Differentiation Between Schwannomas and Neurofibromas in the Extremities and Superficial Body

Abstract

Abbreviations CDUS, color Doppler ultrasonography; MRI, magnetic resonance imaging; PSV, peak systolic velocity; RI, resistive index enign peripheral nerve sheath tumors are divided into 2 major groups: schwannomas (neurilemomas) and neurofibromas.1 Differentiation of schwannomas from neurofibromas is of relevance to surgeons because schwannomas can be easily shelled out while preserving nerve contiguity. In most neurofibromas, however, the nerve is incorporated within the mass, and the required surgery includes resection and subsequent nerve grafting to preserve and restore function. B ArticleArticle includes CME test CME CME Objective. The purpose of this study was to verify whether high-resolution and color Doppler ultrasonography could distinguish schwannomas from neurofibromas. Methods. Seventy-six tumors in 71 patients were included in this study. There were 46 patients (50 tumors) with schwannomas and 25 patients (26 tumors) with nondiffuse neurofibromas in the extremities or superficial parts of the body. Ultrasonographic examinations were performed in all patients. The tumor size, shape, location, internal echogenicity, posterior acoustic phenomenon (eg, shadowing or enhancement), capsule, relationship with the adjacent nerve, and presence of cystic components were documented. Color Doppler studies (75 lesions) and spectral Doppler studies (44 lesions) were performed. All data were analyzed with statistical software to check the significance. Results. Both tumors presented as well-defined hypoechoic nodules on ultrasonography. They were oval or lobulated, showed posterior acoustic enhancement, and were hypervascular on color Doppler ultrasonography. There was no significant difference with respect to ultrasonographic morphologic characteristics. The rates of centric, eccentric, and undetermined associations with nerves were 40%, 20%, and 40% in the schwannomas and 46.2%, 0%, and 53.8% in the neurofibromas, respectively, showing a significant difference (P = .032). There was no significant difference in the chance of cystic changes between the schwannomas (30%) and neurofibromas (23%). Conclusions. No ultrasonographic finding (gray scale, color Doppler, or spectral analysis) allows differentiation between neurofibromas and schwannomas of the extremities. A nerve eccentrically entering a mass was seen only in schwannomas, and that may allow differentiation between neurofibromas and schwannomas.

High-resolution ultrasonography and diffusion tensor tractography map normal nerve fascicles in relation to schwannoma tissue prior to resection

“…10,11,14 Typically, it has been challenging to distinguish between peripheral NST types using ultrasound alone. 1 However, the position of the tumor relative to the nerve may provide supportive evidence.…”

Sural nerve schwannoma: a case report

“…It is difficult to diagnose the type of benign peripheral nerve sheath tumor from ultrasonography alone and especially if the status of the origin nerve cannot be commented on. 8,9 The closest differential to a BPNST on USG is a ganglion cyst. 9 Differentiation of schwannomas from neurofibromas is of a great surgical importance because schwannomas can be easily shelled out while preserving nerve contiguity in contrast to neurofibromas where the nerve is incorporated within the mass, and the required surgery includes resection and subsequent nerve grafting to preserve and restore function.…”

“…8,9 The closest differential to a BPNST on USG is a ganglion cyst. 9 Differentiation of schwannomas from neurofibromas is of a great surgical importance because schwannomas can be easily shelled out while preserving nerve contiguity in contrast to neurofibromas where the nerve is incorporated within the mass, and the required surgery includes resection and subsequent nerve grafting to preserve and restore function. As being situated in lower third of leg, swelling of a size approximately 6 x 4 cm is considerable as a large size & there being a very little room for space expansion, any mass along the nerve without any neurological symptoms is a very uncommon finding.…”

Methodology and indications for high-resolution sonography (HRUS) of the nerves

“…As the tumor grows larger and older, it becomes more vascularized and retroactive changes in the tumor matrix, such as cysts or areas with heightened or nonuniform echogenicity, appear [24]. An ultrasound does not allow to completely differentiate between different types of tumors [27]. Despite that, diagnosing the tumor proves valuable, as nerve sheath tumors are very rarely diagnosed based on a physical examination alone.…”