Tertiary stage of syphilis is marked by a lesion called Gumma.

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The main concept here is recognizing the hallmark lesion of the late, tertiary stage of syphilis. In untreated infection, syphilis progresses from a primary chancre to a secondary rash, and years later to tertiary disease. The distinctive lesion of tertiary syphilis is the gumma—a soft, granulomatous, necrotic nodule that can form in skin, bone, liver, and other tissues and gradually destroy surrounding tissue. Gummas arise from a delayed-type hypersensitivity reaction to Treponema pallidum components and are relatively noninfectious compared with the active lesions seen earlier. Because the question focuses on what characterizes the tertiary stage, gumma is the best answer. A chancre is the primary lesion at inoculation; a rash is typical of secondary syphilis; an ulcer is a general description and not specific to the tertiary stage.