Rare double primary carcinoma in ileocecal region: cecal tubular adenocarcinoma combined with appendiceal goblet cell adenocarcinoma.

[BACKGROUND] Appendiceal goblet cell adenocarcinoma (GCA) is a rare malignant tumor originating from the appendiceal mucosa, with an insidious onset. Its biological behavior lies between that of a carcinoid tumor and an adenocarcinoma, and it has a relatively favorable prognosis but a high risk of long-term recurrence and metastasis. The coexistence of primary cecal tubular adenocarcinoma and appendiceal GCA is extremely rare, and poses challenges in diagnosis and treatment.

[CASE DEMONSTRATION] An 86-year-old male presented with a 2-month history of abdominal pain and diarrhea. Abdominal CT revealed thickening of the ascending colon wall, suggesting colon cancer. Laparoscopic right hemicolectomy was performed. Postoperative pathological examination confirmed primary cecal tubular adenocarcinoma combined with appendiceal goblet cell adenocarcinoma. Adjuvant chemotherapy was recommended, but the patient refused. Seven months later, lung metastasis was detected. Chemotherapy with "raltitrexed plus bevacizumab" was administered. During an 8-month follow-up, the patient remained in generally good condition.

[CONCLUSION] Appendiceal GCA is more common in middle-aged and elderly women and is associated with a good overall survival rate but a high risk of long-term recurrence and metastasis, especially in patients with distant metastases. The coexistence of appendiceal GCA and cecal tubular adenocarcinoma is exceedingly rare. This case report analyzes the clinical features, histological morphology, immunohistochemistry, and differential diagnosis of this condition to enhance understanding of this rare disease.