Appendiceal cancer leading to intussusception detected incidentally during follow-up for Peutz–Jeghers syndrome

Peutz–Jeghers syndrome is an autosomal dominant disorder characterized by hamartomatous polyposis, pigmentation, and malignant tumors. We report a case of ileocecal carcinoma that was incidentally detected during follow-up for Peutz–Jeghers syndrome. A 39-year-old man with solitary Peutz–Jeghers syndrome had undergone three abdominal surgeries. He had been followed up via upper and lower gastrointestinal endoscopy and small intestinal endoscopy. In the endoscopic examination of the lower gastrointestinal tract, a 35 mm large, bumpy, elevated lesion was observed in the cecum. This lesion was not observed 9 months earlier during lower endoscopy. Biopsy of the specimen confirmed tubulovillous adenoma and carcinoma. This lesion was judged to be an indication for operation, and we performed ileocecectomy + D3 lymph node dissection. From the excised specimen, poorly differentiated carcinoma and adenoma components in contact with Peutz–Jeghers-type polyps in the appendix were recognized. A review of the computed tomography image obtained 2 years ago confirmed appendiceal swelling. We suspect that the ileocecal carcinoma in the appendix may have rapidly developed within the 9 months, and was incidentally detected on lower endoscopic examination during follow-up. For the prevention of appendicular tumorigenesis, prophylactic appendectomy may be considered in certain cases during follow-up for Peutz–Jeghers syndrome.