[A Case of Early Appendiceal Adenocarcinoma Coexisting with High-Grade Appendiceal Mucinous Neoplasm].

We report a case of a female in her fifties with early appendiceal adenocarcinoma coexisting with high-grade appendiceal mucinous neoplasm(HAMN)with a review of the literature. The patient presented to our hospital because of an enlarged appendix noted by contrast-enhanced CT performed for hematuria. Contrast-enhanced CT showed that the appendix had swollen to 10 mm and mucus had accumulated inside, which had no evidence of obvious malignancy. She was followed up on CT once a year. Four years after her first visit, she underwent laparoscopic appendectomy for a definitive diagnosis. There were no adhesions or inflammation in her abdominal cavity, and the appendix root was dissected with an automatic anastomosis device. Her resected specimen macroscopically showed mild wall thickening, but no obvious neoplastic lesion. Pathological examination revealed that in many areas centered on the tip of the appendix, highly columnar atypical epithelium with enhanced mucus production was densely proliferated in the form of glandular tubular and papillary. The nuclei of the proliferating epithelium were large and the fission image was conspicuous, but they remained in the mucosa. Pathological examination diagnosed as HAMN according to the WHO classification. The atypical epithelium in a small area at the tip was particularly strong in nuclear atypia, and showed a strong positive diffusely in p53, which was an image of well-differentiated tubular adenocarcinoma. The pathological diagnosis was V, Type 0-Ⅱb, 2 mm, tub1 in HAMN, pTis, Ly0, V0, Pn0, pPM0, pDM0, pRM0, R0. Six months have passed since the operation, but no recurrence has been observed.