What is your diagnosis?

Figures 1-3 Newborn on the first day of life with a homogeneous, brown, hyperpigmented macula more than 15 cm in diameter on the right upper limb and thoracic region. 

Discussion

After diagnosis, the newborn was discharged with indication for Neonatology and Dermatology follow-up. On reassessment, he showed adequate psychomotor growth and development, an unremarkable neurological examination, and no areas of concern on routine dermoscopy. Subsequent evaluation with cranioencephalic magnetic resonance imaging (MRI) at 14 months of age was normal.

CMN is a benign proliferation of neural crest-derived melanocytes that form theca or nests at the dermal-epidermal junction and/or in the dermis.¹⁾ Brown in color, it may be present from birth or appear during the first two years of life at any body surface area.^1,2 Based on adult size projection, CMN are classified as small (<1.5 cm), medium (1.5-20 cm), large (20-40 cm), giant (>40 cm), or multiple.³ Compared to other CMN, giant CMN is a rare entity, with an incidence of 1:20,000 newborns, and has a higher and earlier risk for melanoma (6-20%).^1,2,4,5 Melanomas arising from congenital nevi are rarer than spitzoid melanomas, but account for most melanoma-related deaths in childhood.⁵⁾

Management of CMN should be based on age, nevus size, and other factors such as psychosocial impact, association with vascular malformations, limb atrophy and asymmetry, neurocutaneous melanosis, and characteristic facial morphology.^1,2,4,6) Given the potential for malignancy, giant CMN require clinical surveillance with neurodevelopmental follow-up, regular dermoscopy, and early surgical intervention (excision or biopsy) of suspicious lesions for timely diagnosis of melanoma.^2,4-6 Surveillance with digital dermoscopy has optimized early diagnosis of melanoma and reduced the number of unnecessary excisions. Thus, in lesions considered atypical but with low suspicion of melanoma, dermoscopic surveillance may be preferred to surgery.^2,4) A spectrum of central nervous system abnormalities has been described in association with congenital melanocytic naevi.⁶⁾ In this context, cranioencephalic MRI should be performed for early detection of melanin deposition, especially in the temporal lobes, cerebellum, pons, and/or medulla, in neurologically asymptomatic patients with giant CMN.^6,7 If cranioencephalic MRI shows no changes, it should be repeated only if suspicious symptoms arise.^5,7

Authorship

Ana Gisela Oliveira - Bibliographical search; clinical case conception and design; Data curation; Formal analysis; Writing - original draft; Writing - review & editing; Validation

João Marques - Bibliographical search; Methodology; Data curation; Writing - original draft; Writing - review & editing; Validation

Joaquina Antunes - Bibliographical search; Methodology; Writing - original draft; Writing - review & editing; Validation

Pedro Maneira Sousa - Bibliographical search; Methodology; Writing - original draft; Writing - review & editing; Validation

Rita Cabral - Bibliographical search; Methodology; Writing - original draft; Writing - review & editing; Validation

Isabel Andrade - Bibliographical search; Methodology; Writing - original draft; Writing - review & editing; Validation