Malignant transformation of a conservatively managed incidental childhood cerebral mass lesion: controversy regarding management paradigm

BACKGROUND: Incidental findings on neuroimaging in the pediatric population are an emerging treatment challenge. Treatment options for these incidental childhood brain mass lesions, which radiologically may be assumed to be low-grade gliomas (LGG), vary, ranging from careful conservative `wait and scan` treatment to surgical biopsy, gross total resection, and upfront radiation and/or chemotherapy. As malignant transformation of LGG in children is extremely rare, some series advocate careful conservative management of these lesions; however, universal treatment protocols are not totally agreed upon. ILLUSTRATIVE CASE: We present the case of a 10-year-old boy with a fronto-basal incidental cerebral mass lesion, suspected to be a low-grade glial neoplasm. Initially, magnetic resonance imaging (MRI) was done to rule out a pathology causing his growth to be delayed. A treatment with growth hormone was initiated. After close clinical and radiological follow-up of this asymptomatic lesion for 6 years, a minimal growth of the lesion was seen, which we decided to continue following. After 7 years, a clear growth with new contrast enhancement was seen on routine MRI. At this point, the lesion was surgically resected. The diagnosis was, surprisingly, glioblastoma multiforme (WHO grade IV, BRAF V-600E mutation). DISCUSSION: Malignant transformation of LGGs in children is a very rare phenomenon. This is to our knowledge the first well-documented case describing malignant transformation of a suspected benign pediatric cerebral mass lesion, which did not undergo radiation, in a patient without a cancer predisposition syndrome (e.g., neurofibromatosis), with the transformation occurring after such a long follow-up period. The management of these lesions is still controversial. Unfortunately, radiological risk factors for malignant transformation of such lesions in the pediatric age group are lacking. CONCLUSION: Conservative treatment of incidental cerebral mass lesions in children seems a valid option. These lesions should probably be followed indefinitely, while carefully watching for changes in imaging characteristics.