Object The significance of radiation in the induction of @entity5 in @entity5513 ( @entity5513 ) after radiosurgery is unclear despite an increasing number of case reports. The authors describe a new case of verified malignant transformation in a @entity5513 (MTVS) and provide a new evaluation of such cases previously reported in the literature. Methods A 46-year-old @entity1 underwent subtotal resection of a right-sided VS in 2004. The histological characteristics of the lesion were typical and benign. In early 2007 Gamma Knife surgery (GKS) was performed to treat a residual enlarging remnant. The radiosurgery parameters included the following: target volume 3.5 cm(3), prescription dose 12 Gy, prescription isodose 45%, maximum dose 26.7 Gy, and coverage 97%. At 2 years' follow-up the lesion was enlarged to 5.2 cm(3), but by 5 years it had decreased to 2.3 cm(3). Six months later the lesion was 8.4 cm(3). Repeated surgery was performed, and a histological analysis revealed a @entity808 . The case was further managed with repeated GKS performed in the spring of 2013. At that time, the radiosurgery parameters included the following: target volume 3.5 cm(3), prescription dose 16 Gy, prescription isodose 45%, maximum dose 35.6 Gy, and coverage 91%. This Gamma Knife Department has treated a total of 205 @entity1 with VS (local incidence of MTVS 0.49%). A search of the literature published up to and including 2013 was performed using PubMed as well as more informal search methods. Results This @entity1 is the 29th reported case of MTVS after radiation therapy. Of these cases, 40.7% were @entity1 with @entity4786 ( @entity4786 ). In those cases in which histology showed @entity5 with previously benign characteristics, totally conforming to the criteria for MTVS, the mean delay to malignant expression was 68 months (median delay 72 months). The authors also retrieved papers reporting 30 cases of malignant VS in @entity1 who had not undergone radiation treatment. Five of those cases were malignant transformation of a benign entity, and in 4 of them histology had verified that the initial disease was benign. In those 4 cases, there was a mean delay to malignant expression of 7.2 months (median delay 8 months). Conclusions Despite more frequent reports of MTVS after radiation treatment recently, there has been no accurate quantification of the risk, except in @entity1 with @entity4786 , in whom the incidence of @entity5 is high in relation to the numbers treated. The present analysis indicates that the risk of @entity5 over 20 years in cases in which no radiation treatment has occurred is 1.32-2.08 per 100,000, and this risk decreases to 1.09-1.74 per 100,000 if cases of @entity4786 are excluded. After radiation treatment, the overall risk over 20 years is 25.1 per 100,000, and this risk decreases to 15.6 per 100,000 if cases of @entity4786 are excluded. Radiation treatment increases the risk by approximately 10 times in non- @entity4786 cases.

Malignant transformation in XXXX : report of a single case, literature search, and debate.

@entity1 :: ('9606', 'Species') :: ['woman', 'patients', 'patient'] @entity808 :: ('MESH:D009442', 'Disease') :: ['malignant peripheral nerve sheath tumor'] @entity5513 :: ('MESH:D009464', 'Disease') :: ['VSs', 'vestibular schwannomas', 'vestibular schwannoma'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumors', 'malignancy'] @entity4786 :: ('MESH:D017253', 'Disease') :: ['neurofibromatosis', 'NF']
@entity5513 :: (MESH:D009464,Disease) :: ['vestibular schwannoma']
