Late malignant transformation of vestibular schwannoma in the absence of irradiation: case report

Abstract

abbreviatioNs MPNST = malignant peripheral nerve sheath tumor; NF2 = neurofibromatosis Type 2; SRS = stereotactic radiosurgery; SRT = stereotactic radiotherapy; VS = vestibular schwannoma. Late malignant transformation of vestibular schwannoma (VS) following irradiation has previously been reported 29 times in the literature. Here, the authors report the first late malignant transformation of VS unrelated to neurofibromatosis or radiation exposure. After undergoing a near-total excision of a histologically benign VS, the patient developed malignant regrowth of the tumor remnant 42 months after the primary excision. This case challenges the dogmatic belief of absolute causality between radiation exposure and late malignant transformation of VS, and has important implications regarding future counseling and consent for the treatment of patients with VS.

A rare case of intravascular schwannoma

“…There are several theories as to the origin of an intravascular schwannoma: invasive growth from an adjacent dermal tumor, tumor embolization, or metastasis . Malignant transformation of schwannomas, referred to as neurofibrosarcoma, neurogenic sarcoma, or malignant peripheral nerve sheath tumor (MPNST), is exceedingly rare, and therefore metastasis is a less likely etiology for these intravascular tumors. As this tumor is benign, there is no need for further invasive surgical treatment unless recurrent or symptomatic.…”

Transition of a vestibular schwannoma to a malignant peripheral nerve sheath tumor with loss of H3K27 trimethylation after radiosurgery—a case report and review of the literature

“…The transformation of a vestibular schwannoma into a malignant peripheral nerve sheath tumor after radiosurgery has been described in several cases before, as listed in Table 1 . On the contrary, two cases of spontaneous malignant transformation without irradiation from benign schwannoma to malignant peripheral verve sheath tumor have also been reported [ 11 – 13 ]. Therefore, role of radiation therapy in malignant progression has been argued [ 14 ].…”

Spontaneous transformation of vestibular schwannoma into malignant peripheral nerve sheath tumor

“…The most recent description of the spontaneous transformation of VS into MPNST presented by Bashir et al . [ 8 ] a relapse of the tumor (malignant this time) was documented 42 months after the initial surgery. The patient had been monitored for 9 months, by the time, the case report was submitted with no signs of tumor recurrence after irradiation.…”