Endometrial Adenocarcinoma with Pattern of Invasion Resembling Adenoma Malignum

Endometrial adenocarcinoma with a glandular invasion pattern resembling adenoma malignum of cervix is a deceptively benign and highly differentiated form of endometrioid adenocarcinoma which can be resistant to radiation therapy and exhibit a deep invasion pattern. We report a 57-year-old female who was a biopsy-proven case of FIGO grade 2 endometrial adenocarcinoma with 4 cm cervical involvement, who underwent whole pelvic radiation therapy followed by hysterectomy. Her hysterectomy sections revealed conventional endometrioid adenocarcinoma with a deceptively bland pattern of well-spaced, branching glands with myometrial invasion up to 90%. Extensive lymphovascular space invasion was identified and cervical stroma was involved. Immunohistochemistry was consistent with an endometrial origin. The final diagnosis was endometrial adenocarcinoma with adenoma malignum pattern of invasion. It is not clear whether the gland morphology was due to radiation treatment however, the widespread and extensive invasion makes it imperative to recognize that these patients need to be vigilantly followed up. It is important to recognize this entity because these deeply invasive and benign appearing glands can be resistant to the conventional approach of radiation treatment and highlights the fact that the patient needs to be cautiously staged and accordingly treated. Keywords: Endometrial adenocarcinoma; Minimal deviation; Adenoma malignum; Uterus; Pelvic radiotherapy