Artikel
Differential diagnosis of MPNST vs. Neurinoma – Can PET-CT help?
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Veröffentlicht: | 13. Mai 2014 |
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Gliederung
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Objective: Malignant peripheral nerve sheath tumors (MPNST) are a rare entity, accounting for 5-10% of soft-tissue-sarcomas. However they are an important differential diagnosis to benign tumors of the peripheral nervous systems regarding treatment and prognosis. The worst prognosis is given if associated with neurofibromatosis I (NF I). MPNST are difficult to detect in NF I individuals. The objective of this study was to evaluate magnetic resonance (MR) imaging and FDG-PET as a diagnostic tool for MPNST in patients with and without NF I and to verify the diagnosis by pathology and clinical follow-up.
Method: Between 2007 and 2013 seven patients underwent surgical treatment in our department. Four of them are NF I individuals. In these patients we detected numerous tumors in MRI. We excised 13 tumors in 15 surgical procedures. The pre-operative diagnostic included CT-scan, MRI and partially F18FDG-PET-CT. The excised tumors have been processed histopathologically. Post-operative diagnostic included MRI and 18FDG-PET-CT. The size of the tumors in MR imaging and the maximum standard uptake value (SUVmax) in 18FDG-PET-CT have been assessed and correlated with the histopathological result and clinical follow-up was undertaken in all patients.
Results: The mean size of the benign tumors in MR imaging was smaller than that of the malignant tumors. Imaging from 18FDG-PET-CT and associated SUVmax of the suspected MPNSTs correlated with the histopathological diagnosis. A size over 5 cm in MR imaging and a SUVmax of more than 6.0 in 18FDG-PET-CT was closely correlated to malignancy of nerve sheath tumors.
Conclusions: On a limited number of cases we demonstrated the benefit from the use of MRI and 18FDG PET-CT scan to augment management of peripheral nerve sheath tumors, especially in the context of NF I, which is characterized by multiple tumors. Features suggestive of malignancy are a larger size and a higher tracer uptake. However, much larger numbers of MPNSTs are required to solve the problem of predicting the tumor grade.