68 Ga-DOATATOC Brain PET/CT Imaging in a case of Dural Metastasis from Synovial Sarcoma.

We present the case of a 70-year-old male patient who underwent a gallium-68 ( 68 Ga)-DOTATOC brain positron emission tomography (PET)/computed tomography (CT) for the assessment of a tumorous lesion on the dura. The patient had previously undergone below-knee amputation due to a mass of synovial sarcoma on the left foot and completed adjuvant chemotherapy approximately 3 months ago. Subsequently, a well-demarcated papillary solid mass located on the dura was surgically excised. Pathological examination confirmed that the dural metastasis originated from synovial sarcoma and post-operative magnetic resonance imaging (MRI) revealed no residual tumor. We conducted a 68 Ga-DOTATOC brain PET/CT suspecting a meningioma given the presence of a dural mass. The result showed lower uptake (maximum standardized uptake [SUV max 4.9]) than the pituitary gland (SUV max 9.3). Thus, we successfully conducted a differential diagnosis of metastasis from the preexisting malignancy rather than the meningioma. 68 Ga-DOTATOC PET/CT is a valuable tool for the differential diagnosis of meningioma. However, metastasis should also be considered, especially in patients with a history of malignancy and lesions showing mild 68 Ga-DOTATOC uptake.