Scalp Metastasis of Anaplastic Oligodendroglioma

Background Scalp metastases from anaplastic oligodendroglioma (AO) are extremely rare and mostly involve intracranial recurrence or widely metastatic disease. Here we describe an exceptional case of histopathologically proven scalp metastasis of AO 6 years after surgical resection and postoperative adjuvant radiation. Case Description A 42-year-old woman presented with several months of progressive headache and dizziness. Preoperative magnetic resonance imaging (MRI) showed an irregular enhancing lesion in the left frontal lobe extending to the ependymal surface. Left frontal craniotomy was performed through a coronal approach, and gross total resection was achieved. Pathologic examination confirmed a World Health Organization grade III AO. The patient subsequently received 60 Gy of external beam radiotherapy in 30 fractions over 6 weeks. During 8 years of follow-up, the patient remained symptom free, and no evidence of intracranial recurrence was found. However, 6 years after intracranial tumor resection, the patient noticed a subcutaneous mass in her right frontal scalp, which was the site contralateral to her craniotomy. MRI revealed a homogeneously marked enhancing nodular lesion in the subcutaneous tissue of the right frontal scalp without intracranial recurrence. Gross total resection was performed, and the pathologic findings, which identified the mass as an AO, were consistent with those of the primary left frontal tumor. Conclusions This study presents a rare case of long-term AO scalp metastasis without intracranial recurrence. Intraoperative seeding and longer survival for oligodendroglial tumors may cause this rare entity. Optimal surgical strategies and standard operative procedures can promote the prevention of iatrogenic seeding.