Severe Anorectal Mpox With Newly Diagnosed HIV and Syphilis: A Diagnostic and Management Challenge

TL;DR

A 25-year-old man with severe anorectal mpox also had undiagnosed HIV and syphilis, highlighting the challenges in diagnosing and managing overlapping STIs.

Contribution

This case highlights the diagnostic challenges of mpox when co-occurring with undiagnosed HIV and syphilis.

Findings

Mpox lesions in anorectal and genital regions were confirmed by PCR testing.

The patient had undiagnosed HIV with severe immunosuppression and latent syphilis.

The case emphasizes the need for comprehensive sexual health screening and early antiviral treatment.

Abstract

Mpox has re-emerged globally in non-endemic regions, challenging clinicians with diverse mucocutaneous manifestations that frequently mimic other sexually transmitted infections (STIs). Early genital and anorectal lesions may resemble herpes simplex virus or syphilis, often resulting in diagnostic error and treatment delay. Lesion distribution frequently corresponds to the route of transmission, further complicating clinical recognition. We describe a 25-year-old male who presented with diffuse pustular and vesicular eruptions, including extensive anorectal and genital involvement, confirmed as Mpox by polymerase chain reaction (PCR) testing. Additional evaluation revealed previously undiagnosed HIV infection with marked immunosuppression and latent syphilis. This case underscores the diagnostic complexity and therapeutic urgency of Mpox in patients with concurrent STIs and highlights the necessity of comprehensive sexual-health screening, early antiviral initiation, and multidisciplinary management during ongoing outbreaks.

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