Recognizing Lues Maligna in Human Immunodeficiency Virus-positive Individuals

Lues maligna is an uncommon manifestation of secondary syphilis that occurs primarily in immunocompromised individuals, particularly those with human immunodeficiency virus infection. Its clinical resemblance to opportunistic infections and malignancies, including monkeypox (Mpox), poses a diagnostic challenge. A 25-year-old male who has sex with men (MSM) presented with clear, fluid-filled blisters that became purulent and subsequently developed into dark scabs covering most of his body. The cutaneous manifestations closely resembled Mpox. Accordingly, polymerase chain reaction (PCR) testing for Mpox was performed along with venereal disease research laboratory (VDRL) and Treponema pallidum hemagglutination assay (TPHA) testing to exclude Mpox as the suspected diagnosis. Mpox PCR results were negative, whereas VDRL and TPHA results were reactive. Histopathological examination demonstrated a lichenoid reaction with inflammatory infiltrates consistent with lues maligna. The patient was treated with benzathine penicillin (2.4 million international units, administered in three doses at weekly intervals). This case highlights the importance of accurate diagnosis in distinguishing lues maligna from Mpox.