Neuromuscular Choristoma-Associated Desmoid-Type Fibromatosis of the Brachial Plexus: Additional Evidence to Support a Nerve-Driven Mechanism

Background We have recently described circumferential nerve involvement of neuromuscular choristoma associated with desmoid-type fibromatosis (NMC-DTF) in cases involving the sciatic nerve, supporting a nerve-derived mechanism for the DTF. We wondered whether a similar growth pattern occurs in cases involving the brachial plexus (BP). Methods We reviewed all available MR imaging in patients diagnosed at our institution with NMC/NMC-DTF of the BP. We also performed a literature search of patients with NMC/NMC-DTF of the BP. Results In our clinical records, 4 patients with NMC of the BP were identified, and 3 of them developed NMC-DTF. All these 3 patients had MR imaging evidence of circumferential encasement of the BP. In the literature, we identified 15 cases of NMC of the BP, of which 12 had identified NMC-DTF. Four published cases included MR images, and only 2 of them were of sufficient quality for review. The single provided image in both cases demonstrated a similar pattern of circumferential encasement of the BP by the NMC-DTF. One additional case report was published without MR images but described circumferential involvement in the surgical findings. One unpublished case of NMC-DTF of the BP from an international radiology meeting also had this MRI pattern. Conclusions The MRI findings of circumferential nerve involvement in patients with NMC-DTF of the BP are similar to our previously reported data in patients with NMC-DTF of the sciatic nerve, providing further imaging-based support of a nerve-driven mechanism. Clinical implications are presented based on the proposed pathogenetic mechanism.