Scalp Seeding Post Craniotomy and Radiosurgery for Solitary Brain Metastasis: A Case Report and Systematic Review

BACKGROUND   Radiosurgery is being increasingly used post craniotomy for brain metastasis, instead of whole-brain radiation. We report a case of scalp metastasis following craniotomy and radiosurgery, along with a systematic review of the literature. METHODS         Our patient was a 70-year-old male who presented with a scalp metastasis, two years after craniotomy and radiosurgery, for a solitary brain metastasis from esophageal carcinoma. Using Medline® (United States National Library of Medicine, Bethesda, MD), we performed a systematic review of the literature to identify cases of isolated scalp metastases following craniotomy for brain lesions. RESULTS           The scalp metastasis was in close proximity to the craniotomy site. Workup did not show any other site of active disease. Biopsy confirmed it to be a metastasis from esophageal carcinoma. The literature review did not yield any case of isolated scalp metastasis following craniotomy and whole-brain radiotherapy or radiosurgery. However, it yielded six cases of isolated scalp metastases following craniotomy for primary brain tumors. CONCLUSION     Isolated scalp metastasis has not been reported following craniotomy and whole-brain radiotherapy for brain metastases. Our patient likely had surgical seeding during craniotomy. These surgically implanted cells could not be ablated because the radiosurgery treatment volume does not cover the surgical tract. Further research is needed to identify risk factors for surgical seeding.