Malignant Subdural Hematoma Associated with High-Grade Meningioma

A 70-year-old man, who had previously undergone surgical resection of left parasagittal meningioma involving the middle third of the superior sagittal sinus (SSS) two times, presented with recurrence of the tumor. We performed removal of the tumor combined with SSS resection as Simpson grade II. After tumor removal, since a left dominant bilateral chronic subdural hematoma (CSDH) appeared, it was treated by burr hole surgery. However, because the CSDH rapidly and repeatedly recurred and eventually changed to acute subdural hematoma, elimination of the hematoma with craniotomy was accomplished. The patient unfortunately died of worsening of general condition despite aggressive treatment. Histopathology of brain autopsy showed invasion of anaplastic meningioma cells spreading to the whole outer membrane of the subdural hematoma. Subdural hematoma is less commonly associated with meningioma. Our case indicates the possibility that subdural hematoma associated with meningioma is formed by a different mechanism from those reported previously.

clinical history, such as head injury, antithrombotic therapy, coagulation disorders, and alcohol abuse. In addition, postoperative images revealed no signs of CSDH. The left subdural hematoma alone was treated by burr hole surgery, which was successful (►Fig. 2b). However, recurrence of CSDH occurred 5 days after surgery. Although a second burr hole evacuation of subdural hematoma was performed, a third evacuation was required owing to its rapid recurrence within 2 days after the second evacuation. Because CSDH eventually changed to acute subdural hematoma (►Fig. 2c), craniotomy was accomplished 10 days after the third hematoma evacuation (►Fig. 2d). The hematoma and outer membrane of the subdural hematoma were eliminated as much as possible. Furthermore, the dura mater within the craniotomy area was removed and replaced with artificial dura mater. Histopathological features of the outer membrane of the subdural hematoma showed anaplastic meningioma, WHO grade III. Unfortunately, the patient died of worsening of general condition despite aggressive treatment one and a half months since the onset of CSDH although the subdural hematoma had obviously not recurred. His brain was inves-tigated by autopsy after death. Histopathology of brain autopsy demonstrated invasion of anaplastic meningioma cells spreading to the whole outer membrane of the subdural hematoma (►Fig. 3).

Discussion
Numerous causative factors for recurrence of CSDH have been addressed including advanced age, antithrombotic medications, coagulopathy, and various neuroimaging features of hematoma. 1,2 Although subdural hematoma formation in meningioma is rare, several mechanisms have been proposed as follows 3,15,19 : (1) bleeding of the tumor into the subdural space, (2) rupture of abnormal vascular networks supplying the tumor in the subdural space, and (3) collapse of the subdural vessels due to compression of the tumor.
No correlation between the occurrence of subdural hematoma and the location or histological characteristics of meningioma has been described. 15,20 On the other hand, the malignant histological type has been reported with a high frequency in meningioma complicated with subdural hematoma. 15,20 Patil observed that a dural reaction of the meningioma formed the neomembrane similar to the outer membrane of CSDH despite neither subdural fluid collection nor blood clots. 21 Moreover, they noticed that tumor cells were not expressed in the neomembrane originating from the meningioma. 21 In our case, the outer membrane of the subdural hematoma was entirely infiltrated by meningioma cells. To the best of our knowledge, no previous report has mentioned similar findings to our case. Meningioma with malignant transformation is indicated to acquire hematogenous spread. 22 The outer membrane of CSDH is highly vascularized and enriched with numerous capillaries. 1 Invasion of meningioma cells might occur hematogenously to the outer membrane of CSDH. Otherwise, meningioma in our case might have had capsule-like growth along the dura as en plaque meningioma. Formation of subdural hematoma related to a malignant tumor is considered to be the result of capillary dilatation and rupture of the outer membrane via fine vessel obstruction by tumor cells. 23 In high-grade meningioma, vascular endothelial growth factor (VEGF) is expressed and involved in permeabilization of blood vessels as well as tumor angiogenesis and vasculogenesis. 24 VEGF is detected in the outer membrane of CSDH and has an association with expansion of hematoma and recurrent bleeding. 25 Therefore, disruption of vulnerable tumor vessels or the effect of VEGF may allow the outer membrane infiltrated by meningioma cells to exude the hematoma into the subdural space.
An effective treatment strategy for subdural hematoma associated with meningioma is the elimination of hematoma at the same time as removal of the tumor. 19,26 Early surgical intervention is advocated, especially in cases accompanying acute subdural hematoma. 20 Our case had rapid and repeated recurrence of subdural hematoma despite prompt evacuation of the hematoma, eventually leading to death. Removal of the outer membrane surrounding subdural hematoma is presently not regarded as important. 1 However, the prognosis of our patient might have been improved by early removal of not only the hematoma but also as much of the outer membrane as possible.
In the case of CSDH associated with meningioma, especially high-grade meningioma, histopathological features of the outer membrane of subdural hematoma should be investigated. The subdural hematoma needs to be treated with caution when tumor infiltration is demonstrated in the outer membrane.

Conflicts of Interest
None.