Pelvic schwannoma misdiagnosed as colorectal cancer metastasis and the corresponding diagnostic lessons: A report of two cases.

Schwannomas are neurogenic tumours originating from Schwann cells, and the vast majority of the tumours are benign lesions. Schwannomas are most commonly found in the head, neck and extremities; however, those occurring in the pelvis are rare. Due to the lack of specific clinical manifestations and radiographic features, pelvic schwannomas are difficult to detect and differentiate at an early stage. Cases of pelvic schwannomas coexisting with colorectal cancer have rarely been reported in both domestic and international literature. The current study presents two cases of pelvic schwannomas that were misdiagnosed as colorectal cancer metastases. Both lesions were initially identified as metastatic colorectal cancer during preoperative evaluation and were subsequently confirmed as schwannomas by postoperative pathological examination. This report analyses the causes of misdiagnosis, summarises the key distinguishing features between pelvic schwannomas and colorectal cancer metastases, and proposes a diagnostic algorithm for patients with colorectal cancer and pelvic masses of uncertain origin, with the aim of providing practical guidance for clinical practice.