A 17-Year-Old Male Adolescent With a Giant Isolated Scalp Neurofibroma Associated With a Calvarial Defect: A Case Report.

BACKGROUND Scalp neurofibromas are uncommon benign peripheral nerve sheath tumors and are typically associated with neurofibromatosis type 1 (NF1). Isolated scalp neurofibromas without NF1 findings are extremely rare, and large lesions with associated calvarial remodeling are even more exceptional. This study presents a giant occipital neurofibroma in a young patient without any diagnostic criteria of NF1 and discusses its clinical, radiological, surgical, and histopathological features in the context of current literature. CASE REPORT A 17-year-old male patient presented to our clinic with a gradually enlarging swelling in the left occipital region. Imaging studies revealed a well-circumscribed subcutaneous mass measuring 85×67 mm, associated with a 1-cm focal calvarial defect. Total surgical excision was achieved without the need for reconstruction. Histopathological evaluation confirmed a benign neurofibroma, scattered S-100 and SOX-10 positivity, a CD34-rich stromal network, and a Ki-67 index below 1%. No clinical or ophthalmologic findings suggestive of NF1 were detected. The postoperative course was uneventful, and no recurrence was observed at the 1-year follow-up. CONCLUSIONS This case represents a rare example of a large, isolated scalp neurofibroma occurring without NF1. The associated calvarial defect likely resulted from chronic pressure exerted by the slowly expanding lesion rather than invasive behavior. Complete surgical excision provided excellent cosmetic and clinical outcomes. Although malignant transformation risk is very low in solitary neurofibromas, long-term follow-up is recommended, especially for large lesions with bony involvement. This case contributes valuable insight into the diagnosis, management, and prognosis of isolated scalp neurofibromas.