AN UNEXPECTED CAUSE OF FEVER, HEADACHE AND ELEVATED ERYTHROCYTE SEDIMENTATION RATE. A.N. Githaiga 1 , E. Anish 1 ; 1 University of Pittsburgh, Pittsburgh, PA (Tracking ID #76143) LEARNING OBJECTIVES: 1) To recognize sarcoid as a cause of central nervous system dysfunction in a patient without other systemic evidence of sarcoidosis. 2) To appreciate the value of performing a brain biopsy to establish a diagnosis of neurosarcoidosis when CSF analysis and neuroimaging are nondiagnostic. CASE INFORMATION: A hypertensive 50-year-old African American woman presented to the hospital with a one-month history of retro-orbital headache, recurrent fevers, chills, sweats and weight loss. Temperature on admission was 38 deg and her neurologic exam was non-focal. Initial labs were significant for WBC-11,800,PLT-610, 000 and ESR-148. A brain CT scan showed old lacunar infarcts. Lumbar puncture showed protein of 111mg/dl, white cell count of 3 and 79% lymphocytes. Viral, bacterial and fungal cultures were negative. Autoimmune serological markers were negative. A bone marrow biopsy was negative for malignancy and granulomatous disease. Serum ACE level was normal ( 29 Units/L.). Chest CT scan was normal, and abdominal CT scan revealed numerous small mesenteric and retroperitoneal lymph nodes that were not accessible for biopsy. The patient was started on empiric prednisone therapy for temporal arteritis at 60 mg per day despite negative bilateral temporal artery biopsies. She noted rapid improvement of her headache and resolution of her fevers and was discharged home. Over the next 8 weeks her ESR dropped to 22 and she remained asymptomatic. However, as the steroid dose was being tapered, the patient began to experience recurrence of headache and fevers, as well as gait and cognitive dysfunction. An MRI was performed that revealed multiple subcortical areas with increased signal. Repeat CSF analysis showed a white cell count of 28 with 89% lymphocytes and increased protein (79 mg/dl). Brain biopsy performed revealed focal perivascular lymphocytic infiltrates with non-necrotizing granulomas. Special stains for AFB and fungus were negative. A diagnosis of neurosarcoidosis was made. Her symptoms steadily improved with high dose solumedrol and subsequent oral prednisone. IMPLICATIONS/DISCUSSION: This case illustrates the importance of considering a diagnosis of neurosarcoidosis as a cause of fevers and CNS dysfunction in an individual who does not have other overt manifestations of sarcoid. In 5% of cases, neurosarcoid is the initial presentation of the disease. CNS presentations typically include cranial nerve palsies, meningitis, optic nerve dysfunction and neuroendocrine disorders (e.g. diabetes insipidus and central hypothyroidism). CSF findings are nonspecific and include elevated protein and mononuclear pleocytosis. Contrast enhanced MRI may reveal meningeal/cortical masses or hydrocephalus. As demonstrated in the case presented, neural tissue biopsy may be useful, revealing perivascular non-caseating granulomas, which while not diagnostic, will be highly suggestive in the appropriate clinical context. FOOLED BY FAT/PERPLEXED BY PROPOFOL. E. Gjersvik Cichowski 1 , H. Sakowski 1 , H. Hashish 1 , R. Baltaro 1 ; 1 Creighton University, Omaha, NE (Tracking ID #74955) LEARNING OBJECTIVES: 1) Recognize laboratory error in the measurement of serum bicarbonate.