We describe an HIV-negative 43-year-old woman presenting with a diffuse ulceronodular eruption and positive serological tests for syphilis consistent with lues maligna. Lues maligna is a severe and rare variant of secondary syphilis characterized by prodromal constitutional symptoms followed by the formation of multiple well-circumscribed nodules with ulceration and crust. This case depicts a particularly rare presentation as lues maligna usually involves HIV-positive men. The clinical presentation of lues maligna can pose a diagnostic challenge, with infections, sarcoidosis, and cutaneous lymphoma as just a few entities in its broad differential diagnosis. However, with a high index of suspicion, clinicians can diagnose and treat this entity earlier and reduce morbidity.