Giant pigmented hairy nevus: clinical and histopathological 3-year follow-up after removal with 1,064 nm Q-Switched Nd:YAG Laser

Received on: 11 December 2011
Approved on: 6 July 2012
This study was carried out at the
Department of Dermatologic, Infectious and
Parasitic Diseases of the Faculdade de
Medicina de São José do Rio Preto (Famerp)
– São José do Rio Preto (SP), Brazil.
Financial support: None
Conflict of interest: None

Abstract

Giant congenital melanocytic nevi are extremely rare, however there is a 5-10% chance they will develop into melanomas. Laser-based treatment of this type of lesion is still very controversial. Some studies report great success without malignant development and others have achieved good aesthetic results but with malignancy. This article describes the clinical and histological development of a case of a female patient with a giant congenital melanocytic bathing trunk nevus, after 14 sessions of 1,064 nm Q-Switched Nd:YAG laser and three years of follow-up without histological signs of malignancy. The authors highlight the need for histological monitoring of this type of lesions.

Keywords: NEVUS, NEVUS, PIGMENTED, LASER THERAPY

INTRODUCTION

Congenital melanocytic nevi are potentially malignant lesions that are either present at birth or develop during childhood from pre-existing nevus cells.1 Giant congenital melanocytic nevi (GCMN) are extremely rare, with an estimated incidence of one in every 20,000 births, but have a 5-10% risk of developing melanoma. They are longer than 20cm along the longest axis, have an area of 100cm2, or cover at least 2% of the total area of the body. Since they can cover large skin surfaces and assume the shape of pieces of clothing, they are sometimes called GCMN in bathing trunks, cap, or cape.

Treatment of those lesions is based on two principles: limiting the risk of malignant transformation and promoting an acceptable cosmetic result. Decades ago, before laser was used in dermatological practice, many lesions were untreatable, since most GCMNs are inoperable.2 Currently, laser treatment is seen as a good option for treating such pigmented lesions. This article describes the use of a1,064 nm Q-switched Nd:YAG laser in the treatment of a ''''''''bathing trunk'''''''' GCMN in a female patient. The study was approved by the Ethics and Research Committee of the Faculdade de Medicina de São José do Rio Preto.

CASE REPORT

A 23-year-old female patient, Fitzpatrick skin type III, who was born with a giant hairy melanocytic lesion sought care at the Dermatology Outpatient Clinic of the Faculdade de Medicina de São José do Rio Preto, São Paulo, Brazil. At approximately 30x20cm in diameter, the lesion affected the lower third of the back and the whole posterior hip and infragluteal region, totaling more than 13.5% of the body surface area (Figure 1). The lesion considerably affected the patient''''''''s quality of life. Serial dermoscopic assessments, clinical follow-ups, and biopsies of the affected area were proposed in order to monitor the lesion and detect malignization areas early on. All histopathological results suggested an intradermal melanocytic nevus with no malignancy (Figures 2A and 2B). After a five-year follow- up, the patient underwent treatment with 1,064nm QSwitched Nd:YAG laser (Q YAG5 – Palomar Medical Technologies, Burlington, MA, USA).Local anesthesia was applied around the treated area with anesthetic solution (2% lidocaine with epinephrine diluted in equal parts with 0.9% saline solution). Next, the authors applied the 1,064nm Q-switched Nd:YAG laser at 10Hz frequency, 2mm spot size, and 6.5- 12.5 J/cm2 fluence. Fourteen sessions were held at one-month intervals (Figures 3, 4 and 5). The authors also conducted three diode laser sessions (Light Sheer), with 30J of energy and a frequency of 30ms, to remove hairs on the GCMN. The lesion was followed up for 36 months, and various histological analyses were carried out during that period – all of which resulted in a diagnosis of intradermal melanocytic nevus without hyperplasia or atypia. The microscopic comparison of specimens before and after treatment demonstrated a decreased amount of nevus cells and intradermal melanocytes after the laser treatment (Figure 6).

DISCUSSION

GCMN are located in the lower two-thirds of the dermis, occasionally extending to the subcutaneous layer of individual nevus cells distributed among collagen fibers; are associated with skin appendages, nerves, and vessels within the reticular dermis; and have a greater average thickness than acquired melanocytic nevi.3 The choice of treatment for congenital melanocytic nevi should consider the location, depth, and clinical appearance of the lesion, the risk of developing melanoma, and the aesthetic and psychological factors involved. There are several treatment options such as surgical excision, dermabrasion, curettage, cryosurgery, chemical peeling, and laser therapy.4 Laser treatment was chosen in the present case due to the lesion''''''''s dimensions and its impact on the patient''''''''s quality of life.

The treatment of GCMNs using laser is still very controversial, with some reports of great success without malignization and some of aesthetic success but with malignization.5,6 In addition, the incomplete removal of nevus cells, especially deeper ones, does not fully eliminate the risk of emergence of melanoma. Furthermore, decreasing the lesion''''''''s pigmentation can hamper the early detection of color changes that indicate malignancy in the deeper layers of the GCMN.7 The authors understand that GCMNs can become malignant even without any laserbased intervention; they deemed it more important to improve the patient''''''''s quality life and carefully monitor the lesion''''''''s development through dermoscopy and biopsy.7

Non-ablative laser methods appear to offer advantages over ablative methods – such as the CO2 laser –in the treatment of GCMN. The authors chose the 1,064nm Q-Switched Nd:YAG laser since it is one of the most selective regarding the melanocytes chromophores, in addition to its deeper penetration in the dermis and the existence of several published scientific reports regarding its safety and patients'''''''' improved quality of life.5 In the present study''''''''s clinical follow-up, a partial whitening of the treated area was observed, indicating the difficulty in treating GCMN. Nevertheless, in the serial histopathological three-year follow-up, no signs of malignancy were found. The authors highlight the crucial importance of continually monitoring GCMN patients treated with laser.

References

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2 . Michel JL. Laser therapy of giant congenital melanocytic nevi. Eur J Dermatol. 2003;13(1):57-64

3 . Tokuda Y, Saida T. Histogenesis of congenital and acquired melanocytic nevi based on histological study of lesion size and thickness. J Dermatol. 2010; 37(12):1011-8

4 . Jones CE, Nouri K. Laser treatment for pigmented lesions: a review Cosmet Dermatol. 2006;5(1):9-13

5 . Bukvic Mokos Z, Lipozencic J, Ceovic R, Stulhofer Buzina D, Kostovic K. Laser therapy of pigmented lesions: pro and contra. Acta Dermatovenerol Croat 2010; 18(3): 185-9

6 . Hague JS, Lanigan SW. Laser treatment of pigmented lesions in clinical practice: a retrospective case series and patient satisfaction survey. Clin Exp Dermatol. 2007;33(2): 139-41

7 . Marghoob AA, Borrego JP, Halpern AC. Congenital Melanocytic Nevi: Treatment Modalities and Management Options. Semin Cutan Med Surg 2003; 22(1): 21-32