Purpose: To analyse the appearance of primary and recurrent malignant peripheral nerve sheath tumours (MPNSTs) in magnetic resonance imaging (MRI) with a focus on configuration, and to assess the occurrence of loco-regional post-treatment changes and metastases during post-treatment follow-up.
Material and methods:Twenty patients with histologically proven MPNST underwent post-treatment 1.5 T MRI. Primary and recurrent MPNSTs were examined for configuration, contrast enhancement, extent, and signal intensity in MRI. Loco-regional post-treatment changes and information on metastases were extracted from the follow-up.Results: MPNSTs occurred most often in the extremities (p = 0.006). Twenty per cent (n = 4) of the patients developed recurrences, with a total of 24 lesions. Recurrent MPNSTs were significantly smaller than primary MPNSTs (p = 0.003). Primary MPNSTs mostly occurred unifocally as multilobulated or ovoid and heterogeneous lesions with mostly well-defined borders. Recurrent MPNSTs purely occurred multifocally as mostly nodular (p < 0.001), multilobulated, or ovoid lesions. 80%, 65% and 30% of the patients showed post-treatment subcutaneous oedema (p = 0.002 to 0.03), muscle oedema (p = 0.02), and seroma, respectively. Twenty-five per cent (n = 5) of patients presented metastases during follow-up. The relative risk in patients with recurrences to develop lung or lymph node metastases is eightfold (p = 0.056).Conclusions: While primary MPNSTs mostly appear unifocally as multilobulated or ovoid lesions, recurrent MPNSTs purely occur multifocally as mostly nodular lesions. Subcutaneous and muscle oedema are very common locoregional post-treatment changes. Patients with recurrences have a higher risk for lung and lymph node metastases.
Background
Adult fibrosarcoma (AFS) is a very rare malignant soft tissue tumor, arising from malignant spindle-shaped fibroblasts. We aim to analyze the appearance of recurrent AFS with a focus on configuration and to assess the occurrence of loco-regional post-treatment changes on MRI follow-up.
Methods
One hundred sixty-eight MRI follow-up scans (1.5 T MRI) of 12 patients with histologically proven AFS were reviewed. The recurrent tumors were examined for configuration, limitation, contrast enhancement, and extent and signal intensity on MRI.
Results
The mean age of the patients was 50.2 ± 16.7 years. Forty-two percent of the patients presented recurrent AFS (n = 5). Recurrences occurred 12 ± 6.5 months after tumor resection in the mean. Patients over 55 years of age showed a significantly higher risk for recurrences (RR = 5; 95% CI, 1.8 to 31; p = 0.04). Recurrent AFS was ovoid, nodular, streaky, polycyclic, or fascicular configured with homogeneous/heterogeneous contrast enhancement and well- or ill-defined borders. The intensity of contrast enhancement ranged from rim to marked contrast enhancement. Recurrent AFS mostly showed a muscle iso-intense signal in T1-weighted and a hyperintense signal in PD-weighted/TIRM sequences. The most common post-treatment changes were subcutaneous edema (92%; p = 0.03), muscle edema (75%), and postoperative seroma (50%). Patients with the presence of muscle edema after primary tumor resection had a slightly, but not significantly higher risk for recurrences (RR = 1.75; p = 0.08).
Conclusion
Recurrent AFS shows no common configuration on MRI, as it may appear ovoid, nodular, streaky, polycyclic, or fascicular. Patients with the presence of post-treatment muscle edema have a slightly higher risk for recurrences.
Level of evidence: Level III, therapeutic study
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