Intestinal‑type mucinous carcinoma of the endometrium showing a polypoidal exophytic form: A case report.

Although endometrial cancer is a common malignancy in women, rare histological subtypes can pose diagnostic challenges. Primary endometrial intestinal-type mucinous carcinoma is a newly recognized subtype of endometrial cancer that differs from Müllerian-type endometrial mucinous carcinoma. The present case report documents a rare case of intestinal-type mucinous carcinoma of the endometrium showing a polypoidal exophytic form. The patient, an 80-year-old female, was incidentally diagnosed with a uterine tumor during a follow-up for vulvar Paget's disease. Clinical and imaging examinations revealed a localized mass within the uterine cavity. Hysteroscopy and subsequent histological examination confirmed the presence of intestinal-type mucinous carcinoma of the endometrium. Microscopically, the tumor displayed adenocarcinoma containing an intestinal-type glandular epithelium with mild nuclear atypia. It stained positive for the gastrointestinal markers mucin 2 and caudal type homeobox 2, and stained negatively for estrogen receptor α. The patient underwent surgery and adjuvant chemotherapy, with no evidence of recurrence at the latest follow-up 6 months after surgery. Endometrial intestinal-type mucinous carcinoma is a rare histological subtype of endometrial cancer. Differential diagnoses include Müllerian-type endometrial mucinous carcinoma, endocervical adenocarcinoma, metastasis from gastrointestinal tract adenocarcinoma and non-neoplastic gastric/intestinal metaplasia. However, the prognosis of endometrial intestinal-type mucinous carcinoma remains unclear due to limited reported cases. Existing evidence suggests a poorer prognosis compared with classical mucinous carcinomas of the endometrium. The present case, which is characterized by a polypoidal exophytic tumor without myometrial invasion, showed a favorable outcome. Further documentation and characterization of the aforementioned rare malignancy are necessary to enhance the understanding of its clinical physiology and outcomes. The present case report highlights the diagnostic challenges associated with intestinal-type mucinous endometrial carcinoma. The inclusion of this type of malignancy in the latest World Health Organization classification emphasizes the need for further comprehensive studies and case reports to expand the current knowledge on this rare histological subtype.