Mpox Presenting as an Anorectal Disease: A Case Report.

Mpox (monkeypox) is an emerging viral infection with a broad and evolving clinical spectrum that increasingly spans beyond its characteristic cutaneous manifestations. Anorectal manifestations are well recognized in patients with Mpox in recent outbreaks. However, the gastrointestinal (GI) or anorectal symptoms may precede the typical rash, creating significant diagnostic challenges and delaying appropriate infection control measures. We describe a quinquagenarian man with poorly controlled diabetes mellitus who presented with fever, diarrhea, tenesmus, and severe perianal pain. Cross-sectional imaging demonstrated diffuse rectosigmoid inflammation, while endoscopy revealed severe ulcerative proctitis. Initial evaluation favored acute infectious proctitis, and treatment was directed accordingly. However, the subsequent development of disseminated pustular skin lesions prompted consideration of Mpox, which was ultimately confirmed by polymerase chain reaction testing of the lesions. Extensive testing excluded concurrent human immunodeficiency virus (HIV) infection and other common sexually transmitted infections, and rectal biopsy demonstrated nonspecific acute colitis. The patient recovered with supportive management and had complete endoscopic resolution on follow-up colonoscopy. This case illustrates the relevance of considering Mpox in the differential diagnosis of acute proctitis and lower GI symptoms, even before characteristic skin lesions appear. It also underscores the diagnostic value of maintaining a high index of suspicion in patients presenting with severe anorectal disease and points out that diabetes-associated immune dysfunction may play a role in such cases. Early recognition of atypical GI manifestations is essential for timely diagnosis, appropriate patient isolation, avoidance of unnecessary interventions, and optimal clinical outcomes.