Sigmoid cancer mimicking ovarian echotexture on transvaginal ultrasound: Case report with literature review

Abstract

Ultrasound is a first line imaging modality for the evaluation of female pelvic pain. Pelvic pain constitutes one of the most common reasons for presentation to the emergency department with increasing use of point of care ultrasound. Infrequently, point of care or formal ultrasound evaluation may lead to misdiagnosis of extraovarian disease. This can have serious consequences, especially if an extraovarian malignancy is mistaken for a normal ovary or an ovary with a benign process. We present a case of a 41-year-old female who presented to the emergency department for a chief complaint of pelvic pain and vaginal bleeding. Transvaginal ultrasound demonstrated a left adnexal mass, later characterized as a sigmoid colon cancer on MRI and pathology, simulating ovarian echotexture with peripheral hypoechoic components resembling follicles. This article will review the literature of various cases of extraovarian pathology misidentified as ovarian processes and highlight the importance of considering these extraovarian mimickers to prevent potential morbidity and mortality of a missed diagnosis.

Keywords: Ovarian malignancy; Ovarian mimics; Transvaginal ultrasound.

Fig. 1

Forty one-year-old-woman undergoing evaluation of pelvic pain and vaginal bleeding. (A, B) Transvaginal ultrasound images demonstrate a left adnexal mass measuring up to 3.1 cm in greatest dimension. Peripheral hypoechoic components (arrowheads), left adnexal location, and oval shape overall could be misconstrued to represent a normal ovary. This mass was later proven to be a sigmoid colon adenocarcinoma.

Fig. 2

Forty one-year-old-woman undergoing evaluation of pelvic pain and vaginal bleeding. (A, B) Transvaginal Doppler sonographic images demonstrate a left adnexal mass with branching vascularity(arrowheads). This mass was later proven to be a sigmoid colon adenocarcinoma.

Fig. 3

Forty one-year-old-woman undergoing evaluation of pelvic pain and vaginal bleeding. (A) Axial T2 MR image with fat saturation demonstrates a mildly hyperintense endoluminal sigmoid colon mass (arrowhead). (B) Axial T1 MR image demonstrates an intermediate intensity mass at the same location (arrowhead). This mass was later proven to be a sigmoid colon adenocarcinoma.

Fig. 4

Forty one-year-old-woman undergoing colonoscopy for a sigmoid colon mass. (A) An endoscopic photo shows a polypoid mass arising from the sigmoid colon wall (arrowhead). (B) A gross specimen photo shows the mass after after snare biopsy and resection (arrowhead).

Fig. 5

Low power view of pedunculated polyp demonstrating its overall villous architecture and mucin lake (within box).

Fig. 6

Representative image of the villous adenoma with diffuse, low-grade dysplasia characterized by hyperchromatic, elongated nuclei in a pseudostratified arrangement.

Fig. 7

High power view of mucin lake with floating malignant epithelium (arrows) and macrophages (arrowheads). The epithelial fragments demonstrate cribriform architecture and minimal cytologic atypia.

Fig. 8

Composite image exhibiting nuclear positivity for each tested protein (MSH6, PMS2, MLH2, and MSH1) of mismatch repair via immunohistochemistry.

Fig. 9

A flowchart illustrating differential considerations for extraovarian adnexal mass.

Fig. 10

(A) An illustration demonstrating a colon mass with a tubulovillous morphology and a stalk (black arrowhead). (B) A simplified illustration demonstrating a tubulovillous malignancy of the colon collapsing during application of pressure with a transvaginal probe. (Illustration courtesy of Alana Drummond).