When, if ever, would you consider hippocampal avoidance whole brain radiotherapy in the setting of leptomeningeal disease?  

Never. Unless it is nodular leptomeningeal disease recurrence after surgical resection.

In the setting of leptomeningeal disease, I would be concerned about under-covering areas of the brain when trying to spare the hippocampus. Also, the conformal techniques make it more difficult to ensure coverage of the brain surface. As such, I would avoid using hippocampal sparing WBRT in patient...

In general, I would not offer such a patient hippocampal avoidant whole brain radiotherapy. The two exceptions would be: Nodular "lepto" dissemination pattern following resection of a brain met and post-op SRS, which is not true leptomeningeal disease (with no disease in the proximity of the hipp...