Imaging features of anorectal proctitis in monkeypox infection

Abstract

The monkeypox outbreak of 2022 saw the first community-sustained transmission of the monkeypox virus outside of Africa, and rapidly developed into multi-country spread. A common presenting sign of monkeypox infection during this outbreak has been rectal pain due to proctitis. Proctitis with large hypoattenuated anorectal ulcers on CT scan should invoke consideration for monkeypox infection in young homosexual or bisexual men with associated skin eruptions.

Keywords: Anorectal ulceration; Monkeypox; Proctitis.

Fig. 1

Axial images from contrast-enhanced CT scan of the abdomen and pelvis reveal (a) diffuse circumferential rectal mural thickening, hazy infiltrated perirectal fat, and presacral edema with discrete geographic non-enhancing hypoattenuated zones (white arrows) in the rectal (b) and anal wall (c) due to large ulcerations and (d) pelvic ascites (black asterisk). Several bilateral inguinal lymph nodes measuring up to 1 cm are seen on (c). Sagittal image (e) reveals the thickened enhancing posterior rectal wall (black arrow) contrasting a large anterior wall hypoattenuated ulcer (white arrow). Note prominent presacral edema (white asterisk). A small right pleural effusion is not shown.

Fig. 2

Axial image from contrast-enhanced CT scan 11 days later (a) shows decrease in mural thickening and anterior hypoattenuated ulcer. Sagittal image (b) shows decrease in enhancing posterior rectal wall (black arrow) and large anterior wall hypoattenuated ulcer (white arrow) compared with prior exam. Pelvic ascites resolved (not shown).