Atypical Mpox Presentation With Proctitis in a Puerto Rican Patient: A Case Report.

Mpox, formerly known as Monkeypox, is a viral illness that has spread beyond its previous endemic areas and is now reported in the Caribbean. This report describes a 32-year-old man from Puerto Rico with a history of Herpes simplex virus and human papillomavirus who went to the emergency room with pelvic pain, fever, fatigue, rash, and constipation. Three days later, the rash turned into pustules. A CT scan showed rectal inflammation, and PCR testing confirmed Mpox infection. The patient had recently traveled to Minnesota and reported unprotected sexual contact with an unknown male partner approximately one week before his symptoms began. Initially, the presentation was attributed to bacterial proctitis, which delayed the correct diagnosis. After supportive care with antivirals and topical treatment, symptoms improved, and he was discharged with home isolation instructions. This case illustrates how Mpox can resemble other sexually transmitted infections and highlights the importance of including it in the differential diagnosis when evaluating patients in Puerto Rico, where it is still uncommon. Because atypical Mpox may present with limited lesions, minimal systemic symptoms, and early anorectal complaints, it can be mistaken for more common STIs, underscoring the need for clinicians in low-incidence regions to remain vigilant.