Histopathologic Findings of Evolving Mpox Lesions

Abstract: This article reports two cases of the 2022 mpox virus with notable histopathology, and includes a novel description of mpox pseudotumor in the perianal region which is not previously described. This article additionally includes literature review of characteristic histopathology through evolving lesions, as it is sparsely described in relation to the 2022 mpox outbreak. Case one describes a 42-year-old man who presented with umbilicated, smooth papules on the trunk and extremities, and milia-like papules on the face. Histopathology of an umbilicated lesion revealed epidermal acanthosis with keratinocyte pallor, ballooning degeneration, keratinocyte necrosis, and neutrophilic epitheliotropism. Case two describes a 51-year-old man who presented with scattered eroded papules as well as a perianal mass. Histopathology of the mass revealed ulceration with keratinocyte enlargement and pallor with a mixed inflammatory cell infiltrate. It additionally revealed rare multinucleated keratinocytes with nuclear molding. These cases are remarkable and contribute to literature as reports of the histopathology of the atypical 2022 mpox outbreak are rare. A combination of clinical, laboratory, and histopathologic evidence is useful in diagnosing mpox, and these cases contribute to describing the evolution of viral lesions.