Fluorodeoxyglucose positron emission tomography (FDG-PET) is useful in the diagnosis of neurosarcoidosis

Abstract

A 45-year-old man presented with a progressive transverse spinal cord syndrome. MRI scanning revealed bitemporal and multiple spinal lesions with significant enhancement after gadolinium administration mimicking an acute disseminated encephalomyelitis. CSF analyses showed a lymphocytic pleocytosis. After treatment with high dose steroids clinical improvement was observed with a secondary decline shortly thereafter. MRI rescanning showed no remarkable alterations of the lesions. Further diagnostic work-up included a fluorodeoxyglucose positron emission tomography (FDG-PET) of the whole body to search for occult inflammation or neoplasia. The FDG-PET showed hypermetabolic foci corresponding to the lesions on MRI and additionally increased uptake in mediastinal and pulmonary hilar lymph nodes. A mediastinal lymph node was biopsied. Pathology was consistent with the diagnosis of sarcoidosis. The usual diagnostical tools to evaluate a sarcoidosis, such as serum angiotensin converting enzyme (ACE) and computed tomography of the chest were performed initially and revealed no pathological results. Therefore, in this case FDG-PET was crucial for the diagnostic work-up leading to an accessible inflammatory lesion outside the CNS for biopsy and the final diagnosis of sarcoidosis.