Nevus spilus (speckled lentiginous nevus) associated with a nodular neurotized nevus

Differentiating Neurotized Melanocytic Nevi From Neurofibromas Using Melan-A (MART-1) Immunohistochemical Stain

Context.—Neurotized melanocytic nevi and neurofibromas are common, benign cutaneous neoplasms. Usually they are histologically distinct from each other; however, neurotized melanocytic nevi and neurofibromas can be clinically and histologically similar.

Objective.—To determine whether Melan-A (MART-1) immunohistochemical stain is sufficient to differentiate neurotized melanocytic nevi from neurofibromas.

Design.—Forty-nine consecutive specimens of melanocytic nevi with neurotization and 49 specimens of neurofibromas were selected. We used antibodies against Melan-A, S100, and neurofilament protein.

Results.—All of the melanocytic nevi showed Melan-A staining within the neurotized areas, with most of the areas staining strongly positive, whereas all the neurofibromas were completely absent of Melan-A stain. All of the nevi, including the neurotized areas, stained strongly and diffusely for S100, whereas all the neurofibromas showed a distinctive, sharp, wavy pattern of S100 staining. Neurofilament protein showed scattered staining of both melanocytic nevi and neurofibromas.

Conclusions.—Our data indicate that Melan-A immunohistochemical staining is helpful in differentiating neurotized melanocytic nevi from neurofibromas when distinction on histomorphology alone is difficult.

Nevus Spilus and Melanoma: Case Report and Review of the Literature

Background:

Nevus spilus is characterized by a pigmented patch with scattered flat or maculopapular speckles. Nevus spilus was first described by Burkley in 1842. Since then, this lesion has been widely debated in the literature, particularly for the possible occurrence of melanoma within the lesion.

Objective:

We describe the case of a 65-year-old female presenting with a nodular achromic melanoma that occurred within a nevus spilus on the left thigh.

Conclusion:

Our observation is consistent with the idea that this entity in some circumstances may have the ability to evolve into a malignant melanoma.

Mélanome sur naevus spilus : 5 observations

BACKGROUND

Nevus spilus is defined as café-au-lait macules with dark maculopapular speckles. Histologically, it has the aspect of lentigo associated with nevocellular nevus. There are 3 types of nevus spilus: small or medium-sized (<20 cm), giant and zosteriform. Malignant transformation of nevus spilus is rare.

PATIENTS AND METHODS

We analyzed the cases of 5 patients presenting melanoma within nevus spilus as well as 20 published cases. The evaluation criteria were: for nevus spilus: size, type, topography, age of onset and presence of dysplastic nevi within the nevus spilus; for melanoma: clinical aspect, histological type, thickness, level and age at diagnosis. The presence of other risk factors for melanoma was noted.

RESULTS

The 14 women and 11 men had a mean age of 49 years at melanoma diagnosis. Type of nevus spilus was: small or medium-sized (15 cases), zosteriform (6 cases) and giant (4 cases). Only 3 nevi spili were<4 cm in diameter. Nevus spilus was present since birth (11 cases), childhood (7 cases), after the age of 20 years (3 cases) and was unspecified in 4 cases. Three of our five patients had other risk factors for melanoma. Two patients were presenting 2 melanomas within nevus spilus. The histological type of melanoma was not specified in 8 cases but SSM was the most common type (13 cases). Median Breslow thickness was 1.25 mm (0.27 to 8 mm) for the 19 cases in which it was specified.

CONCLUSION

The following criteria appeared to be associated with risk of developing melanoma in nevus spilus patients: nevus spilus present since birth, nevus spilus over 4 cm in diameter, and giant or zosteriform nevus spilus. Development of melanoma within nevus spilus is a rare event. Consequently, guidelines for follow-up of nevus spilus cannot be defined. However, follow-up is recommended, and in particular, self-examination.

Immunohistochemistry in diagnostic dermatopathology

This article briefly reviews many immunohistochemical stains that have been in use for years, emphasizing their diagnostic use and potential pitfalls. Several newer immunostains are described in a more comprehensive fashion, including brief summaries from recently published studies.