A rare case of pulmonary sequestration with elevated CA19-9 levels.

Introduction: Carbohydrate antigen 19-9 (CA19-9) is a tumor marker that is primarily linked to gastrointestinal cancer, especially to pancreatic cancer. Lung sequestration is a rare congenital anomaly, The link between them is not well-established. Case presentation: A 62-year-old male was found to have elevated CA19-9 levels, which were increased to 1524.93 U/ml. Despite this significant rise, the patient did not exhibit any notable symptoms. Imaging studies indicated the presence of left lung sequestration accompanied by infection and enlarged retroperitoneal lymph nodes, while further tests pointed towards a benign pancreatic lesion. A multidisciplinary team decided on surgical intervention, opting for a lobectomy. Following the surgery, the patient's CA19-9 levels decreased significantly, and after 3 months of follow-up, they returned to the normal range. Discussion: This case emphasizes the importance of recognizing elevated CA19-9 as a potential sign of underlying conditions, such as lung sequestration, and illustrates the effectiveness of surgical treatment in these scenarios. Conclusion: The findings highlight the necessity for comprehensive investigations in patients with unexplained elevations in CA19-9 to ensure prompt diagnosis and treatment.