Divided nevus of the penis

ARTICLE

Auteur(s) : Cheng Zhou, Hongjun Xu, Dongjie Zang, Juan Du, Jianzhong Zhang

Department of Dermatology, Peking University People's Hospital, Beijing 100044, China

Divided nevus or kissing nevus of the penis is a rare entity originating during embryogenesis. The lesions locate on the glans penis and the inner surface of the prepuce, representing mirror-image symmetry relative to the coronal sulcus. We report three Chinese cases.

A 20-year-old man presented with melanocytic nevi on his penis. The pigmented lesions on the glans penis (19 × 16 mm) and on the inner surface of the prepuce (18 × 13 mm) on the right dorsum of the penis (figure 1A) appeared as mirror images of each other relative to the coronal sulcus when the skin of the prepuce was retracted. His family history was negative. Histological examination of the biopsy specimen taken from the prepuce revealed a compound nevus (figure 1D).

A 25-year-old man with a redundant prepuce complained of melanocytic nevi on his penis since the prepuce could be retracted in his teens. He found erythema on his penis with mild itching three days before his visit. Two pigmented lesions were located on both sides of the coronal sulcus, affecting the inner surface the prepuce (12 × 6 mm) and the left side of the glans next to the urinary meatus (12 × 10 mm) (figure 1B). Erythema with mild erosion was noticed around the coronary sulcus and the nevus on the prepuce, and balanoposthitis was diagnosed. After one week treatment of triamcinolone acetonide and econazole nitrate cream, the erythema and erosion improved, leaving the nevus as before.

A 21-year-old man presented with melanocytic nevi on thepenis involving both the inner surface of the prepuce (11 × 6 mm) and the right dorsum of the penis (11 × 8 mm) with mirror image symmetry (figure 1C). The lesions werenoticed after circumcision when he was 7 years old.

Divided nevus or “kissing” nevus was first described by Von Michael in 1908 [1], and named by Fuchs in 1919 [2], describing a congenital melanocytic nevus that occurs on adjacent parts of the upper and lower eyelids and may appear to be a single lesion when the eye is closed. Divided nevus of the penis is extremely rare, only eight cases have been described [2]. The divided nevus was located on the dorsal or dorsolateral aspect of the glans penis and the inner surface of the prepuce without involvement of the coronal sulcus [3]. Most lesions showed sharply-demarcated, oval-shaped, smooth-surfaced, pigmented macules, and presented mirror-image symmetry relative to the coronal sulcus [3, 4]. The histology mostly showed compound or intradermal melanocytic nevi [2, 3, 5].

Divided nevus occurs only on those parts of the body that separate during embryogenesis [5]. From the 11-14th gestational week, cleavage of the invaginated epithelial preputial placode divides the glans from the prepuce [3, 5]. It has been proposed that migration of melanoblasts occurs just after completion of the invagination of the preputial epithelial placode at the 12th week of gestation, preceding the embryological separation of epithelial preputial placode [3, 5]. Consequently, separate lesions of the penis may originate from a single lesion in the embryo that subsequently divides during maturation of external genitalia [3, 5]. This embryological separation results in mirror-image lesions relative to the coronal sulcus, with the same size and shape. Epithelial invagination from the dorsal side precedes the ventral side and may explain why the predilection site is almost always the dorsal or dorsolateral aspect [3].

Malignant melanoma of the penis is very rare, accounting for less than 2% of all primary malignancies of the penis [2]. Most arise in the sixth or seventh decade and precursor melanocytic nevi are not usually identified [6]. There are differing opinions regarding the management of melanocytic nevus of penis [6]. For divided nevus, only one patient underwent malignant alteration in the literature [2]. Most lesions were greater than 10 mm in diameter, and the esthetic challenges presented by lesion removal should be carefully considered. In our opinion, conservative care with close follow-up might be more appropriate.

Acknowledgements

References

2 Egberts F, Egberts JH, Schwarz T, Hauschild A. Kissing melanoma or kissing nevus of the penis? Urology 2007 ; 69 : 384 e385-7.

3 Kono T, Nozaki M, Kikuchi Y, Ercocen AR, Hayashi N, Chan HH, et al. Divided naevus of the penis: a hypothesis on the embryological mechanism of its development. Acta Derm Venereol 2003; 83: 155-6.

4 Choi GS, Won DH, Lee SJ, Lee JH, Kim YG. Divided naevus on the penis. Br J Dermatol 2000; 143: 1126-7.

5 Desruelles F, Lacour JP, Mantoux F, Ortonne JP. Divided nevus of the penis: an unusual location. Arch Dermatol 1998; 134: 879-80.

6 Mahto M, Woolley PD, Ashworth J. Pigmented penile macules. Int J STD AIDS 2004; 15: 717-9.