Seborrheic keratosis is a benign epidermal proliferation that can be observed in whole body except from fingers, palms, and mucosa (except from a case with SK located in conjunctiva reported in the literature) [1].

Seborrheic keratosis is rarely located in the genital region. The cases with genital region localization include a relatively younger age group rather than the cases with classic localization [2,3]. The reason for genital located SK has not been known. In different literatures, because HPV 2 and 3 like particles have not been encountered in nucleus of keratinocytes in a little part of the SK samples analyzed in electron-microscope, HPV has been blamed in etiology. Moreover, chronic friction was also blamed in the etiology. Genital HPV positivity at varying rates in genital and extra-genital located SK’s have been reported [4,5].

Genital located SK is a rarely encountered case. And it is generally misdiagnosed as genital wart. In such cases histopathology is beneficial to confirm the diagnosis. Here we reported a rare genital located SK case that has been misdiagnosed as condyloma acuminate case. In our case, the diagnosis of SK was confirmed through the histopathology and dermoscopy.

A 35-year-old man was presented with a large verrucous growth on the pubic area and penis of 10 years duration. The lesion started as a small pigmented verrucous papul on the pubic area, which slowly increased in size to become a large verrucous mass and in extent to involve the entire external genitalia. On physical examination, a large, pigmented few verrucous masses (of size around 4 × 4 cm, 2 × 2 cm) and small pigmented verrucous papulas were seen in the external genitalia involving both penis and mons pubis (Figure 1). We considered differential diagnosis of condyloma acuminata, Buschke Lowenstein, verrucous carsinom and giant SK. Dermoscopic examination was carried out, which showed cerebriform appearance, fissures, ridges, and comedo-like openings consistent with SK. The histopathologic examination of a biopsy sample showed acanthosis that include basaloid cell proliferation consisting of thick keratohyalin granules and a keratinized obturator structures (Figure 2). HPV was determined on biopsy material through the PCR method. In performed HPV typing, HPV6 and HPV16, HPV6 as the dominant, were determined.

Figure 1: A large, pigmented few verrucous masses and small pigmented verrucous papules in the external genitalia involving both penis and mons pubis.

Figure 2: Biopsy sample showing acanthosis.

SK is frequently is a vesicant sharply circumscribed benign epidermal proliferation in round or oval shape in a color varying from skin tone to black. Genital located SK is rarely encountered [2,6,7].

HPV has been blamed in etiology. In a study carried out by Tardio et al. in order to clarify contribution of HPV upon the pathogenesis with a group including 40 genital SK and 20 extra-genital SK patients, HPV was not found in 28 (70%) of 40 genital SK samples [3]. HPV 6 was determined in 2 (10%) of 20 extra-genital SK samples. This study supported the relationship between HPV and genital SK. Unlike this study, there have been studies supporting that HPV was not determined in seborrheic keratosis in genital region and had no role upon the pathogenesis in the literature.8 In a study carried out by Serarslan et al. HPV DNA was not found in none of 12 SK samples in the paraffinembedded blocks [9]. In our case, we determined HPV6 and HPV16, HPV6 as the dominant. In a normal healthy human skin, HPV can be found as a part of microbiologic flora [10]. For this reason, determining HPV in skin tumor biopsies can only depend upon the contamination. Consequently, role of HPV on genital SK development has not recently been clarified exactly.

Another reason that can cause complexity in diagnosis apart from determining simultaneous HPV in seborrheic keratosis in genital region is seborrheic keratosis’ much similarity to condylomas histopathologically [11]. Some authors have approved the HPV existence in anogenital SKs and suggested that necessary histopathologic criteria are inadequate for SK diagnosis. Indeed, histopathologic diagnosis criteria of condyloma accuminata and diagnosis criteria of SK reported in dermatology, dermatopathology and pathology textbooks show great similarities [5].

In our case, HPV growth is a finding supporting the role of HPV in etiology. Consequently, we believe that genital region located seborrheic keratosis can be mistaken for condylomas clinically and histopathologically, HPV should be simultaneously researched for seborrheic keratosis determined in the genital region and dermoscopy should also be performed in addition to histopathology in order to confirm the diagnosis. Moreover, we consider that further studies are needed on etiopathogenesis in seborrheic keratosis.