Diagnosis of peritoneal pseudomyxoma using endoscopic ultrasound-guided fine-needle aspiration.

An 86-year-old woman presented with abdominal pain and ascites. Contrast-enhanced computed tomography revealed ascites, thickening of the greater omentum, mild peritoneal thickening, and a low-density tylosis-like cyst in the pelvic peritoneum. To achieve a definitive diagnosis, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) of the ascitic fluid and peritoneal lesions was performed. Histopathological analysis of aspirated fluid and peritoneal biopsy specimens confirmed the diagnosis of peritoneal pseudomyxoma (PMP). In this case, EUS-FNA played a crucial role in accurately diagnosing PMP as the underlying cause of idiopathic ascites.