Umbilical hernia as the initial manifestation of pseudomyxoma peritonei: a case report.

Pseudomyxoma peritonei (PMP) is a rare peritoneal malignancy. Its typical clinical manifestations include abdominal distension, increased abdominal girth, or abdominopelvic masses. It is extremely rare for an umbilical hernia to be the initial manifestation, so this can easily lead to clinical misdiagnosis. A 60-year-old woman presented with a reducible umbilical mass for 10 months. Physical examination revealed marked abdominal distension and a 6-cm firm, irreducible umbilical mass. Serum tumor markers were normal. Computed tomography (CT) showed diffuse low-density abdominopelvic masses consistent with PMP, an appendiceal cystic lesion suggestive of mucinous neoplasm, omental thickening, and periumbilical tumor extension. Ultrasound revealed 9.4-cm ascites with mucin particles and septations. She underwent cytoreductive surgery with hyperthermic intraperitoneal chemotherapy. Intraoperatively, extensive gelatinous mucin, a ruptured cystic appendix, and periumbilical tumor involvement were noted. Postoperative pathology confirmed a high-grade appendiceal mucinous tumor with PMP. The immunohistochemistry results were as follows: cytokeratin 20 positive, caudal type homeobox 2 positive, and Ki-67 labeling index of 30%. Telephone follow-up 3 months after surgery indicated that the patient was doing well. PMP presenting with umbilical hernia as the initial symptom is relatively rare and is often misdiagnosed as a simple umbilical hernia. For middle-aged and elderly female patients with umbilical hernia who have concurrent ascites, thickened peritoneum, or a hard and fixed hernia mass, abdominopelvic CT and ultrasound should be performed to rule out PMP to avoid blindly performing hernia repair and delaying diagnosis and treatment.