Imaging diagnosis of post-amputation neuroma of the sciatic nerve in a patient with osteosarcoma: A case report and literature review

Background: Post-amputation neuroma is a benign, non-neoplastic proliferation resulting from abnormal regeneration of injured peripheral nerves. In oncologic patients, these lesions may mimic tumour recurrence, posing a significant diagnostic challenge.
Case presentation: We report the case of a 13-year-old boy treated for proximal tibial osteosarcoma with neoadjuvant chemotherapy followed by limb amputation. Follow-up imaging revealed a well-defined lesion at the distal end of the sciatic nerve. MRI demonstrated a characteristic fascicular pattern with signal intensity similar to muscle on T1-weighted images and intermediate-to-high signal on T2-weighted images. The lesion showed homogeneous enhancement initially and subsequent cystic changes without enhancement on follow-up imaging. These findings favoured the diagnosis of presumed post-amputation neuroma.
Conclusion: Recognition of the imaging features of post-amputation neuroma is essential to avoid misdiagnosis as tumour recurrence. MRI plays a central role in characterization, allowing accurate diagnosis and preventing unnecessary invasive procedures.