Vulvar melanocytic nevus: case report

ABSTRACT

Pigmented vulvar lesions are uncommon; they occur in about 10%-12% of women and include benign and malignant processes, as well as post-inflammatory changes and hyperchromatic lesions due to melanin increase. Among the benign processes, there are vulvar nevi, present in 2% of adult women. There is a small subgroup classified as atypical melanocytic nevi that account for 5% of vulvar nevi and is associated with younger women. Despite the importance of early diagnosis, the clinical history and time of evolution of the lesion are not well explored, as patients rarely examine the region, as do dermatologists. We report a case of an melanocytic nevus in the small lip in a 43-year-old woman.

Key words:
pigmented nevus; vulva; pathology

RESUMEN

Las lesiones pigmentadas de la vulva son poco frecuentes; ocurren entre el 10% y el 12% en mujeres y abarcan procesos benignos y malignos, así como cambios post-inflamatorios y máculas hipercrómicas debido al aumento de la melanina. Entre los procesos benignos, hay nevos vulvares, presentes en el 2% de las mujeres adultas. Hay un pequeño subgrupo formado por nevos melanocíticos atípicos, que representan el 5% de los nevos vulvares y ocurren en mujeres más jóvenes. A pesar de la importancia del diagnóstico temprano, la historia clínica y el tiempo de evolución de la lesión no son muy explotados, pues las pacientes rara vez examinan la región, así como los dermatólogos. Presentamos un caso de nevo melanocítico en labio menor de una mujer de 43 años de edad.

Palabras clave:
nevo pigmentado; vulva; patología

RESUMO

As lesões pigmentadas de vulva são incomuns; ocorrem entre 10% e 12% nas mulheres e abrangem processos benignos e malignos, bem como alterações pós-inflamatórias e lesões hipercrômicas devido ao aumento de melanina. Entre os processos benignos, há os nevos vulvares, presentes em 2% das mulheres adultas. Existe um pequeno subgrupo classificado como nevos melanocíticos atípicos, que representa 5% dos nevos vulvares e está associado a mulheres mais jovens. Apesar da importância do diagnóstico precoce, a história clínica e o tempo de evolução da lesão não são muito explorados, pois as pacientes raramente examinam a região, assim como os dermatologistas. Apresentamos um caso de nevo melanocítico em pequeno lábio em uma mulher de 43 anos.

Unitermos:
nevo pigmentado; vulva; patologia

INTRODUCTION

Vulvar pigmented lesions are uncommon, occurring in about 10% to 12% of women and include benign and malignant processes, as well as post-inflammatory changes and hyperchromatic lesions due to increased melanin. Among the benign processes are vulvar nevi, which are usually present in 2% of adult women. A small subgroup, classified as atypical melanocytic nevi, represents 5% of vulvar nevi and is associated with younger age. Despite the importance of early diagnosis, the clinical history and time of evolution of the lesion are not well explored, as patients rarely examine the region, as do dermatologists. We present a case of an melanocytic nevus located on the small lip of a 43-year-old woman.

CASE REPORT

A 43-year-old female patient underwent an excisional biopsy of a whitish-brown lesion on her right small lip. The fragments were submitted to anatomopathological examination. Macroscopy revealed two irregular fragments of whitish-brown and an elastic tissue were reported, together measuring, 0.4 × 0.4 × 0.2 cm. On microscopy, hematoxylin and eosin-stained (HE) sections indicated a fragment of squamous mucosa covered by epithelium with preserved morphology. In the lamina propria, nevus cells were observed arranged in nests and cords with the presence of few lymphocytes. There was no sign of malignancy in the material examined. This scenario led us to the diagnosis of melanocytic nevus in the right lip region (Figures 1 and 2).

FIGURE 1
Vulvar melanocytic nevus; HE, 40×

FIGURE 2
Vulvar melanocytic nevus; HE, 100×

DISCUSSION

Pigmented vulvar lesions occur in about 10% to 12% of women, and their differential diagnoses include benign and malignant lesions, such as nevi and melanomas, as well as nonproliferative entities¹. Seborrheic keratosis, vulvar intraepithelial neoplasia (VIN), and squamous cell carcinoma (SCC) are important differential diagnoses. Another differential diagnosis to be considered is vulvar melanosis, which occurs mainly in white women and its origin is unknown - a disturbance of melanin transfer to epidermal keratinocyte or chronic stimulus has been considered as a possible etiology. Despite its benign behavior, vulvar melanosis is a cause of concern, since its clinical aspect resembles mucosal melanoma (multiple irregular and pigmented macules), more common in older women. Within the diagnosis of vulvar melanosis, approximately 2% of women present nevi in the same location². A subtype classified as atypical vulvar melanocytic nevus accounts for about 5% of these nevi and usually manifests itself in young women aged between 17 and 26 years, while the common nevus tends to appear through postmenopause³. In such cases, excisional biopsy is usually sufficient. The patient in this case is an exception, as she has a melanocytic nevus at an advanced age.

CONCLUSION

Because the location of the lesion is difficult to explore, both by the dermatologist and the patient, vulvar pigmented lesions may go unnoticed. Once diagnosed, the woman must undergo a biopsy to make a differential diagnosis with malignant lesions. The finding of vulvar melanocytic nevus in a 43-year-old patient makes the case atypical, since the age group is not compatible.

REFERENCES

• ¹
  Hosler GA, Moresi JM, Barrett TL. Naevi with site-related atypia: a review of melanocytic naevi with atypical histological features based on anatomic site. J Cutan Pathol. 2008; 35: 889-98.
• ²
  Ferrari A, Zalaudek I, Argenziano G, et al. Dermoscopy of pigmented lesions of the vulva: a retrospective morphological study. Dermatology. 2011; 222: 157-66.
• ³
  Rock B, Hood AF, Rock JA. Prospective study of vulvar nevi. J Am Acad Dermatol. 1990; 22: 104-6.

Publication Dates

• Publication in this collection
  01 July 2020
• Date of issue
  2020

History

• Received
  23 Oct 2019
• Reviewed
  29 Oct 2019
• Accepted
  29 Nov 2019
• Published
  06 Jan 2020