MON-353 Vasogenic Cerebral Edema Associated with Radiation-Induced Necrosis Masquerading as Adrenal Insufficiency

Background Since the early 1960s dexamethasone has been the preferred corticosteroid for treatment of cerebral edema.  Duration of dexamethasone is dictated by symptom severity but courses typically range from weeks to, less commonly, months.  Prolonged courses can precipitate iatrogenic adrenal insufficiency.  While risk for adrenal insufficiency exists, cerebral edema can present with symptoms similar to adrenal insufficiency.  Clinical case A 77-year-old male with stage III squamous cell carcinoma of the lung in remission subsequently developed brain metastasis to the left frontal lobe.  He received stereotactic radiosurgery.  At the time of his radiosurgery, he was placed on oral dexamethasone (4 mg twice daily) to treat radiation-induced edema.  The patient attempted an 18 day steroid taper but encountered adverse symptoms of fatigue, weakness, and depressed mood which worsened over 7 days after completion.  The patient resumed oral dexamethasone. His symptoms resolved within 2 weeks.  Again steroids were discontinued and symptoms of weakness and depression recurred more severely and he developed new imbalance and a fall from standing height.  High-dose oral dexamethasone (4 mg every 6 hours) resumed and symptoms resolved.  At this time it was felt the patient’s symptoms stemmed from adrenal insufficiency and he was referred to endocrinology.  The patient was transitioned from his 4 mg daily dexamethasone regimen to oral prednisone 20 mg daily with a goal to taper to a BSA (1.71 m² DuBois DuBois) appropriate dose.  After 8 days of oral prednisone the patient developed progressive return of previous symptoms.  We increased his prednisone but symptoms worsened and included weakness, confusion, change in personality, foot drop, and tremor.  The patient underwent emergent head CT . It showed a 1.6 cm mass in the centrum semiovale with considerable edema occupying nearly the entire deep white matter of the left hemisphere.  Upon this diagnosis he was placed again on dexamethasone and had improvement in symptoms. Conclusions This case demonstrates the overlap between symptoms of cerebral edema and adrenal insufficiency which can delay diagnosis of worsening edema.  In this patient, the key to differentiating between adrenal insufficiency and brain pathology was the lack of symptom resolution while taking dexamethasone equivalent doses of prednisone.  In a patient with known brain pathology we recommend brain imaging if symptoms do not resolve with preferred agents for adrenal insufficiency (i.e.: hydrocortisone or prednisone).    References: 1.) Expert Panel on Radiation Oncology.  ACR Appropriateness Criteria pre-irradiation evaluation and management of brain metastases.  J Palliat Med.  2014 2.) Ly Kl, et al. Clinical Relevance of Steroid Use in Neuro-Oncology.  Curr Neurol Neurosci Rep.  2017 3.) Phillips KA, et al.  Neurologic and Medical Management of Brain Tumors.  Neurol Clin.  2018