Mimicking the malignant: Solitary nevus lipomatosus cutaneous superficialis with vascular malformation

Nevus lipomatosus cutaneous superficialis (NLCS) is a rare, benign hamartomatous dermal lesion characterized by ectopic mature adipocytes within the dermis. Although typically asymptomatic and localized, atypical variants can pose diagnostic dilemmas. We report a 16-year-old male presenting with a gradually enlarging, bluish, non-compressible left flank lesion. Imaging suggested a vascular or soft-tissue neoplasm. Histopathological evaluation of the excised specimen revealed mature adipocytes interspersed with dilated vascular channels in the dermis, confirming NLCS with a coexisting vascular malformation. NLCS most often occurs in childhood or early adulthood, either as classical multiple plaques or a solitary nodule. Rare associations, such as vascular malformations, can mimic malignant tumors and confound diagnosis. Histopathology remains the gold standard for confirmation. This case highlights an unusual presentation of solitary NLCS with vascular malformation, underscoring the importance of histological evaluation and documentation of rare morphological variants to avoid overtreatment.