Primary phrenic nerve tumors: a systematic review

Abstract Introduction Phrenic nerve tumors are exceptionally rare. Their scarcity has precluded the development of evidence-based management guidelines. As a result, major uncertainties persist across nearly all aspects of diagnosis, management, and functional preservation. This study addresses these gaps by systematically reviewing reported cases of primary phrenic nerve tumors. Methods A comprehensive search of PubMed/MEDLINE and Google Scholar was performed from inception to February 2026. Eligible studies included English-language case reports, case series, and observational studies of patients with confirmed primary phrenic nerve tumors. Two reviewers independently screened studies, extracted data, and resolved discrepancies by consensus. Extracted variables included demographics, clinical presentation, imaging, pathology, management, diaphragmatic function, follow-up, and outcomes. Data were summarized descriptively using SPSS version 26.0. Results The systematic review included 29 cases of primary phrenic nerve tumors, with 19 female patients and a mean age of 48.36 ± 13.33 years. Respiratory symptoms were reported in 11 cases, while 5 were incidental findings. Thoracic involvement was noted in 18 cases, and CT was used in 25 cases. Schwannoma was reported in 22 cases, and open surgery was performed in 24 cases. Postoperatively, 10 patients had no postoperative complications, whereas 8 developed hemidiaphragm palsy. At follow-up, 21 patients had resolution of symptoms. Conclusion Primary phrenic nerve tumors are rare and heterogeneous, and may present with respiratory symptoms or be found incidentally. Most are benign nerve sheath tumors, especially schwannomas, and may be located in the thoracic segment more often, although cervical involvement can also occur. CT and MRI are used for evaluation, while histopathology confirms the diagnosis. Surgical resection is the main reported treatment, with nerve-sparing approaches used when possible. Postoperative diaphragmatic function varies and depends on tumor and surgical factors. Current evidence is limited and heterogeneous, and further standardized reporting and longer follow-up are needed.