Article
Intraoperative ultrasound (iUS) pattern of rare peripheral nerve tumors – a correlation of morphology and histology
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Published: | May 13, 2014 |
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Objective: Peripheral nerve tumors are rare diseases, of them schwannoma are the most frequent entity. Both diagnosis and therapy of the remaining tumors are still discussed, since evidence based medicine is non existing. Meanwhile, ultrasound gained an important role in traumatic nerve lesions thereby allowing this experience to be transmitted to peripheral nerve tumors.
Method: Within a period of three years (2010–2013) 12 patients, whose nerve tumors were examinated with iUS using transducers of 15-17 MHz, were evaluated retrospectively. Those morphological results were correlated with histopathological findings (2x MPNST; 2x amyloidoma; 4x perineurioma; 1x B-CLL; 1x Lewis-Sumner-Syndrome, 1x regressive schwannoma, 1x solitary fibrous tumor). The last two cases were examined additionally with constrast enhanced ultrasound (SonoVue®).
Results: Comparing perineurioma, amyloidoma and Lewis Sumner Syndrome (LSS) in iUS, all of them revealed swollen hypoechoic fascicles. In amyloidoma those thickened fascicles showed altered size more frequently then those of LSS or perineurioma. In the one case of B-CLL iUS illustrated large, regular, hyperechoic fascicles without hyperperfusion. The one regressive schwannoma was very similar to MPNST revealing irregular hypo- iso and hyperechoic fascicles with cysts. While the solitary fibrous tumor was negative in perfusion pattern with SonoVue®, the regressive schwannoma had an irregular positive perfusion enhancement.
Conclusions: Neither MRI, PET CT, nor patients' symptoms are able to predict tumor malignancy. Especially concerning LSS, which is normally medically treated, prognostication would be essential. To gain a better understanding of those tumors, iUS criteria were compared to histological results. Until now iUS seems to distinguish MPNST from a regular schwannoma and neurofibroma, but comparing it to a regressive schwannoma, both seem to be very similar in iUS. In the future, despite the limited number of such cases, contrast enhanced ultrasound might become a valid additional and clarifying tool.