International Journal of Neurooncology

: 2019  |  Volume : 2  |  Issue : 1  |  Page : 7--11

Simultaneously occurring tumors with acoustic schwannomas without phakomatoses – A case series of nine patients and review of literature

Dattatraya P Muzumdar1, Sonal Jain2, Abhidha Shah1, Atul Goel1,  
1 Department of Neurosurgery, KEM Hospital, Mumbai, Maharashtra, India
2 Department of Neurosurgery, B.Y.L. Nair Charitable Hospital, Mumbai, Maharashtra, India

Correspondence Address:
Dr. Sonal Jain
802, Boy's Wing, UGPG Hostel, KEMH Campus, Parel, Mumbai - 400 012, Maharashtra


Introduction: Primary brain tumors of different histological types developing spontaneously together is a rare event; the incidence being 0.3% of all brain tumors. Acoustic schwannomas form the majority (about 70%–80%) of all cerebellopontine angle tumors. The most common association found is meningioma and acoustic schwannoma occurring in the same cerebellopontine angle region. Excluding phakomatoses, other neurocutaneous syndromes, and previous irradiation; the simultaneous occurrence of different primary brain tumors with acoustic schwannoma is rare. Methodology: We report the largest single institute case series, 9 patients of simultaneously occurring primary tumors with acoustic schwannomas over the last 25 years (1990–2015). All these patients were operated for both the tumors. The classification, pathogenesis, and surgical strategy of such tumors are discussed in light of current literature. Results: There were five males and four females in the study population aged from 30-60 years. There were five patients with spatially distant co-existing tumors. Transient facial paresis was noticed in three patients. They had significant improvement within six months. Conclusion: Simultaneously occurring tumors need appropriate planning and surgical strategy for ensuring good outcome and long-term prognosis.

How to cite this article:
Muzumdar DP, Jain S, Shah A, Goel A. Simultaneously occurring tumors with acoustic schwannomas without phakomatoses – A case series of nine patients and review of literature.Int J Neurooncol 2019;2:7-11

How to cite this URL:
Muzumdar DP, Jain S, Shah A, Goel A. Simultaneously occurring tumors with acoustic schwannomas without phakomatoses – A case series of nine patients and review of literature. Int J Neurooncol [serial online] 2019 [cited 2020 Feb 26 ];2:7-11
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Simultaneous development of primary brain tumors of different histological types is infrequent. The incidence is 0.3% of all brain tumors. They are relatively common in phakomatoses, neurocutaneous syndromes, and previous irradiation. Sporadic acoustic schwannomas coexisting with histologically distinct tumors are rare. There are various theories, which attempt at explaining this association. The operative strategy has to be customized as per the tumors, their location and behavior to evade postoperative deficits, and in particular, cranial nerve dysfunctions. We present the largest single institute series of coexisting tumors with acoustic schwannomas in nine patients excluding those with previous irradiation or presence of neurocutaneous syndromes such as neurofibromatosis. The clinical and intraoperative significance of such an association is described and discussed in light of the relevant literature on the subject.


A retrospective review of nine patients with simultaneously occurring tumors with acoustic schwannomas treated in a tertiary care center in India over the last 20 years (1990–2015) is presented. They do not have any association with phakomatoses. The clinical features, imaging characteristics, surgical strategy, and outcome were retrieved from the available records and analyzed.


There were nine patients identified over the last 20 years from 1985 to 2015 in our institute who harbored simultaneous histologically distinct primary brain tumors. The demographic and tumor profile of the patients has been summarized in [Table 1].{Table 1}

All the patients belong to the age group of 30–60 years. There were five males and four females. There is no site predilection noted as acoustic tumors in the left as well as right cerebellopontine angles have coexisting tumors. There were five cases of spatially distant coexisting tumors [Figure 1]a, [Figure 1]b and [Figure 2]a, [Figure 2]b, [Figure 2]c. The tumors in a similar location were operated at the same time. The symptomatic tumor was operated first. All patients were operated successfully for both the tumors eventually [Figure 3] and [Figure 4]a, [Figure 4]b. Transient postoperative facial paresis was present in three patients. They had significant improvement at follow-up after 6 months.{Figure 1}{Figure 2}{Figure 3}{Figure 4}


The incidence of simultaneously occurring histologically distinct primary brain tumors is about 0.3% of all brain tumors. This coexistence is a well-known fact in patients with neurocutaneous syndromes or history of previous radiation exposure. Cushing and Eisenhardt published the simultaneous existence of a meningioma and glioma in their treatise on meningiomas.[1] The most frequent coexisting tumor with acoustic schwannomas is a meningioma. The radiologists reported these tumors as a single entity permitting the revelation to be an intraoperative surprise. We report the largest single institute series of 9 patients.

Acoustic schwannoma, the most frequent tumor of the cerebellopontine angle, is known to coexist with various tumors such as meningioma and glioma in neurofibromatosis patients. Sporadic association is seldom encountered in nonphakomatosis patients. There are only about 23 isolated citations [Table 2] of tumors simultaneously occurring with acoustic schwannoma in patients excluding radiation and neurocutaneous syndromes.{Table 2}

The second tumor is often situated in the same cerebellopontine angle as the acoustic in almost 48% of such patients. Spatially distinct and far away simultaneous tumors are infrequent. Gardner and Turner in 1939 identified meningiomas coexisting with acoustic schwannomas in the same site.[10] They envisaged central neurofibromatosis, a pathological state involving the connective tissue of the nervous system, wherein gliomas, meningiomas, and schwannomas are all parts of one larger picture. This coexistence was rather thought as an abortive or incomplete form of von Recklinghausen's disease. While there is genetic evidence pointing toward chromosome 22 as the pathological trigger in some of the cases of simultaneous tumors, definite unequivocal causal relationship is not confirmed.

Glioma and epidermoid cyst follow meningioma in order of association. Patients with epidermoid cyst in the contralateral cerebellopontine angle as well as interhemispheric fissures have been reported. Doherty et al. have worked on paracrine stimulation of epithelial rests by a primary tumor leading to the formation of an epidermoid cyst.[25] Other theories mention the role of irritants and oncogenic factors released in Cerebrospinal fluid (CSF) by the acoustic tumor leading to the formation of epidermoid cysts.

The tumors can act as irritants or sources of local growth factors to induce the formation of a de novo tumor nearby. The origin in meningioma is thought to be secondary to irritation of the arachnoid cap cells in this manner. However, meningioma is known to produce local growth factors and cytokines sufficient to induce glioma formation.

The embryonic cell rest theory by Connheim believes in the presence of embryonic rests in certain locations, which make them vulnerable to the occurrence of simultaneous tumors. The left cerebellopontine angle was thought to have such embryonic rests. Albeit being the most common side to have simultaneous tumors, there is not much evidence to suggest that potential embryonic rests in the left cerebellopontine angle are the culprit for simultaneous tumors. Four patients (50%) had right-sided cerebellopontine angle simultaneous tumors in our series. The physical irritation of the dura mater, local paracrine stimulation, and epidermal and fibroblast growth factor ligand action are possible etiological factors.[26]

It is interesting to believe the existence of a common progenitor cell with bidirectional differentiation giving rise to such tumors. However, no such cell has been identified so far.

Recent advances have witnessed the development of “field cancerisation” theory. Within this theory, it is upheld that a tumor often induces formation of a localized “field” of cancer prone tissue in its vicinity.[27] This theory gains encouragement from field changes in the respiratory epithelium and precancerous changes in mucosal tissues around the malignant region. The validity of these premalignant states in the central nervous system at present is doubtful.

A multitude of diverse potential theories thus have been proposed to rationalize the coexistence of these tumors. The exact conclusive evidence still eludes us. There is always a chance that this coexistence is random coincidence.

Frassanito et al.[14] developed the taxonomical organization of these tumors based on their histological and radiological properties [Table 3].{Table 3}

It is important to know the association preoperatively as they do have implications on the operative management. Acoustic schwannomas revere the arachnoid membrane, but coexisting meningiomas not infrequently cause undue adherence to the same leading to operative difficulty. This might explain the propensity for enhanced neurological deficits seen in these patients.

The era of magnetic resonance imaging has witnessed an upsurge in the preoperative diagnosis of these tumors. The clinical profile includes a range of symptoms not explained by a single tumor. Intraoperative distinct cerebral edema is a vital sign.

The tumors located in the same anatomic compartment in five patients were operated in the same sitting. In case of spatially distant tumors, the more symptomatic tumor was tackled first followed by excision of the second tumor in a different setting. While the acoustic schwannoma was preferentially operated in the patient with a simultaneously occurring interhemispheric epidermoid cyst, the insular glioma was tackled before the acoustic schwannoma in another patient [Figure 3] and [Figure 4]a, [Figure 4]b. There are no set rules regarding which tumor to operate first or remove them simultaneously. The operative strategy was individualized as the presence of another tumor added to the difficulty in maintaining the arachnoid plane and preserving the cranial nerves. The postoperative facial paresis rate is similar to isolated acoustic tumor in our series.


The sporadic occurrence of simultaneous tumors is not common. There should be a heightened awareness of this entity among clinicians and radiologists. The operative strategy in such tumors should be planned meticulously to achieve maximal resection and minimal neurological deficits. A diligent approach can lead to a gratifying outcome.

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Conflicts of interest

There are no conflicts of interest.


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