Distinction of Condylomata Acuminata From Vulvar Vestibular Papules or Pearly Penile Papules Using Ki-67 Immunostaining

Abstract

Background: Ki-67 is an immunohistochemical stain used as a nuclear proliferation marker. It is nonspecific, and is expressed in all active phases of the cell cycle. Vulvar vestibular papules in women and pearly penile papules in men are benign fibrous papules on the genitals, are noninfectious, and do not require treatment. However, these lesions can be clinically confused with condylomata acuminata induced by human papillomavirus (HPV), which have medical and social implications. Objective: Because HPV infection is known to induce expression of proliferation markers, we propose that Ki-67 be used to differentiate condylomata acuminata from vulvar vestibular papules or pearly penile papules on pathologic examination. Methods: We reviewed a total of 26 lesions from 18 patients of previously pathologically diagnosed lesions, including condylomata acuminata (11 lesions), vulvar vestibular papules (10 lesions), and pearly penile papules (5 lesions). All slides were stained with Ki-67, reviewed, and categorized as positive or negative for Ki-67 staining by 1 investigator who was unaware of the original diagnosis. Results: Eleven out of 11 cases of condylomata acuminata were identified as positive for Ki-67 staining. Ten out of 10 cases of vulvar vestibular papules were negative for Ki-67. Five out of 5 cases of pearly penile papules were negative for Ki-67. Conclusion: Ki-67 is a reliable marker to pathologically distinguish benign vulvar vestibular papules in women, or pearly penile papules in men, from HPV-induced condylomata acuminata.