Inguinal hernia is a common disease worldwide, but coexistence of malignancy is rare, ranging from 0.03 to 0.5%. Previous study showed primary tumor sites are mainly from gastrointestinal tract (40%), followed by ovary (20%), prostate (13%) and mesothelium (13%).In this study, we presented the largest case series of cancer found synchronously in inguinal hernia in Asia and second large case series in the world.

Between July 2011 and July 2022 ,a total of 4474 cases received inguinal hernia surgery and only 14 cases were found to have newly discovered hernia sac tumor. Demographic data were collected from their medical records. Histological review were conducted on all pathologic specimens by two experienced pathologists. Follow-up with the patient till the last clinic visit was finished.

13 patients (12 men and 1 woman, 0.29% of the total number) comprised the study group.The mean age was 77 years (median, 77 years; range, 60 to 90 years).The presenting symptoms and signs included a palpable mass within the hernia (61%), pelvic pain (53%), and non-reducible mass (23%). Gastrointestinal adenocarcinomas comprised 53% of the metastatic tumors.Two malignant myxoid soft-tissue neoplasms, one lymphoma two pseudomyxoma peritonei were found in hernia sac.The mean survival was 39.2 months after hernia repair (median, 16 months; range, 0.3 to 128 months).In patients with suspected cholangiocarcinoma the average survival was 0.3 months followed by gastric cancer (mean, 4 months; range, 2 to 8 months), colon cancer (mean, 11.5 months). The survival in patients with myxoid soft-tissue neoplasms (mean survival, 55.5 months), peritonei (mean, 45 months), and prostate primaries (one patient survived 128 months). Two patients with pseudomyxoma peritonei are still alive with disease.

All hernia surgery patients do not require routine histologic examinations of their hernias.The majority of the metastatic cancers had the worst prognosis and originated in the gastrointestinal tract.