[Multimodal Therapy of Recurrent Malignant Schwannoma]

Malignant peripheral nerve sheath tumor schwannoma (MPNST), also known as malignant schwannoma, is a very rare tumor accounting for only 2% of all sarcomas. The prognosis is relatively poor, with a 5-year survival rate of 46-69%. The treatment of MPNST has not been standardized yet. Mainstay treatment is radical resection. Oncological adjuvant or neoadjuvant treatment has equivocal indications with unclear effects.

The case report presents a 55-year-old patient who showed resistance in the medial-ventral area of the left lower limb. An MRI scan showed a tumor adjacent to the femoral nerve. Tumor extirpation was performed. Histology revealed malignant schwannoma (MPNST) and the resection was assessed as R0. Postoperative whole-body PET/CT revealed no viable tumor tissue. The patient was regularly followed-up. On a follow-up MRI scan, performed 53 months after initial surgery, tumor recurrence was detected in the left thigh. Extirpation of the recurrent tumor was performed. Histology confirmed MPNST and the resection radicality was assessed as R2. Postoperative PET/CT revealed tumor residues. Therefore, 58 months after the initial surgery, another operation of the residual tumor was performed with R0 resection. Three applicators for interstitial brachytherapy were placed in the resection cavity. Following the operation, radiotherapy with an interstitial brachytherapy boost of 18 Gy followed by external fractionated radiotherapy of 50 Gy were administered. The latest MRI scan, performed 66 months after the diagnosis of MPNST, showed no tumor tissue. The patient had no neurological deficit.

The mainstay of treatment for MPNST is radical en bloc resection. The use of subsequent oncological therapy depends on the radicality of the resection. In our case, because of the good radicality of the initial surgery, adjuvant oncological therapy was postponed. As part of recurrence management, we again attempted to achieve the most radical resection possible and then apply adjuvant radiotherapy. In MPNST, as in all soft tissue sarcomas, high doses are chosen because of potential radioresistance. Given the confined nature of the disease, we chose this locally intensified therapeutic strategy, which resulted in this case in disease remission. Due to the low incidence of MPNST, it is not possible to test the efficacies of individual oncologic therapeutic procedures in larger patient cohorts.Key words: malignant schwannoma - soft tissue sarcoma - multimodal therapyThe authors declare they have no potential confl icts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 13. 3. 2016Accepted: 25. 4. 2016.