BACKGROUND:Differentiating radiation necrosis (RN) from tumor progression is challenging despite advanced neuroimaging techniques. We collected a consecutive series of surgically resected RN with presumptive diagnosis of recurrent/refractory brain metastasis (BM) after radiation therapy (RT) and performed a descriptive analysis of characteristics and clinical courses. METHODS:From 107 patients who underwent surgery to remove previously irradiated BM, we retrieved 18 patients with pathologically confirmed pure RN. RESULTS:Sixteen patients (89%) had preoperative MRI suggesting recurrent/refractory BM in accordance with clinical suspicion, and 14 (78%) patients showed radiological response after RT before progression. The median time from RT to surgery was 28.5 months (range 6-94 months). RT doses varied from 1,800 cGy/single fraction to 8,300 cGy/21 fractions. Lobulated/irregular shape, central necrosis, and substantial increase of perilesional edema were dominant MRI features. Neurological symptoms improved or stabilized in 13 patients (72%) after surgery. Five cases of distant recurrences occurred in patients with uncontrolled systemic cancer, except for one patient with controlled small cell lung cancer who recurred as a leptomeningeal metastasis. One patient had multiple enhancing lesions along the surgical cavity, suggesting local recurrence. Median overall survival after surgical removal of RN was 34 months (range 4.3-132 months), and eight out of eleven patients with controlled systemic cancer remained alive at last follow-up. CONCLUSION:RN frequently mimics recurrent BM despite advanced imaging. Surgical resection provides both definitive diagnosis and symptomatic benefit in selected patients. However, distant recurrence of BM could happen in patients with uncontrolled systemic cancer.
MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes) syndrome is a multi-systemic genetic disorder characterized by mitochondrial dysfunction, often presenting with diverse clinical phenotypes. We report a rare case of glioblastoma (GBM) in a 60-year-old female whose MELAS manifestations were primarily metabolic and neuro-sensory. Her clinical course began at age 40 with diabetes mellitus, bilateral sensorineural hearing loss, and left ophthalmoplegia. She was diagnosed with MELAS syndrome by molecular genetic testing at age 56 following her son's diagnosis. Despite the absence of previous stroke-like episodes, she presented with an acute 2-day history of headache, vomiting and altered mental status. Brain MRI revealed a mass lesion, and subsequent gross total resection was performed. Histopathological and molecular analysis confirmed a GBM, IDH-wildtype (CNS WHO grade 4). Despite surgical resection, the patient failed to recover neurologically, remaining in a stuporous state with eye opening but inability to follow commands. She subsequently received the Stupp protocol; however, massive local recurrence with increased relative cerebral blood volume was observed within one month of treatment initiation, indicating rapid and aggressive tumor progression. This case underscores that in MELAS patients, primary brain malignancies can arise independently of typical stroke-like episodes. In addition, the unusually aggressive clinical course and rapid recurrence despite standard Stupp protocol therapy raise the possibility that altered mitochondrial metabolism may influence tumor behavior or treatment response in certain patients.
