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| Year : 2001 | Volume
: 49
| Issue : 3 | Page : 291-4 |
Disappearing cystic cerebellar medulloblastoma : the ghost tumour.
Gupta V, Kumar S, Tatke M, Singh A, Sinha S, Singh D
Department of Neurosurgery, Gobind Ballabh Pant Hospital, Jawahar Lal Nehru Marg, New Delhi-110 002, India.
Correspondence Address:
Department of Neurosurgery, Gobind Ballabh Pant Hospital, Jawahar Lal Nehru Marg, New Delhi-110 002, India.
[email protected]
A case of medulloblastoma, which disappeared following steroid administration and a single sitting of radiotherapy (8Gy) is presented. At surgical exploration tumour was not found, multiple biopsies were negative. Post operative CT scan too did not show the tumour. Five months later, tumour reappeared in left cerebellar lobe in cystic and solid form. Patient was reoperated and tumour was decompressed. The biopsy showed medulloblastoma. To our knowledge, medulloblastomas are not known to be completely responsive to either of these modalities.
How to cite this article:
Gupta V, Kumar S, Tatke M, Singh A, Sinha S, Singh D. Disappearing cystic cerebellar medulloblastoma : the ghost tumour. Neurol India 2001;49:291 |
Medulloblastomas constitute about 4% of all the brain tumours and represent 15-25% of the primary central nervous system (CNS) tumours in children, however, only less than 1% of these occur in adults.[1],[2],[3],[4] We came across an interesting case of medulloblastoma, which disappeared after one sitting of radiotherapy (8Gy) and steroid administration at a peripheral center. No tumour was found on surgical exploration and multiple biopsies were negative. It reappeared after five months and was subsequently excised from radiological presumed tumour area. No such clinical course of a medulloblastoma has been reported previously.
A 17 years old girl presented to neurosurgery out patient department with history of progressively worsening headache and vomiting of six months duration. She had difficulty in maintaining her balance since one month and blurring of vision and diplopia for the last two weeks. She was referred from a peripheral hospital where computed tomography scan had [Figure. 1] shown an ill-defined midline posterior fossa mass, enhancing on contrast with effacement of fourth ventricle and associated hydrocephalous. She had received treatment in the form of dexamethasone (4 mg) three times a day for two weeks, phenytoin sodium (100mg) three times a day for two weeks and radiotherapy (one sitting 8 Gy) one week prior to admission.
On examination, she was a young girl of average built and was conscious and well oriented. Visual acuity was normal; however she had bilateral papilloedema. Eye movements were restricted due to bilateral sixth nerve palsy. She had bilateral cerebellar signs. No other neurological deficit was elicited. Steroid therapy was discontinued on admission to this hospital. A right ventriculo peritoneal shunt was put in to decompress the obstructed ventricles. CSF pressure was markedly raised. Malignant cells were negative. One week later, she was operated on by midline suboccipital craniectomy. Vermis was split however no abnormal tumour tissue was seen. Multiple biopsies were taken, which revealed normal cerebellar cortex and white matter. No tumour or inflammatory lesion was seen. No organism could be identified on special staining. Postoperative computerized tomography [Figure. 2] revealed no evidence of tumour. She was discharged on [eighth] postoperative day. Ultrasonography of the abdomen revealed no abnormality. She was relieved of her presenting symptoms i.e. headache and vomiting and there was improvement in ataxia. Followup examination after five months revealed significant left sided cerebellar signs. CT Scan [Figure. 3] revealed a mass in left cerebellar hemisphere with large cystic component and small solid component. MRI [Figure. 4] revealed a left cerebellar mass, which was hypointense on T1WI and hyperintense on T2WI. On gadolinium administration, the solid component located medially showed heterogeneous enhancement. She was operated by left sub occipital craniectomy. Cystic and solid mass was found about 1 cm below the cortical surface. Cyst fluid contained xanthochromic fluid. Solid component was reddish gray, soft friable, moderately vascular, was infiltrative and had no clear margins from the surrounding brain. Histopathological examination revealed medulloblastoma. She was then subjected to cranio spinal irradiation. She is on regular follow up with no fresh symptoms.
Ghost tumour or disappearing tumours have been described in relation to an intraventricular primary malignant lymphoma with negative exploration.[5] Computerized tomography scan showed complete disappearance on steroids. It reappeared two months later and diagnosis was confirmed on post mortem examination. Coca et al[6] reported a lady with bilateral frontal masses which enhanced on contrast administration. She was receiving dexamethasone on a presumptive diagnosis of metastasis. Repeat scan three weeks later revealed no tumour. The steroids were discontinued and patient deteriorated. Computerized tomography scans showed bilateral frontal masses. Stereotactic biopsy was negative. Diagnosis of cerebral lymphoma was confirmed on autopsy a few days later. Buxton et al[7] reported a case of left fronto parietal glioblastoma multiforme, which disappeared for about three weeks following steroid administration by the referring hospital. It reappeared at the same site three weeks later when the steroids were withdrawn. In this case, we believe that the first lesion was a medulloblastoma, which regressed by therapeutic measure like steroids and radiotherapy and resurfaced after five months.
Since their introduction more than thirty years ago, glucocorticoids have been used extensively as the main stay therapy for tumour associated oedema. The rationale for steroid use in tumour associated oedema is largely empirical, for the mechanism by which steroids mediate their anti oedema effects remains very much an enigma.[8] It is generally accepted that the beneficial effects of steroids are primarily related to reduction in permeability of disrupted blood brain barrier.[9],[10] Various mechanisms postulated include inhibition of phospholipase A2 (the enzyme responsible for arachidonic acid release), stabilisation of membrane lysosomes (a direct stabilizing effect on cerebral capillaries), and an improvement in peritumoural micro circulation.[8],[9],[10] Anderson et al[11] demonstrated 50% reduction in peritumoural oedema after one-week of steroids. Sherbet et al[12] demonstrated inhibition of incorporation of radio actively labeled thymidine into the deoxyribonucleic acid (DNA) of the cells and by the increase in generation time of cells exposed to the drug in vitro. Many other studies have reported similar inhibitory effects of steroids.[13],[14],[15] Sandhu and Kendall[16] in a retrospective study of 116 patients of medulloblastoma described cystic changes or non enhancing areas in 47%, where as Bourgouin et al[17] reported cystic areas in 82% of adult patients. Zee et al[18] described cyst formation in 17% of paediatric patients with medulloblastoma. Mahapatra et al[19] reported a case of a cystic medulloblastoma without any solid component. In the present case, the tumour was solid initially, but subsequently had cystic component.
Rare cases of multifocal cerebellar medulloblastomas have been described in the literature.[20],[21] In one of the reports there was simultaneous appearance of lesions in both the cerebellar lobes, in the other report, lesions were detected simultaneously in both cerebellar lobes and occipital lobe in adult patients. However, both the authors were unable to determine exactly whether the multiple cerebellar foci developed simultaneously or as a result of CSF seedling. In our case, the multifocal origin does not explain the regression of original lesion. We could not find any report of disappearance of medulloblastoma either spontaneously or by radio therapy.
Medulloblastoma in adults is considered different from children in respect to location. It is more common in paramedian and lateral locations in adults as was true in our case, in contrast to midline location in children. Histologically, desmoplastic variant is common in adults. Some authors have observed that somehow medulloblastoma loses its aggressive malignant behavior with advancing age.[22]
This clinical dilemma supports the need for histopathological confirmation before embarking on a course of therapy. On rare occasions when no tumour is found on surgical exploration, possibility of disappearing tumours should be kept in mind. If patient is receiving steroids, the same may be withdrawn and radiological study should be repeated.
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