Pigmented wart due to human papilloma virus type 60 showing parallel ridge pattern in dermoscopy

ARTICLE

Auteur(s) : Miki Tanioka¹, Yujin Nakagawa¹, Naoki Maruta¹, Gen Nakanishi²

¹Division of Dermatology, Fukui Red Cross Hospital, Fukui, 918-8507, Japan
²Department of Dermatology, Shiga University of Medical Science, Otsu, Japan

Dermoscopic examination is a recent advance in the diagnosis of palmoplanter pigmented lesions. Parallel-ridge pattern (PRP) is one of the most important dermoscopic findings, and is observed in macular portions of malignant melanoma on the acral volar skin [1]. The sensitivity and specificity of the PRP in detecting malignant melanoma was 86% and 99%, respectively [1]. Here, we present a pigmented wart on the sole with PRP in dermoscopy.

A 45-year-old man was referred to our department for evaluation of a pigmented macule on the right sole. His medical history was unremarkable. Physical examination revealed a pigmented macule on the right sole (figure 1A). The diameter was 11 millimeters. The macule showed color variegation and hyperkeratosis. Dermoscopic examination revealed waved hyperkeratosis and tiny dotted (pinpoint) vessels on a light brownish background (figure 1B). The pigmentation showed PRP. The finding of PRP strongly suggested that the lesions might be malignant melanoma, however there were no other dermoscopic signs, such as a fibrillar pattern. A skin biopsy from the macule revealed hyperkeratosis and acanthosis (figure 1C). Keratinocytes in the lesion contained eosinophilic cytoplasmic inclusions. No atypical melanocytic proliferation was observed. DNA was extracted from the biopsy specimens of the lesion. Polymerase chain reaction (PCR) amplification was performed with human papilloma virus type 60 specific primers [2] on extracted DNA and then amplified PCR products were confirmed by direct sequencing analysis (figure 1D). Therefore, we diagnosed the skin lesion as a pigmented wart due to human papilloma virus type 60, showing a parallel ridge pattern in dermoscopy.

In Japan, the incidence of malignant melanoma has increased strikingly. Compared with Caucasian patients with malignant melanoma where superficial spreading melanoma is the most frequent subtype (70%), acral lentiginous melanoma is the most prevalent clinical phenotype in non-white populations and accounts for about half of malignant melanoma in Japan. In addition, approximately half of Japanese acral lentiginous melanoma cases occur on the sole of the foot. Therefore, it is important to distinguish malignant melanoma from benign skin lesions when we examine a pigmented macule on the sole. In the present case, the patient was referred to our department, because a local doctor detected a PRP sign. However, we considered the macule on his sole as non-melanoma, because it showed hyperkeratosis with tiny dotted vessels on a brownish background, which is characteristic of a plane wart in dermoscopy [3].

PRP is a sign of melanoma, with the exception of benign pigmented macules, including anti-cancer drug-induced hyperpigmentation on the volar skin, pigmented macules on the fingers and toes of patients with Peutz-Jeghers syndrome, subcorneal hemorrhage with a dermoscopic feature named pebbles on the ridges, and an occupation-related pigmentation due to para-phenylenediamine [4]. Usually, the above-mentioned diseases are excluded by their typical medical and family histories.

The most important differential diagnosis in the present case is verrucous malignant melanoma. Verrucous malignant melanoma is a variant of malignant melanoma which may be confused with benign lesions. A report of 20 cases of verrucous malignant melanoma showed it occurred more often on the back and limbs of male patients with a mean age of 57 years [5]. In over 50% of the cases, benign lesions such as warty nevi, papillomas, seborrheic keratosis or cysts were made clinically. Also, in the present case, verrucous malignant melanoma was clinically suspected.

A previous paper reported that plantar warts due to human papillomavirus type 60 are predominantly pigmented when discovered after early adulthood [6]. In the present case, clinical features are compatible with the report and both pathology and molecular analysis confirmed the diagnosis.

Acknowledgements

References

2 Egawa K, Kitasato H, Honda Y, Kawai S, Mizushima Y, Ono T. Human papillomavirus 57 identified in a plantar epidermoid cyst. Br J Dermatol 1998; 138: 510-4.

3 Soyer P, Argenziano G, Ruocco V, Chimenti S. Dermoscopy of pigmented skin lesions. Eur J Dermatol 2001; 11: 483-98.

4 Tanioka M, Matsumura Y, Utani A, Tanaka M, Miyachi Y. Occupation-related pigmented macules on the sole with parallel-ridge pattern on dermoscopy. Clin Exp Dermatol 2009; 34: e31-e33.

5 Blessing K, Evans AT, Al-Nafussi A. Verrucous naevoid and keratotic malignant melanoma: a clinico-pathological study of 20 cases. Histopathology 1993; 23: 453-8.

6 Kashima M, Tanabe Y, Kaminishi K, et al. Human papillomavirus type 60 plantar warts are predominantly pigmented when discovered after early adulthood. Br J Dermatol 1999; 141: 601-3.