Malignant syphilis is now considered a rare disease, more commonly affecting individuals with poor health, malnutrition or HIV infection. We present a 34-year-old man with HIV infection who developed multiple atypical cutaneous ulcerations, leonine facies, a scleral nodule and keratitis with visual loss. The diagnosis of malignant syphilis was delayed due to the insidious presentation, but was confirmed via immunohistochemical (IHC) staining with anti-Treponema antibodies of a skin biopsy. Significant clinical improvement was observed following a 15-day course of penicillin and tigecycline therapy. In advanced HIV disease, cutaneous manifestations are often difficult to identify and present a challenge for the clinician. Clinical manifestations of secondary syphilis vary greatly, earning the epigram of 'the great imitator'. It is important to recognize atypical presentations of syphilis, especially among HIV-infected individuals. Unlike historical cases of malignant syphilis, Treponema pallidum was found in the tissue section using IHC staining methods. We emphasize the importance of lues maligna in the differential diagnosis of HIV-infected patients with diffuse ulceronodular lesions as well as the usefulness of histological investigations and IHC studies.