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Eric K. Oermann, Nicholas D. Coppa, Marc Margolis and Faheem A. Sandhu

Extramedullary hematopoiesis secondary to chronic anemia is well reported throughout the literature. A rare presentation of this condition is in the central nervous tissue reported most frequently as an epidural mass causing spinal cord compression. The authors report the case of a 51-year-old man with β-thalassemia and chronic anemia who was found to have a 4-cm paravertebral mass suggestive of a schwannoma. The patient underwent transthoracic resection of the mass. Histological examination confirmed an extramedullary hematopoietic tumor. In this article the authors propose a method to distinguish extramedullary hematopoietic tumors from schwannomas. To the authors' knowledge, this is the first reported case in the neurosurgical literature of this phenomenon.

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Eric K. Oermann, Marie-Adele S. Kress, Jonathan V. Todd, Brian T. Collins, Riane Hoffman, Huma Chaudhry, Sean P. Collins, David Morris and Matthew G. Ewend


Experience with whole-brain radiation therapy for metastatic tumors in the brain has identified a subset of tumors that exhibit decreased local control with fractionated regimens and are thus termed radioresistant. With the advent of frameless radiosurgery, fractionated radiosurgery (2–5 fractions) is being used increasingly for metastatic tumors deemed too large or too close to crucial structures to be treated in a single session. The authors retrospectively reviewed metastatic brain tumors treated at 2 centers to analyze the dependency of local control rates on tumor radiobiology and dose fractionation.


The medical records of 214 patients from 2 institutions with radiation-naive metastatic tumors in the brain treated with radiosurgery given either as a single dose or in 2–5 fractions were analyzed retrospectively. The authors compared the local control rates of the radiosensitive with the radioresistant tumors after either single-fraction or fractionated radiosurgery.


There was no difference in local tumor control rates in patients receiving single-fraction radiosurgery between radioresistant and radiosensitive tumors (p = 0.69). However, after fractionated radiosurgery, treatment for radioresistant tumors failed at a higher rate than for radiosensitive tumors with an OR of 5.37 (95% CI 3.83–6.91, p = 0.032).


Single-fraction radiosurgery is equally effective in the treatment of radioresistant and radiosensitive metastatic tumors in the brain. However, fractionated stereotactic radiosurgery is less effective in radioresistant tumor subtypes. The authors recommend that radioresistant tumors be treated in a single fraction when possible and techniques for facilitating single-fraction treatment or dose escalation be considered for larger radioresistant lesions.