Unexpected CA 19-9 Elevation in a Patient With a Splenic Epithelial Cyst: A Diagnostic Challenge

Splenic epithelial cysts are rare, benign lesions often discovered incidentally. Although typically asymptomatic, they can sometimes present with elevated tumor markers, such as CA 19-9, raising concerns for malignancy. We report the case of a 44-year-old woman who was found to have elevated liver enzymes and CA 19-9 levels. Imaging revealed a unilocular splenic cyst. Laparoscopic splenectomy was performed, and histopathology confirmed a benign epithelial cyst. Postoperatively, CA 19-9 levels declined significantly. This case highlights the importance of considering benign etiologies in patients with elevated tumor markers and emphasizes the role of imaging and surgical pathology in establishing a diagnosis.