1580 Endometrioid Adenocarcinoma Presenting With Hematochezia and an Extraluminal Rectal Mass

Abstract

INTRODUCTION: We present a case of primary endometrioid adenocarcinoma with invasion of the rectosigmoid colon, highlighting the importance of colonoscopy, biopsy, cross-sectional imaging, and a multidisciplinary approach to the management of extraluminal lesions. CASE DESCRIPTION/METHODS: A 47-year-old female with a history of lymphangioleiomyomatosis (LAM) was admitted for abdominal pain, hematochezia, tenesmus, and proctalgia following 7 months of abnormal bowel habits and 20 pounds of unintentional weight loss. Review of symptoms was negative for abnormal uterine bleeding. Examination revealed tenderness on palpation of the lower abdominal quadrants, and grossly bloody stool with digital rectal exam. Computed tomography (CT) of the abdomen and pelvis with contrast demonstrated circumferential rectal wall thickening with enhancement. Colonoscopy revealed an ulcerated extraluminal rectosigmoid mass, and biopsies were obtained. Magnetic resonance imaging (MRI) demonstrated a large heterogeneous mass involving the uterus and rectum with no discernable fascial plane. Initial pathology reported invasive adenocarcinoma without a primary origin delineated. A multidisciplinary conference prompted additional immunostaining of the sample, confirming endometrioid adenocarcinoma. The patient was diagnosed with International Federation of Gynecology and Obstetrics (FIGO) stage IVa endometrioid adenocarcinoma and underwent surgical management with adjuvant chemoradiation. Genetic testing demonstrated heterozygosity with a pathologic variant in the MutL homolog 1 (MLH1) gene consistent with Lynch Syndrome. Surveillance positron emission tomography scanning 6 months later revealed no evidence of disease recurrence. DISCUSSION: Extraluminal lesions are notoriously difficult to diagnose with endoscopy alone. In this case, cross-sectional imaging with CT and MRI was unable to differentiate the origin of the lesion, and pathologic examination without the clinical context of the extraluminal nature of the tissue obtained on colonoscopy delayed the definitive diagnosis. This case highlights the importance of a multidisciplinary approach to cases of suspected extracolonic malignancies with colonic invasion in order to expedite definitive diagnosis and treatment. There are no reports of concomitant Lynch Syndrome and LAM in the literature and the clinical significance is unclear. Further study may be helpful in elucidating potential links between these two uncommon conditions.