Human Mpox Virus Proctitis With Persistent Rectal Ulcers on Sigmoidoscopy : ACG Case Reports Journal

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Human Mpox Virus Proctitis With Persistent Rectal Ulcers on Sigmoidoscopy

Choy, Alexa M. MD1; Lyudmer, Michael MD1; Su, Steven MD, PhD1; Remotti, Helen E. MD2; Zucker, Jason E. MD1; Jodorkovsky, Daniela MD1

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ACG Case Reports Journal 10(2):p e01002, February 2023. | DOI: 10.14309/crj.0000000000001002
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On July 23, 2022, the World Health Organization declared the 2022 Mpox outbreak a “Public Health Emergency of International Concern.”1 Mpox typically presents as fever, followed by the development of papular and ulcerative skin lesions and lymphadenopathy.2 Multiple systemic complications have been reported, including perianal lesions and proctitis,3–5 although these have rarely been evaluated endoscopically.


A 35-year-old man with a history of well-controlled HIV (CD4 >500, on dolutegravir and darunavir-cobicistat) presented to an emergency department with a new rash, severe rectal pain, and hematochezia. At baseline, he is independent in all activities of daily living. He is sexually active with male partners and has inconsistent condom usage.

Three weeks before his presentation, he developed subjective fevers, chills, and dyschezia (symptom day [SD] 0) (Figure 1). He went on to develop worsening rectal pain, dyschezia, and bloody stools mixed with mucous. On SD 19, he developed a new-onset rash that began with 2 discrete, nonpainful, nonpruritic papular lesions on the left arm that spread over the face, neck, and chest. He also reported a 20-lb weight loss since the onset of symptoms. He presented to the emergency department 2 days after the onset of rash.

Figure 1.:
Clinical timeline: A 35-year-old man with well-controlled HIV presents with new rash, rectal pain, and hematochezia, found to have severe Mpox proctitis. CT, computed tomography; TPOXX, tecovirimat.

On initial presentation (hospital day [HD] 0/SD 21), he was afebrile, hemodynamically stable with adequate oxygen saturation on room air. Physical examination revealed umbilicated papular lesions of varying stages over the left arm, face, and neck. Anorectal examination revealed no evidence of anal fissure, mass, or visible external lesions or ulceration. Despite no visible lesions, external palpation was exquisitely painful. Internal digital rectal examination was otherwise normal. Laboratory results revealed mild normocytic anemia with a hemoglobin level of 12.8 g/dL, with an otherwise normal complete blood cell count with a differential hepatic function panel and basic metabolic panel. Urinalysis as well as urine and urethral gonorrhea/chlamydia amplification tests were negative. Herpes simplex virus (HSV) 1 and HSV2 immunoglobulin (Ig) M and peripheral blood polymerase chain reaction (PCR) were negative. Clostridioides difficile and gastrointestinal pathogen panel PCR were negative, varicella zoster virus (VZV) IgM negative and IgG positive (immune), hepatitis A IgM and IgG negative, hepatitis C antibody negative, hepatitis B virus (HBV) surface antibody positive, HBV surface antigen negative, HBV core antibody negative, and RPR reactive, titer 1:2 consistent with prior infection.

Nonvariola orthopoxvirus real-time PCR was obtained on HD 0 and resulted positive on HD 4/SD 25, consistent with Mpox infection. On further questioning, the patient endorsed that a recent male sexual partner tested positive for Mpox through swab of penile lesions, suggestive of direct transmission through receptive anal sex. The patient initiated treatment with oral tecovirimat 600 mg twice daily on HD 3/SD 24. Computed tomography of the abdomen and pelvis without contrast was obtained on HD 4/SD 25 for persistent severe rectal pain, which revealed diffuse circumferential thickening of the wall of the rectum with surrounding inflammatory changes compatible with proctitis. Empiric ampicillin-sulbactam 3 g every 6 hours for rectal superinfection was added on HD 8/SD 29. Given persistent proctitis despite antiviral treatment, he underwent flexible sigmoidoscopy on HD 10/SD 31. A diffuse area of severely friable mucosa with contact bleeding was found in the rectosigmoid colon. A localized area of severe inflammation characterized by erythema, friability, mucus, and shallow ulcerations with exudate was found extending 15 cm from the anal verge (Figure 2). Biopsies were taken with a cold forceps for histology. Pathology revealed an ulcer with granulation tissue and marked acute and chronic inflammation (Figure 3); immunostains for cytomegalovirus, HSV1, and VZV were negative. Grocott methenamine silver stains were negative for fungi and acid-fast bacilli stain negative for acid-fast organisms. The patient was discharged on HD 12/SD 33 to complete his 14-day course of tecovirimat with oral oxycodone 5 mg every 6 hours as needed for pain control. His symptoms significantly improved within 2 weeks of discharge.

Figure 2.:
Severe proctitis characterized by erythema, friability, and shallow ulcerations with exudate.
Figure 3.:
Biopsy of rectal ulcer, 200× magnification, hematoxylin and eosin stain. Note prominent neutrophilic and lymphoplasmacytic inflammation with reactive endothelial cells lining capillaries in granulation tissue.


Mpox proctitis is an evolving entity that became well described during the 2022 human Mpox virus outbreak. In one case series from 16 countries, 14% of patients had proctitis or anorectal pain, and 73% had anogenital skin lesions.6 What is unclear is how many patients had proctitis without any external anal lesions. This case has several unique features. Although at least one other case has described Mpox proctitis in the absence of perianal lesions,7 the persistence of exquisite anorectal pain due to proctitis alone for over 1 month in this patient is striking. This case also uniquely demonstrates severe proctitis both endoscopically and histologically after the patient had already received 7 days of tecovirimat. These findings suggest a delay between the initiation of Mpox treatment with endoscopic remission of proctitis. Although this may call into question whether another etiology may have been the culprit for his symptoms, an extensive workup for inflammatory (such as ulcerative colitis) and infectious causes (viral, fungal, or bacteria) was negative. This, together with his sexual history and exposure to Mpox penile lesions, strongly supports Mpox as the primary cause for his proctitis. Furthermore, the patient's symptoms ultimately improved with completion of the 14-day course of tecovirimat and, to our knowledge, have not recurred. For patients not responding to supportive care management and tecovirimat, further evaluation (sigmoidoscopy or anoscopy) may be warranted to rule out additional etiologies.


Author contributions: A.M. Choy: manuscript preparation and is the article guarantor. M. Lyudmer, S. Su, J.E. Zucker, and D. Jodorkovsky: manuscript review. A.M. Choy: manuscript revision. H.E. Remotti: pathology slide preparation and photographs.

Financial disclosure: None to report.

Informed consent was obtained for this case report.


1. World Health Organization. Second Meeting of the International Health Regulations (2005) (IHR) Emergency Committee Regarding the Multi-Country Outbreak of Monkeypox. WHO: Geneva, Switzerland, 2022.
2. Di Giulio DB, Eckburg PB. Human monkeypox: An emerging zoonosis. Lancet Infect Dis. 2004;4(1):15–25.
3. de Nicolas-Ruanes B, Vivancos MJ, Azcarraga-Llobet C, et al. Monkeypox virus case with maculopapular exanthem and proctitis during the Spanish outbreak in 2022. J Eur Acad Dermatol Venereol. 2022;36(8):e658–60.
4. Yakubovsky M, Shasha D, Reich S, et al. Mpox presenting as proctitis in men who have sex with men. Clin Infect Dis. 2023;76(3):528–30.
5. Lucar J, Roberts A, Saardi KM, Yee R, Siegel MO, Palmore TN. Monkeypox virus–associated severe proctitis treated with oral tecovirimat: A report of two cases. Ann Intern Med. 2022;175(11):1626–7.
6. Thornhill JP, Barkati S, Walmsley S, et al. Monkeypox virus infection in humans across 16 countries—April–June 2022. N Engl J Med. 2022;387(8):679–91.
7. Gedela K, Da Silva Fontoura D, Salam A, et al. Infectious proctitis due to human Mpox. Clin Infect Dis. 2023;76(3):e1424–7.

Monkeypox; proctitis

© 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology.