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Case Reports

Abstract

With the global outbreak of Mpox (previously known as monkeypox) since 2022, this contagious viral disease has been increasingly recognized by clinicians. Rash is commonly seen with a spectrum of manifestations from macules, papules to pox-like nodules. While several case reports and small series have been published, detailed histopathological characterization of skin lesions, particularly focusing on early lesions and eccrine duct/gland involvement remains largely unknown. Here, we present a case of a 36-year-old man sexually monogamous with a male partner. He developed inguinal lymphadenopathy, rash and blisters which started on his genitals, and subsequent fever. New individual blisters on both forearms, right flank, and left thigh occurred. A 4 mm punch biopsy was obtained of the right forearm rash. Histopathology showed vacuolar interface change, mild spongiosis, focal epidermal necrosis with mixed inflammation, papillary dermal edema, and superficial and mid-dermal perivascular lymphocytic inflammation. An unusual finding was that of eccrine duct and folliculosebaceous lymphocytic infiltration. No definitive viral cytopathic effects or multinucleated keratinocytes were seen. VCM swab for PCR of a penile ulcer and left medial thigh pustule confirmed Mpox infection.  Patient was treated empirically with tecovirimat. The pathology lacked the more developed findings of marked epidermal necrosis and viral cytopathic changes described in Mpox histopathology. We report this case to raise awareness that adnexal inflammation, including involvement of the eccrine ducts, may be an early pathologic finding and a clue to the diagnosis of Mpox in early lesions.