Signet-ring cell carcinoma of the appendix presenting as diffuse uterine involvement: a case report and literature review.

BACKGROUND

Appendiceal signet-ring cell carcinoma (SRCC) is rarely encountered, and presentation with diffuse uterine involvement as the initial manifestation has not been systematically reported, posing significant risk of misdiagnosis as primary uterine malignancy.

CASE PRESENTATION: A 45-year-old woman presented with vaginal bleeding for 4 months. Preoperative CT demonstrated diffuse uterine myometrial thickening and appendiceal wall thickening. Curettage pathology revealed signet-ring cells with immunohistochemistry CK20+++/SATB-2+++/CK7-/PAX-8-, favoring gastrointestinal origin. Intraoperatively, the uterus was 16-week size with a firm, enlarged appendix and right ovarian involvement. Cytoreductive surgery (CRS) confirmed appendiceal SRCC with uterine and mesenteric metastases. Eight cycles of adjuvant 5-FU plus cisplatin were administered. First recurrence occurred at 32 months, treated with six cycles of 5-FU, carboplatin, and bevacizumab. At last follow-up (January 2026), overall survival exceeded 52 months with normalized tumor markers.

CONCLUSIONS

For patients with "uterine enlargement and ascites," appendiceal SRCC should be suspected. The enteric immunophenotype and right-sided ovarian dissemination pattern are diagnostic keys. Thorough surgery combined with chemotherapy can achieve long-term survival.