- Email: [email protected]
A rare case of dysembryoplastic neuroepithelial tumour in occipital lobe presenting with only headache
276 Hamada et al.
periphery, marginal doses also have been reduced.13 Some have used margin doses of 18–22 Gy in the 40–50% isodose (gamma knife) for volumes ranging from 11–25 cm3 .3 Others4 have kept the mean dose inside the nidus between 20 and 24 Gy with a margin dose of 18 Gy (at the 55–60% isodose centers). Statistically significant factors predictive of radiosurgical failure included higher Spetzler–Martin grade, increasing AVM volume, lower peripheral doses and a previous history of haemorrhage.14 The maximum diameter, angiographic shape of the AVM nidus and number of draining veins are also significant. Smaller, compact AVMs with fewer draining veins respond well. Radiation dose, angioarchitectural, haemodynamic aspects and flow pattern are also significant.15 Effective radiosurgical treatment for AVMs requires accurate definition of the true tri dimensional size and shape of the nidus. Over or underestimation may result in undue irradiation of normal brain tissue or sub optimal irradiation of the nidus leading to treatment failure.16 Failure to precisely define the target volume leads to poor response. This could be due to limitations of biplanar orthogonal X-ray angiography for 3D delineation of the AVM nidus4 though MR imaging as a supplemental imaging tool has been advocated.4 Stereotactic angiography alone, however, may not be the ideal database17 for radiosurgery because it can produce errors in the determination of the target center, size and shape, when compared with modern CT imaging.18 The shape of the lesion also determines the degree to which a ‘‘tight fit’’ can be obtained-that is the ability to place multiple collimators precisely over the nidus so as to generate a treatment plan which would ensure maximal radiation to the nidus and a steep fall out resulting in minimal radiation outside the nidus. The use of a number of isocenters is particularly crucial in formulating an ultra conformal treatment plan to cover the entire nidus. In large AVMs different arterial systems contribute to different portions of the nidus. Accurate delineation of each portion of the nidus is to be followed by ‘‘making’’ a composite nidus truly representative of the giant AVM. Failure in achieving angiographic obliteration is often due to imprecise definition of the target volume due to incomplete angiography.19 Imprecision is more when the target volume to be defined itself is large. Often the entire nidus may not be included in the prescription dose.5 For very large AVMs staged volume radiosurgery may result in considerable size reduction making it suitable for subsequent microsurgical resection.20
3. Gerhard P, Frank U, Georg P, Sandro E. Staged radiosurgical treatment for large benign cerebral lesions. J Neurosurg 2000; 93: 107–112. 4. Hung-chi P, Wan Y-G, Wen-Yuh C, Chenf-Ying S, Yue-Cune C, Ling-Wei W. Gamma Knife radiosurgery as a single treatment modality for large cerebral arterio venous malformations. J Neurosurg 2000; 93: 113–119. 5. Yamamoto M, Hara M, Ide E et al. Radiation related adverse effects observed on neuro-imaging several years after radiosurgery for cerebral arterio venous malformations. Surg Neurol 1998; 49: 385–398. 6. Kemeny AA, Dias PS, Forster DM. Results of Stereotactic radiosurgery of arterio venous malformations: an analysis of 52 cases. J Neurol Neurosurg Pshyciatry 1989; 52: 554–558. 7. Flickinger JC. An integrated logistic formula for prediction of complications form radiosurgery. Int J Radiat Oncol Biol Phys 1989; 17: 879–885. 8. Pollock BE, Flickinger JC, Kondziolka D et al. Indication and expectations of AVM radiosurgery. Contemp Neurosurg 1996; 18: 1–7. 9. Plasencia AR, De Salles AAF, Cabatan-Awang TDC et al. Combined embolization and Stereotactic radiosurgery for the treatment large-volume, high-risk arterio venous malformations. In: Kondziolka D (ed) Radiosurgery, vol. 13. Basel, Karge 2000; 161–167. 10. Dawson III RC, Tarr RW, Hecht ST et al. Treatment of Arteriovenous Malformations of the brain with combined embolisation and stereotactic radiosurgery: results after one and two years. AJNR 1990; 11: 857–864. 11. Barcia-Salorio JL, Barcia JA, Soler F, Hern andez G, Genov es JM. Stereotactic radiotherapy plus radiosurgical boost in the treatment of large cerebral arterio venous malformations. Acta Neurochir Suppl (Wien) 1993; 58: 98–100. 12. Yang K, Sang Ryong J, Jeong Hoon K, Jung Kyo L, Dong Sook R, Dong Joon L, Byung Duk K. Analysis of the causes of treatment failure in gamma knife radiosurgery for intracranial arterio venous malformations. J Neurosurg 2000; 93: 104–104. 13. Karlsson B, Lindquist C, Steiner L. Prediction of obliteration after gamma knife surgery for cerebral arterio venous malformations. Neurosurgery 1997; 40: 425–431. 14. Thomas LE, William AF, Frank JB, Paul SK. Analysis of treatment failure after radiosurgery for arteriovenous malformations. J Neurosurg 1998; 89: 104–110. 15. Jong Hee C, Jin Woo C, Yong Gou P, Sang Sup C. Factors related to complete occlusion of arterio venous malformation after gamma knife radiosurgery. J Neurosurg 2000; 93(Suppl 3): 96–101. 16. Spiegelmann R, Friedman WA, Bova FJ. Limitations of angiographic target localization in planning radiosurgical treatment. Neurosurgery 1992; 30: 619– 623. 17. Bova FJ, Friedman WA. Stereotactic angiography: an inadequate database for radiosurgery. Int J Radiat Oncol Biol Phys 1991; 20: 891–895. 18. David RB, William A, Friedman, Frank J. Bova: modifications based on computed tomographic imaging in planning the radiosurgical treatment of arteriovenous malformations. Neurosurgery 1993; 33: 588–596. 19. Ellis TL, Friedman WA, Bova FJ, Kublis PS, Buatti JM. Analysis of treatment failure after radiosurgery for arterio venous malformations. J Neurosurg 1998; 89: 104–110. 20. Firlik A, Levy E, Kondziolka D, Andrew D, Howard Y. Staged volume radiosurgery followed by microsurgical resection A novel treatment for giant cerebral AVM: a technical case report. Neurosurgery 1998; 43: 1223–1228.
CONCLUSION Large AVMs in non-eloquent areas, as over the corpus callosum, can be successfully obliterated, without complications, with stereotactic radiosurgery provided the angiographic nidus is accurately demarcated with pan angiography. Linear shape makes ultra conformal treatment planning more accurate. Size and volume alone should not be the criteria for choosing or rejecting stereotactic radiosurgery as a treatment option. The shape and location should also be considered.
A rare case of dysembryoplastic neuroepithelial tumour in occipital lobe presenting with only headache
ACKNOWLEDGEMENTS We are thankful to Mrs. Jayalakshmi and Mrs. Shobana Balaganapathy for secretarial assistance. REFERENCES 1. Pikus H, Beach ML, Harbaugh R. Microsurgical treatment of arterio venous malformations: analysis and comparison to stereotactic radiosurgery. J Neurosurg 1998; 88: 641–646. 2. Steiner L, Leksell L, Grietz T, Forster DM, Backlund EO. Stereotaxic radiosurgery for cerebral arterio venous malformations. Report of a case. Acta Chir Scand 1972; 138: 459–464.
Journal of Clinical Neuroscience (2003) 10(2)
Hideo Hamada MD, Masanori Kurimoto MD, Shoichi Nagai MD, Takashi Asahi MD, Yutaka Hirashima MD, Shunro Endo MD Department of Neurosurgery, Toyama Medical and Pharmaceutical University, Toyama, Japan
Summary We report an unusual case of dysembryoplastic neuroepithelial tumour (DNT) located in the occipital lobe presenting with only headache. A 31 year old woman presented with headache. She
ª 2003 Elsevier Science Ltd. All rights reserved.
Dysembryoplastic neuroepithelial tumour in occipital lobe
277
had no history of epilepsy and neurological examination revealed no abnormal findings. Computed tomography (CT) scanning revealed a multilobulated mass lesion with calcification in the right occipital lobe. Magnetic resonance (MR) imaging demonstrated a heterogeneously enhanced mass with hypointense signals on T1- and hyperintense signals on T2-weighted images. The lesion was totally resected and histopathologically diagnosed as DNT. Physicians must bear in mind that DNT may occur in the occipital lobe and present with only mass effect. c 2003 Elsevier Science Ltd. All rights reserved.
Journal of Clinical Neuroscience (2003) 10(2), 276–278 0967-5868/03/$ - see front matter ª 2003 Elsevier Science Ltd. All rights reserved. Doi:10.1016/S0967-5868(02)00267-9
Fig. 2 MR imaging demonstrating a heterogeneously enhanced mass lesion in the right occipital lobe, which was hypointense on T1- and hyperintense on T2-weighted images. (L: T1-WI, C: T2-WI, R: T1-Gd).
Keywords: dysembryoplastic neuroepithelial tumour, headache, occipital lobe Received 18 September 2001 Accepted 3 December 2001 Correspondence to: H. Hamada MD, Department of Neurosurgery, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan. Tel.: +76-434-2281; Fax: +76-434-5034.
INTRODUCTION DNT is a low-grade, mixed neuronal and glial tumour with little growth potential. It is usually associated with medically intractable seizures in young people and very rarely presents with mass effect. We report an unusual case of DNT in the right occipital lobe presenting with only headache.
CASE REPORT A 31 year old woman presented with a short history of headache at the parietal region with no exacerbation in the morning. She took a headache remedy, but it had no effect and the headache became worse and she consulted our hospital. General and neurological examination revealed no abnormal findings except blurred margin of the optic disc. She had no history of epilepsy. Computed tomography (CT) scanning revealed a multilobulated mass lesion with calcification in the right occipital lobe (Fig. 1). Magnetic resonance (MR) imaging demonstrated this lesion more clearly than that of CT. It was hypointense on T1- and hyperintense on T2-weighted images. This lesion was heterogeneously enhanced (Fig. 2). Angiography showed no abnormal findings and thallium single photon emission computed tomography (SPECT) revealed
Fig. 1 CT scanning revealing a multilobulated mass lesion with calcification in the right occipital lobe.
ª 2003 Elsevier Science Ltd. All rights reserved.
Fig. 3 Histopathological examination revealing a glioneuronal element, which was composed of predominant oligodendrocyte-like cells and prominent neurons floating within mucinous matrix (B) and main glial component composed of oligodendrocyte-like cells (A). (Hematoxylin-eosin. 200).
no abnormal perfusion. Preoperatively, we took these neuroradiological findings into account and suspected cavernous angioma or low-grade glioma as the differential diagnosis. At surgery, we performed gross total resection of the lesion using an occipital interhemispheric approach. The lesion was grayish-soft, easily aspirated, and moderately demarcated from the surrounding white matter. Histopathological examination revealed a glioneuronal element, composed of predominant oligodendrocyte-like cells and prominent neurons floating within mucinous matrix (Fig. 3A) and main glial component composed of oligodendrocyte-like cells (Fig. 3B). Mitosis and necrosis was not
Fig. 4 MR imaging 3 months after operation revealing no residual tumour. (L: T1-WI, R: T1-Gd).
Journal of Clinical Neuroscience (2003) 10(2)
278 Hamada et al.
observed. Immunohistochemically, oligodendrocyte-like cells were positive for S-100 protein, but negative for synaptophysin. Matrix was positive for glial fibrillary acidic protein and neurofilament. The histopathological diagnosis was DNT. Postoperatively, she developed a transient mild left homonymous hemianopia, but showed complete improvement. She was free from headache and the blurred margin of the optic disc had disappeared. MRI performed 3 months after operation showed no residual tumour (Fig. 4). DISCUSSION DNT is a new clinicopathological entity for benign brain tumour first proposed by Daumas-Duport et al. in 1988.1 DNT most commonly occurs in the supratentorial cortex, especially in the temporal lobe, followed by the frontal lobe.1–5 Only one case of DNT located in the occipital lobe was reported in the large series of 39 DNTs.1;6 Histopathologically, DNT is a benign multinodular lesion composed of glial and neuronal elements. DNTs share several important features with gangliogliomas and glioneuronal malformations, such as glioneuronal hamartomas and hamartias (small glioneuronal malformations).1;7;8 These consist of glial cells and highly differentiated ganglion cells.1;7 We must clearly differentiate DNTs from ganglioglioma and other low-grade gliomas. In the literature, only a few cases of DNT in the occipital lobe have been reported.1;3;6;9 Clinically, DNTs are usually associated with medically intractable partial seizures which date from childhood. DNTs may very rarely present with headache or increased intracranial pressure. Neuroradiological findings of DNT are usually characteristic. On CT scanning, DNT is usually moderately hypodense without edema. Some DNTs were enhanced with calcification and calvarial erosion.1;7;10 On MR imaging, DNT is a multicystic mass lesion which is hypointense on T1- and hyperintense on T2-weighted images with or without enhancement. Ostertun et al. reported that MR findings, interpreted with special attention to signs of multinodular and multicystic appearance, closely reflect the well-documented histopathologic growth pattern of DNT.11 In the present case, the patient presented with only a short history of headache. In addition, the location of the tumour was
Journal of Clinical Neuroscience (2003) 10(2)
unusual for DNT. Therefore, our preoperative differential diagnoses did not include DNT, although the neuroradiological findings in the present case were consistent with those of DNT. DNT should be differentiated from other tumours in the occipital lobe, even in patients without epilepsy.
REFERENCES 1. Daumas-Duport C, Scheithauer BW, Chodkiewicz JP, Laws Jr ER, Vedrenne C. Dysembryoplastic neuroepithelial tumour: a surgically curable tumor of young patients with intractable partial seizures. Neurosurgery 1988; 23: 545–556. 2. Abe M, Tabuchi K, Takehisa T, Shiraishi T, Koga H, Takagi M. Dysembryoplastic neuroepithelial tumor: report of three cases. Surg Neurol 1995; 43: 240–245. 3. Asano E, Suzuki E, Shamoto H, Otsuki T, Yoshimoto T. Pathological features of dysembryoplastic neuroepithelial tumor: study of five surgical cases with intractable epilepsies. No Shinkei Geka (Japan) 1999; 27: 541–547. 4. Raymond AA, Halpin SF, Alsanjari N, Cook MJ, Kitchen ND, Fish DR, Stevens JM, Harding BN, Scaravilli F, Kendall B, Shorvon SD, Neville BGR. Dysembryoplastic neuroepithelial tumor: features in 16 patients. Brain 1994; 117: 461–475. 5. Thom M, Gomez-Anson B, Revesz T, Harkness W, OÕBrien CJ, Kett-White R, Jones EW, Stevens J, Scaravilli F. Spontaneous intralesional haemorrhage in dysembryopalstic neuroepithelial tumors: a series of five cases. J Neurol Neurosurg Psychiatry 1999; 67: 97–101. 6. Daumas-Duport C, Varlet P, Bacha S, Beuvon F, Cervera-Pierot P, Chodkiewicz JP. Dysembryoplastic neuroepithelial tumors: nonspecific histlogical forms – a study of 40 cases. J Neurooncol 1999; 41: 267–280. 7. Hirose T, Schithouer BW, Lopes MBS, Vandenberg SR. Dysembryoplastic neuroepithelial tumor (DNT): a immunohistochemical and ultrastructural study. J Neuropathol Exp Neurol 1994; 53: 184–195. 8. Wolf HK, Wellmer J, Muler MB, Wiestler OD, Hufnagel A, Pietsch T. Glioneural malformative lesions and dysembryoplastic neuroepithelial tumors in patient with chronic pharmacoresistant epilepsies. J Neuropathol Exp Neurol 1995; 54: 245–254. 9. Taratuto AL, Pomato G, Sevlever, Gallo G, Monges J. Dysembryoplastic neuroepithelial tumor: morphological, immunocytochemical, and deoxyribonucleic acid analyses in a pediatric series. Neurosurgery 1995; 36: 474–481. 10. Gottschalk J, Koeves M, Skotzek-Konrad B, Goebel S, Cervos-Navarro J. Dysembryoplastic neuroepithelial tumor in a 75-year-old patient with long-standing epilepsy. Clin Neuropathol 1993; 12: 175–178. 11. Ostertun B, Wolf HK, Campos MG, Matus C, Solymosi L, Elger CE, Schramm J, Schild HH. Dysembryoplastic neuroepithelial tumors: MR and CT evaluation. AJNR 1996; 17: 419–430.
ª 2003 Elsevier Science Ltd. All rights reserved.
periphery, marginal doses also have been reduced.13 Some have used margin doses of 18–22 Gy in the 40–50% isodose (gamma knife) for volumes ranging from 11–25 cm3 .3 Others4 have kept the mean dose inside the nidus between 20 and 24 Gy with a margin dose of 18 Gy (at the 55–60% isodose centers). Statistically significant factors predictive of radiosurgical failure included higher Spetzler–Martin grade, increasing AVM volume, lower peripheral doses and a previous history of haemorrhage.14 The maximum diameter, angiographic shape of the AVM nidus and number of draining veins are also significant. Smaller, compact AVMs with fewer draining veins respond well. Radiation dose, angioarchitectural, haemodynamic aspects and flow pattern are also significant.15 Effective radiosurgical treatment for AVMs requires accurate definition of the true tri dimensional size and shape of the nidus. Over or underestimation may result in undue irradiation of normal brain tissue or sub optimal irradiation of the nidus leading to treatment failure.16 Failure to precisely define the target volume leads to poor response. This could be due to limitations of biplanar orthogonal X-ray angiography for 3D delineation of the AVM nidus4 though MR imaging as a supplemental imaging tool has been advocated.4 Stereotactic angiography alone, however, may not be the ideal database17 for radiosurgery because it can produce errors in the determination of the target center, size and shape, when compared with modern CT imaging.18 The shape of the lesion also determines the degree to which a ‘‘tight fit’’ can be obtained-that is the ability to place multiple collimators precisely over the nidus so as to generate a treatment plan which would ensure maximal radiation to the nidus and a steep fall out resulting in minimal radiation outside the nidus. The use of a number of isocenters is particularly crucial in formulating an ultra conformal treatment plan to cover the entire nidus. In large AVMs different arterial systems contribute to different portions of the nidus. Accurate delineation of each portion of the nidus is to be followed by ‘‘making’’ a composite nidus truly representative of the giant AVM. Failure in achieving angiographic obliteration is often due to imprecise definition of the target volume due to incomplete angiography.19 Imprecision is more when the target volume to be defined itself is large. Often the entire nidus may not be included in the prescription dose.5 For very large AVMs staged volume radiosurgery may result in considerable size reduction making it suitable for subsequent microsurgical resection.20
3. Gerhard P, Frank U, Georg P, Sandro E. Staged radiosurgical treatment for large benign cerebral lesions. J Neurosurg 2000; 93: 107–112. 4. Hung-chi P, Wan Y-G, Wen-Yuh C, Chenf-Ying S, Yue-Cune C, Ling-Wei W. Gamma Knife radiosurgery as a single treatment modality for large cerebral arterio venous malformations. J Neurosurg 2000; 93: 113–119. 5. Yamamoto M, Hara M, Ide E et al. Radiation related adverse effects observed on neuro-imaging several years after radiosurgery for cerebral arterio venous malformations. Surg Neurol 1998; 49: 385–398. 6. Kemeny AA, Dias PS, Forster DM. Results of Stereotactic radiosurgery of arterio venous malformations: an analysis of 52 cases. J Neurol Neurosurg Pshyciatry 1989; 52: 554–558. 7. Flickinger JC. An integrated logistic formula for prediction of complications form radiosurgery. Int J Radiat Oncol Biol Phys 1989; 17: 879–885. 8. Pollock BE, Flickinger JC, Kondziolka D et al. Indication and expectations of AVM radiosurgery. Contemp Neurosurg 1996; 18: 1–7. 9. Plasencia AR, De Salles AAF, Cabatan-Awang TDC et al. Combined embolization and Stereotactic radiosurgery for the treatment large-volume, high-risk arterio venous malformations. In: Kondziolka D (ed) Radiosurgery, vol. 13. Basel, Karge 2000; 161–167. 10. Dawson III RC, Tarr RW, Hecht ST et al. Treatment of Arteriovenous Malformations of the brain with combined embolisation and stereotactic radiosurgery: results after one and two years. AJNR 1990; 11: 857–864. 11. Barcia-Salorio JL, Barcia JA, Soler F, Hern andez G, Genov es JM. Stereotactic radiotherapy plus radiosurgical boost in the treatment of large cerebral arterio venous malformations. Acta Neurochir Suppl (Wien) 1993; 58: 98–100. 12. Yang K, Sang Ryong J, Jeong Hoon K, Jung Kyo L, Dong Sook R, Dong Joon L, Byung Duk K. Analysis of the causes of treatment failure in gamma knife radiosurgery for intracranial arterio venous malformations. J Neurosurg 2000; 93: 104–104. 13. Karlsson B, Lindquist C, Steiner L. Prediction of obliteration after gamma knife surgery for cerebral arterio venous malformations. Neurosurgery 1997; 40: 425–431. 14. Thomas LE, William AF, Frank JB, Paul SK. Analysis of treatment failure after radiosurgery for arteriovenous malformations. J Neurosurg 1998; 89: 104–110. 15. Jong Hee C, Jin Woo C, Yong Gou P, Sang Sup C. Factors related to complete occlusion of arterio venous malformation after gamma knife radiosurgery. J Neurosurg 2000; 93(Suppl 3): 96–101. 16. Spiegelmann R, Friedman WA, Bova FJ. Limitations of angiographic target localization in planning radiosurgical treatment. Neurosurgery 1992; 30: 619– 623. 17. Bova FJ, Friedman WA. Stereotactic angiography: an inadequate database for radiosurgery. Int J Radiat Oncol Biol Phys 1991; 20: 891–895. 18. David RB, William A, Friedman, Frank J. Bova: modifications based on computed tomographic imaging in planning the radiosurgical treatment of arteriovenous malformations. Neurosurgery 1993; 33: 588–596. 19. Ellis TL, Friedman WA, Bova FJ, Kublis PS, Buatti JM. Analysis of treatment failure after radiosurgery for arterio venous malformations. J Neurosurg 1998; 89: 104–110. 20. Firlik A, Levy E, Kondziolka D, Andrew D, Howard Y. Staged volume radiosurgery followed by microsurgical resection A novel treatment for giant cerebral AVM: a technical case report. Neurosurgery 1998; 43: 1223–1228.
CONCLUSION Large AVMs in non-eloquent areas, as over the corpus callosum, can be successfully obliterated, without complications, with stereotactic radiosurgery provided the angiographic nidus is accurately demarcated with pan angiography. Linear shape makes ultra conformal treatment planning more accurate. Size and volume alone should not be the criteria for choosing or rejecting stereotactic radiosurgery as a treatment option. The shape and location should also be considered.
A rare case of dysembryoplastic neuroepithelial tumour in occipital lobe presenting with only headache
ACKNOWLEDGEMENTS We are thankful to Mrs. Jayalakshmi and Mrs. Shobana Balaganapathy for secretarial assistance. REFERENCES 1. Pikus H, Beach ML, Harbaugh R. Microsurgical treatment of arterio venous malformations: analysis and comparison to stereotactic radiosurgery. J Neurosurg 1998; 88: 641–646. 2. Steiner L, Leksell L, Grietz T, Forster DM, Backlund EO. Stereotaxic radiosurgery for cerebral arterio venous malformations. Report of a case. Acta Chir Scand 1972; 138: 459–464.
Journal of Clinical Neuroscience (2003) 10(2)
Hideo Hamada MD, Masanori Kurimoto MD, Shoichi Nagai MD, Takashi Asahi MD, Yutaka Hirashima MD, Shunro Endo MD Department of Neurosurgery, Toyama Medical and Pharmaceutical University, Toyama, Japan
Summary We report an unusual case of dysembryoplastic neuroepithelial tumour (DNT) located in the occipital lobe presenting with only headache. A 31 year old woman presented with headache. She
ª 2003 Elsevier Science Ltd. All rights reserved.
Dysembryoplastic neuroepithelial tumour in occipital lobe
277
had no history of epilepsy and neurological examination revealed no abnormal findings. Computed tomography (CT) scanning revealed a multilobulated mass lesion with calcification in the right occipital lobe. Magnetic resonance (MR) imaging demonstrated a heterogeneously enhanced mass with hypointense signals on T1- and hyperintense signals on T2-weighted images. The lesion was totally resected and histopathologically diagnosed as DNT. Physicians must bear in mind that DNT may occur in the occipital lobe and present with only mass effect. c 2003 Elsevier Science Ltd. All rights reserved.
Journal of Clinical Neuroscience (2003) 10(2), 276–278 0967-5868/03/$ - see front matter ª 2003 Elsevier Science Ltd. All rights reserved. Doi:10.1016/S0967-5868(02)00267-9
Fig. 2 MR imaging demonstrating a heterogeneously enhanced mass lesion in the right occipital lobe, which was hypointense on T1- and hyperintense on T2-weighted images. (L: T1-WI, C: T2-WI, R: T1-Gd).
Keywords: dysembryoplastic neuroepithelial tumour, headache, occipital lobe Received 18 September 2001 Accepted 3 December 2001 Correspondence to: H. Hamada MD, Department of Neurosurgery, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan. Tel.: +76-434-2281; Fax: +76-434-5034.
INTRODUCTION DNT is a low-grade, mixed neuronal and glial tumour with little growth potential. It is usually associated with medically intractable seizures in young people and very rarely presents with mass effect. We report an unusual case of DNT in the right occipital lobe presenting with only headache.
CASE REPORT A 31 year old woman presented with a short history of headache at the parietal region with no exacerbation in the morning. She took a headache remedy, but it had no effect and the headache became worse and she consulted our hospital. General and neurological examination revealed no abnormal findings except blurred margin of the optic disc. She had no history of epilepsy. Computed tomography (CT) scanning revealed a multilobulated mass lesion with calcification in the right occipital lobe (Fig. 1). Magnetic resonance (MR) imaging demonstrated this lesion more clearly than that of CT. It was hypointense on T1- and hyperintense on T2-weighted images. This lesion was heterogeneously enhanced (Fig. 2). Angiography showed no abnormal findings and thallium single photon emission computed tomography (SPECT) revealed
Fig. 1 CT scanning revealing a multilobulated mass lesion with calcification in the right occipital lobe.
ª 2003 Elsevier Science Ltd. All rights reserved.
Fig. 3 Histopathological examination revealing a glioneuronal element, which was composed of predominant oligodendrocyte-like cells and prominent neurons floating within mucinous matrix (B) and main glial component composed of oligodendrocyte-like cells (A). (Hematoxylin-eosin. 200).
no abnormal perfusion. Preoperatively, we took these neuroradiological findings into account and suspected cavernous angioma or low-grade glioma as the differential diagnosis. At surgery, we performed gross total resection of the lesion using an occipital interhemispheric approach. The lesion was grayish-soft, easily aspirated, and moderately demarcated from the surrounding white matter. Histopathological examination revealed a glioneuronal element, composed of predominant oligodendrocyte-like cells and prominent neurons floating within mucinous matrix (Fig. 3A) and main glial component composed of oligodendrocyte-like cells (Fig. 3B). Mitosis and necrosis was not
Fig. 4 MR imaging 3 months after operation revealing no residual tumour. (L: T1-WI, R: T1-Gd).
Journal of Clinical Neuroscience (2003) 10(2)
278 Hamada et al.
observed. Immunohistochemically, oligodendrocyte-like cells were positive for S-100 protein, but negative for synaptophysin. Matrix was positive for glial fibrillary acidic protein and neurofilament. The histopathological diagnosis was DNT. Postoperatively, she developed a transient mild left homonymous hemianopia, but showed complete improvement. She was free from headache and the blurred margin of the optic disc had disappeared. MRI performed 3 months after operation showed no residual tumour (Fig. 4). DISCUSSION DNT is a new clinicopathological entity for benign brain tumour first proposed by Daumas-Duport et al. in 1988.1 DNT most commonly occurs in the supratentorial cortex, especially in the temporal lobe, followed by the frontal lobe.1–5 Only one case of DNT located in the occipital lobe was reported in the large series of 39 DNTs.1;6 Histopathologically, DNT is a benign multinodular lesion composed of glial and neuronal elements. DNTs share several important features with gangliogliomas and glioneuronal malformations, such as glioneuronal hamartomas and hamartias (small glioneuronal malformations).1;7;8 These consist of glial cells and highly differentiated ganglion cells.1;7 We must clearly differentiate DNTs from ganglioglioma and other low-grade gliomas. In the literature, only a few cases of DNT in the occipital lobe have been reported.1;3;6;9 Clinically, DNTs are usually associated with medically intractable partial seizures which date from childhood. DNTs may very rarely present with headache or increased intracranial pressure. Neuroradiological findings of DNT are usually characteristic. On CT scanning, DNT is usually moderately hypodense without edema. Some DNTs were enhanced with calcification and calvarial erosion.1;7;10 On MR imaging, DNT is a multicystic mass lesion which is hypointense on T1- and hyperintense on T2-weighted images with or without enhancement. Ostertun et al. reported that MR findings, interpreted with special attention to signs of multinodular and multicystic appearance, closely reflect the well-documented histopathologic growth pattern of DNT.11 In the present case, the patient presented with only a short history of headache. In addition, the location of the tumour was
Journal of Clinical Neuroscience (2003) 10(2)
unusual for DNT. Therefore, our preoperative differential diagnoses did not include DNT, although the neuroradiological findings in the present case were consistent with those of DNT. DNT should be differentiated from other tumours in the occipital lobe, even in patients without epilepsy.
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