Malignant Peripheral Nerve Sheath Tumors of the Pericardium in a Patient with Neurofibromatosis Type 1: The Diagnostic Value of 18F-FDG PET/CT and 123I-MIBG SPECT/CT.

A 25-y-old woman with known neurofibromatosis type 1 and a large anterior mediastinal mass was investigated. 18F-FDG PET/CT revealed a radiotracer-avid anterior mediastinal mass having an SUVmax of 4.3 and demonstrating a hypoactive center. The 123I-metaiodobenzylguanidine SPECT/CT study performed subsequently did not demonstrate any uptake, thereby excluding, for the most part, the diagnosis of paraganglioma or neuroblastoma. At final pathology, a malignant peripheral nerve sheath tumor of the pericardium with areas of chondrosarcomatous and angiosarcomatous differentiation was diagnosed.