Comparison of ultrasonographic findings of schwannomas and angioleiomyomas

Abstract

A subcutaneous tumor accompanied by tenderness has a myriad of differential diagnoses. Indeed, using physical findings alone to achieve a diagnosis is often challenging. In this study, we focused on schwannomas and angioleiomyomas, which usually develop as hard subcutaneous tumors and are often associated with tenderness. We aimed to determine significant differentiating features between the tumor types, using ultrasonography. We compared clinical findings and ultrasonographic imaging and calculated the statistical significance for each item. In total, we analyzed 11 schwannomas and 13 angioleiomyomas of the extremities, trunk and head. There was no significant difference in patient characteristics or clinical findings. Meanwhile, the mean maximum diameter (P = 0.002), localization (P = 0.04) and entering or exiting nerves (P = 0.01) were significantly different according to ultrasonography findings. Thus, ultrasonography provides excellent information for the initial assessment of a slow-growing, painful, subcutaneous soft tissue mass. According to our study, it is difficult to identify a single, differentiating feature between angioleiomyoma and schwannoma on ultrasonography, but including multiple findings during the work-up can facilitate differential diagnosis.

Diagnostic accuracy of multiparametric ultrasound for peripheral nerve schwannoma

“…Peripheral schwannomas are comparatively rare benign tumors, accounting for approximately 5% of all benign soft-tissue tumors (21). One of the problems in differentiating peripheral nerve tumors is that imaging findings of schwannomas, neurofibromas, and other neurogenic tumors are very similar, including the “target sign.” A recent study by Ogata et al (14) (24 patients, 11 schwannomas, and 13 other peripheral tumors) and review by Fujioka (15) both explored the potential of US in differential diagnosis of schwannomas. Authors reported the “target sign” among important but rare findings, consistent with the presence of hypercellular Antoni A areas in the center and myxoid Antoni B areas in the periphery (15).…”

“…The entering/exiting nerves sign was defined as nerve-tumor continuity, indicating the schwannoma genesis of the observed lesion (14) (Fig. 2).…”

Lateral Femoral Cutaneous Nerve Angiomyoma

“…The three main imaging modalities typically employed include ultrasonography, CT, and MRI, each providing less than ideal findings. A study by Ogata et al exemplified the shortcomings of ultrasound’s diagnostic utility demonstrating that no specific differences between a schwannoma and angioleiomyoma were identifiable [ 21 ]. These lesions are detectable on contrasted CT as was the case with our study.…”

Hand Masses

“…On US, they tend to be of homogeneous low echogenicity with increased vascularity on Doppler. 43 On MRI, they are usually isointense or slightly hyperintense to skeletal muscle on T1-weighted images with a heterogeneous appearance on T2-weighted images. 66 There may be areas of internal linear and branching high T2 signal representing bundles of smooth muscle cells surrounding capillary-size vessels.…”

“…42 On US, FTS appears as a well-circumscribed hypoechoic mass closely related to a tendon with internal heterogeneity and increased vascularity on Doppler. 43 On MRI, FTS appears as a well-defined soft tissue mass with nonuniform low signal intensity on T1-and T2-weighted sequences. 44 On fluid-sensitive sequences, the low signal patterns within the lesion are typically stripe-like or irregular, compared with TSGCTs that have a more granular appearance.…”