1/3. Malignant progression of benign brain tumors after gamma knife radiosurgery: is it really caused by irradiation?Malignant transformation of benign neoplasm after radiosurgery is usually diagnosed based on the initial presence of benign tumor, its exposure to ionizing radiation, elapsed time from radiation exposure to malignant progression, and different histological characteristics or growth rate of the regrowing tumor comparing with those originally treated. Three presented cases fulfilled these diagnostic criteria; however, it seems that progression of the tumors (schwannoma, meningioma, chordoma) resulted from the natural course of the disease, rather than represented side effects of gamma knife radiosurgery. Evaluation of the proliferative potential of the benign neoplasm before radiosurgical treatment either directly, if tumor sampling is available, or indirectly, by calculation of the tumor growth rate and/or analysis of the data of the metabolic imaging (PET, MRS) is important for identification of "aggressive" subtypes, precise prediction of prognosis, and confirmation of the radiation-induced malignant transformation in cases of tumor regrowth.- - - - - - - - - - ranking = 1keywords = radiation-induced (Clic here for more details about this article) |
2/3. Post-radiation intramedullary malignant peripheral nerve sheath tumor.We report the intramedullary growth of a malignant peripheral nerve sheath tumour (MPNST). A 50year-old man developed a severe tetraparesis over a 4-month period. Following irradiation of a chronic tonsillitis during his childhood, the patient had later experienced a number of post-radiation diseases, including a laryngeal cancer that required permanent tracheotomy. Before admission, a magnetic resonance imaging (MRI) study had disclosed a C4-C5 intramedullary lesion. On admission to our Department, the patient had a nearly complete tetraparesis. At surgery, the lesion was exposed through a posterior midline myelotomy. A friable neoplasm, with no clear plane of cleavage, was found. The tumour was subtotally resected. Histological examination, which intraoperatively had not yielded a specific diagnosis, eventually revealed a MPNST, grade intermediate, with ultrastructural and immunohistochemical features consistent with a schwannian differentiation. No postoperative radiotherapy was undertaken. The patient died 9 months later from pneumonial complications. MPNSTs may develop within the spinal cord similarly to their benign schwannian counterpart. The reported sequence of events might support a possible relation between irradiation of the spinal cord and induction, followed by malignant transformation, of intramedullary schwannosis. This unique case must be added to the growing list of radiation-induced spinal cord tumours.- - - - - - - - - - ranking = 1keywords = radiation-induced (Clic here for more details about this article) |
3/3. Development of flat adenoma and superficial rectal cancer after pelvic radiation.Little is known about the early development of rectal cancer in patients with radiation-induced colitis. We describe two patients with a history of radiation colitis who developed rectal cancer. The macroscopic appearance of these lesions suggested that they arose de novo, but the histologic findings were more consistent with progression along the adenoma-to-carcinoma sequence, a hybrid of de novo lesion and adenoma. Early rectal cancer associated with chronic inflammation should be considered if a nonpolypoid adenomatous lesion is detected in a patient who has received pelvic radiation.- - - - - - - - - - ranking = 1keywords = radiation-induced (Clic here for more details about this article) |