morphology.

OBJECTIVE To evaluate the contribution of ultrasonography in the diagnosis of neurilemmoma and to establish if a round or round-like shape adds useful information for ultrasonographic diagnosis. METHODS Archives of ultrasound findings in 203 patients (127 males and 76 females, aged 14 -72 years old, mean 32.1 +/- 25.8) with limb mass were reviewed. The maximal and minimal diameter of the lesions was 78 mm and 11 mm, respectively (mean 34.7 +/- 15.6 mm). Lesions' morphology, size, capsule, and relationship with the adjacent nerve were analyzed, round-like or round shaped was focused, ratio of longitudinal maximal diameter and short maximal diameter (L/S) was calculated. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ultrasonographic diagnosis were determined. RESULTS In 37 patients with ultrasonographic suspicion of neurilemmomas, the neurilemmomas were confirmed in 31 cases. From 166 patients with tumors presumed as being non-neurilemmoma lesions, 18 cases in the final diagnosis were neurilemmomas. Ultrasound had 63.3% sensitivity, 86.0% specificity, 56.4% positive predictive value, 89.2% negative predictive value, and 80.9% accuracy for the diagnosis of neurilemmoma. Round-like or round shaped and L/S diameters ratio were not specific for neurilemmomas ultrasonographic appearance (P > 0.05). CONCLUSION Ultrasound can diagnose neurilemmomas with high accuracy, but the round or round-like shaped and L/S diameters ratio have little value in ultrasonographic identification of neurilemmomas of the limbs.