Introduction:

Discussion:

First described by Burkley in 1842 [2], naevus spills (NS) is characterized by a café-au-lait spot overlaid with more pigmented macules or papules. Histologically, it corresponds to lentiginous melanocytic hyperplasia with basal pigmentation, overlaid by a naevocellular nevus. Based on their size, three types are distinguished, similar to congenital nevi [3]: small NS (<1.5 cm), medium-sized NS (1.5-19.9 cm), and giant NS (>20 cm). Depending on their topography, a zosteriform type can also be identified, following a dermatomal distribution. Beyond classification by size and topography, Happle delineated two specific types of nevus spilus. The nevus spilus maculosus is a flat lesion featuring dark brown spots over a light brown base. Histologically, this type shows that the underlying pigmentation results from hyperpigmentation in the basal keratinocytes, while the darker spots are attributed to junctional melanocytes organized in nests [4,5]. In contrast, the papular nevus spilus is characterized by dark brown papules or nodules on a light brown background, which may also contain small dark spots. Histopathological examination of this type reveals characteristics of both superficial and deep congenital nevi, with the presence of melanocytes located in both the papillary and reticular dermis [4].

Since its discovery, this lesion has been widely debated, particularly for the possible occurrence of melanoma within the lesion. The first case of degeneration into melanoma was described by Perkinson in 1957 [6]. The precise risk of malignant transformation in NS is not well-defined, but it is believed to be between 0.13% and 0.2%. In cases where melanoma develops, its prognosis and management are similar to those of other types of melanoma. The risk of malignant degeneration within nevi is estimated to range from 0.13% to 0.2%.Nevi acquired in early childhood or congenital nevi, particularly those of the macular type and larger than 4 cm, especially giant and zosteriform variants, appear to be linked to an increased risk [7]. Additionally, the presence of dysplasia in the histology of a nevus constitutes a risk factor for malignant degeneration [7]. Melanoma manifests in approximately 60% of cases on small or medium-sized nevi, with 24% arising on zosteriform nevi and 16% on giant nevi [8,9]. An analysis of the existing literature reveals that the majority of cases involving malignant transformation predominantly occurred in Caucasian and Black patients. These cases had an average age of diagnosis at 49 years, with a female predominance and were more commonly located on the trunk (64%) compared to the limbs (36%) [10]. Melanoma associated with nevi generally manifested as a single tumor; however, there have been reports of multiple melanomas developing from the same nevus in some previous cases. Among the various subtypes, superficial spreading melanoma was the most commonly identified, accounting for 68%, while nodular melanoma and in situ melanoma each represented 16% [7, 8].

At present, there is no standardized method for the management of nevus spilus (NS). It is recommended that patients perform regular self-examinations to detect any changes in their nevi, in conjunction with a structured long-term follow-up that includes dermoscopy or, when available, confocal microscopy [7, 11, 12, 13]. This approach, combined with prudent biopsy of any concerning lesions, could enhance the early detection of melanoma. The literature does not support prophylactic excision of NS in the absence of histological confirmation of dysplasia or malignancy [7]. Conversely, in situations involving dysplasia or malignant melanoma, complete excision of NS is warranted [7, 10].

Due to the location of the lesion in a concealed area of the body, which was inaccessible to visual examination, our patient unfortunately could not detect any changes in her nevus and consequently sought medical advice too late, at a stage of metastasis.

Conclusion:

To clarify the biological behavior of NS and to develop standardized management guidelines, additional research is essential. Enhanced awareness and regular monitoring are vital for early detection and improved outcomes in patients with nevus spilus, particularly those with congenital variants.

Patient Consent Verbal informed consent was obtained from the patient for publication of this case report and accompanying images.

Conflict of Interest

The authors declare no conflict of interest.

Funding

The authors received no financial support for the research, authorship, or publication of this article.