Which oral lesion associated with syphilis is known to be highly contagious?

Explanation

The mucous patch is a highly infectious oral lesion seen in secondary syphilis. Gummas are granulomatous lesions occurring in tertiary syphilis and are not contagious. Koplik spots are indicative of measles, not syphilis. Tabes dorsalis is a neurological complication of late syphilis, not an oral lesion.