Histopathologic and immunohistochemical distinction of condyloma and seborrheic keratosis in the genitofemoral area

Background: Making a clinical and histological distinction between condyloma and seborrheic keratosis in the genitofemoral area can be difficult. This study aimed to find reliable histological and immunohistological criteria to diagnose these entities. Methods: We retrospectively studied genitofemoral skin biopsy specimens obtained between January 2004 and December 2007 that had been diagnosed as showing condyloma or seborrheic keratosis. The histological findings were assessed and immunohistochemical stains were performed for human papillomavirus, Ki-67, and p21. DNA was extracted from paraffin sections and amplified by polymerase chain reaction to detect the presence and type of human papillomavirus. Results: DNA extractionwas successfully performed for 58 lesions. The final diagnoses were condyloma in 41 and seborrheic keratosis in 17. The diagnosis of condyloma rather than seborrheic keratosis was likely in the presence of broad, evenly distributed reticulated acanthosis (p< 0.0001), koilocytosis (p< 0.001), a fascicular arrangement of keratinocytes (p< 0.01), and an absence of horn cysts (p< 0.01). Immunohistochemical staining supported the diagnosis of condyloma when positive for human papillomavirus (p< 0.0001), Ki-67 (p< 0.0001), and p21 (p< 0.0001). Conclusion: A combination of histological and immunohistochemical findings is useful to distinguish condyloma from seborrheic keratosis in the genitofemoral area. Copyright 2012, Taiwanese Dermatological Association. Published by Elsevier Taiwan LLC. All rights reserved.