A rapidly growing perianal nodule associated with diffuse hyperpigmentation in a neonate

A 1-month-old preterm female infant presented with a naevus spilus-like giant congenital melanocytic naevus and a large perianal nodule. Histopathological analysis revealed junctional melanocytic activity interspersed with vascular channels, confirming the benign nature of the lesion. Immunohistochemistry showed positivity for human melanoma black-45, S100 and SOX10 in naevus cells and CD31 in vascular channels. Magnetic resonance imaging and Doppler ultrasound revealed extensive vascularity within the nodule and soft tissue involvement of the perineum.