Multifocal thoracic intradural extramedullary anaplastic ependymoma: case report and review of the literature

Multifocal intradural and extramedullary anaplastic ependymoma of the spinal cord is a very rare anatomo-pathological entity.

From the literature, we find only 28 cases of intradural extramedullary ependymomas described, excluding ours. They were 21 females and 7 males; age was between 11 and 87 (average: 45.32; median: 46). The localization was in 15 cases thoracic, 3 cervical, 3 lumbar and 1 cervical–thoracic, in 6 cases were multifocal. Our case was very rare pathological entity, because it had various rare findings together, in fact ours ependymoma was: intradural, extramedullary, anaplastic and multifocal. Only 3 cases were described same as ours (Table 1). The etiopathogenesis was much discussed among the authors. Some, such as Duffau et al. in 2000, leaned towards a hormonal theory following the predominance of female sex in the patient population [5]. Other authors, the majority, did not accept the hormonal theory due to the presence of males among the patients and supported the theory of an origin from ependymal ectopic cells that remained trapped in the dural layers during the closure of the neural tube. This theory was supported by the fact that this type of tumor presented sometimes an attachment to the pial layer similar to an implant base from which tumor growth started [9, 10, 12]. The symptomatology of the lesion depended on its location and the degree of compression on the spinal cord or nerve roots.

Table 1 List of all intradural extramedullary ependymoma described in literature until our case

In all cases, MRI showed a well delineated intradural and extramedullary mass, hyperintense on T2-weighted images and hypo-hysointense on T1-weighted images and reinforced after gadolinium administration, except in the case of Graca et al. where the lesion was not reinforced after gadolinium administration, such that it looked like an arachnoid cyst [6, 14]. However, for their radiological characteristics, in most cases, as in our case, these malignant tumors were confused with spinal meningiomas or neurinomas, especially when they had an extradural component, as in the case of De Bonis et al. [4, 14].

Intraoperatively, these tumors were encapsulated with mild adhesions to the pial layer, except in 6 cases where adhesions were important. Indeed, Robles et al. and Guppy et al. described a vascular lesion with pial infiltration (similar to our case) [7]; Graves et al. and Iunes et al. described a tumor infiltrating the arachnoid membrane that required a fine dissection between the tumor and the spinal cord [8]; Li et al. and Krisman et al. on the other hand, described a tumor with tenacious adhesions with medulla that required a small amputation [10]. From the pathological point of view, we have found 7 cases of primary anaplastic Ependymoma, as in our case. The treatment considered by the various authors for the 28 cases found was very variable. All cases of benign ependymoma underwent complete surgical resection without additional treatment as recommended by et al.; while the 7 cases of primary malignant tumors, they were managed by the authors in various ways. Katoh et al. and Olive et al. after surgery, did not perform radiotherapy obtaining a favorable prognosis even though the follow-up period described was only a few months [9]. The group of Shurmans, Kinsman, Guppy and Chakravorty performed a complete resection and post-operative radiotherapy at the surgical site, as in our case [7, 10, 12]; Case et al., after complete resection of the anaplastic tumor, intended to perform radiotherapy but the patient refused the treatment, but after a year he had recurrence of the disease which was removed surgically followed radiotherapy to the whole central nervous system, with death after a month [3, 4, 12]. Regarding the formation of metastases in other levels of the spinal cord, we have found 2 cases. Some authors, such as Shurmans et al. hypothesized a migration of neoplastic cells from the primary tumor following the direction of the CSF circulation. In this way, they could explain why recurrences or metastases, in all cases reported in Table 1, occurred in a higher level of the spinal cord than in the primary intradural extramedullary ependymoma [8, 12, 13]. Regarding recurrences, they occurred in 7 cases: 5 cases were recurrences from grade II (WHO) ependymoma, while 2 were from grade III (WHO) ependymoma. All recurrences had anaplastic histology (grade III, WHO). Some authors have hypothesized that the recurrence was due to residual neoplastic cells that have undergone anaplastic transformation over time, without however explaining a precise mechanism. In our opinion, about this question, in literature there are very little information.

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