Congenital Cutaneous Neurocristic Hamartoma of the Scalp with Poor Melanin Content

Cutaneous neurocristic hamartoma (CNH) is a rare tumor that arises from cells of neural crest origin. This tumor typically proliferates within the dermis or subcutaneous adipose tissue and usually exhibits pigmentation, which requires differentiation from conditions such as blue nevus and congenital nevus. We report CNH in a 5-month-old female infant. A subcutaneous mass in the parietal region was identified 4 days after birth. Imaging studies revealed that the subcutaneous mass was approximately 7 cm in diameter and involved the intracranial space. An open biopsy specimen obtained at 3 months of age suggested a benign hemangiopericytomatous tumor, and tumor excision was subsequently performed at 5 months of age. Histologically, the lesion was characterized by a mixture of nevoid epithelioid and spindle-shaped fibroblast-like cells. Melanin-pigmented melanocytes were observed in only a small portion of the lesion. Immunohistochemically, the epithelioid cells were positive for S100 protein, SOX10, human melanin black 45 (HMB45) (PMEL), and melan-A (MLANA), whereas the spindle-shaped cells were positive for CD34. Based on the histological and immunohistochemical findings, a diagnosis of CNH was made. An accurate diagnosis and long-term follow-up are mandatory in CNH due to the potential for malignant transformation, including transformation to melanoma.