Discussion
Macroscopic leptomeningeal dissemination at DIPG progression has been reported in up to 30% of cases. 10-13
However, the real number is probably underestimated because a high proportion of patients at the end of life are not imaged and/or do not undergo an autopsy. Furthermore, when histologically studied, microscopic disease dissemination has been found in a greater proportion. Caretti et al examined autopsy material from 16 DIPG patients and observed subventricular dissemination in 63% of the patients. Consequently, the real overall incidence of at distance dissemination is not well established, but likely higher than reported.5,12,14
ReRT, although palliative, has shown to be a good salvage in a number of contexts (i.e. relapsed HGG, ependymoma) given its reasonable tolerance and clinical/radiologic benefit.1.7Fontanilla et alreported 6 patients treated with focal reRT (20Gy) at recurrence for the first time in 2012.2 Since then, several groups have reported similar positive experiences.3,151.Recently, Lu et al reported a meta-analysis on this topic reinforcing the role of palliative focal reRT specifically for DIPG.16 In patients with DIPG, focal progression is usually the rule and is responsible for most of the neurologic symptoms and ultimate clinical deterioration, reinforcing the use of focal reRT. Our case is singular because the patient presented metastatic asymptomatic progression. However, and as in other DIPG cases without dissemination, with further tumor growth he developed brainstem symptomatology. Given the presence of other tumoral lesions and the good initial disease response to upfront irradiation, we opted to administer CSI, being our goal to control both disease compartments (local and leptomeningeal). Fortunately our approach was very well tolerated, proved clinical and radiological response, extending his survival for 6 months. Of note, quality of life was remarkably good with no need for admissions and with good functionality until his last days.
Based on this experience, we conclude that until new and effective therapies are identified, CSI could be a safe and good palliative reRT strategy for patients with progressed disseminated DIPG.
Conflicts of interest: The authors declare no conflicts of interest