Indian Journal of Cancer Medknow Publications on behalf of Indian Cancer Society ISSN: 0019-509X EISSN: 1998-4774 Vol. 48, Num. 2, 2011, pp. 256-258

Indian Journal of Cancer, Vol. 48, No. 2, April-June, 2011, pp. 256-258

Letter to Editor

Delayed intracerebral radiation necrosis occurring a decade after conventional radiotherapy in a patient of diffuse astrocytoma

AD Banerjee, P Pandey, ID Bhagavatulla

Department of Neurosurgery, National Institute of Mental Health and Neuro Sciences, Bangalore 560029, India

Correspondence Address: P Pandey Department of Neurosurgery, National Institute of Mental Health and Neuro Sciences, Bangalore 560029 India paritosh2000@gmail.com

Code Number: cn11062

DOI: 10.4103/0019-509X.82881

Sir,

A 46-year-old man presented with features of raised intracranial pressure of 10 months duration and left-sided focal motor seizures due to the presence of right posterior frontal tumor in March 1996. The tumor was excised via a right fronto-parietal approach. Histological examination showed evidence of protoplasmic astrocytoma (WHO grade II). Following the operation, he received a total dose of 60 Gy conventional external beam radiotherapy in 28 fractions. Subsequent routine clinico-radiological follow-ups were within normal limits.

In November 2006, patient presented with history of relapse of seizures of similar semiology, for the past 2 years. Computed tomography and MR-imagings (with MR spectroscopy) [Figure - 1] were suggestive of recurrence of the tumor: a mixed density relatively well-defined lesion with high choline peaks, diminished NAA peaks, and increased choline/creatinine ratio.

He was admitted to our hospital and was operated for the tumor with reexploration of the same craniotomy flap. On admission, the patient showed no neurological deficits. The mass was located on the surface with widened superior and middle frontal gyri; tumor was mainly cystic multiloculated, filled with xanthochromic fluid. The walls of the cyst-stained yellow due to old blood, the solid component was scanty, stringy, avascular, and diffuse, with no plane of cleavage. The mass was removed gross-total. Histopathological examination revealed necrotic tissue consisting of fibrinoid and hyaline material, and inflammatory response with invasion of neutrophils and vascular endothelial proliferation, but no evidence of neoplastic cells [Figure - 2]. CT imaging 1 day after surgery showed significant reduction in mass-effect with residual edema [Figure - 3]. After surgery, the patient′s seizures got controlled on oral phenytoin in appropriate dosage. After 2 years of follow-up, the patient is doing well, with no deficits or new lesion [Figure - 4].

Radiation necrosis, even delayed, is probably not an uncommon finding, as noted previously. ^[1],[2] However, there is a distinct paucity of literature as regards delayed radiation necrosis in diffuse astrocytomas, which is an issue to be addressed because of the imperativeness of differentiating it from relatively non-salvagable tumor-recurrence in diffuse astrocytoma and the subsequent effect on prognosis.

In a prospective randomized phase three trial evaluating low dose (50.4 Gy/28 fractions) versus high dose (64.8 Gy/36 fractions) radiation therapy (RT) for supratentorial low-grade gliomas, the 2-year actuarial incidence of grade 3−5 radiation neurotoxicity (necrosis) was 2.5% with low-dose RT and 5% with high-dose RT. ^[3] In our case, the total dosage of 60 Gy of conventional external beam radiotherapy in 28 fractions was not expected to cause delayed radiation necrosis.

Positron emission tomography with fluorodeoxy-glucose, SPECT with thallium chloride, proton MR spectroscopy and stereotactic biopsy among others, can be used to differentiate recurrence/regrowth of malignant tumors from radionecrosis. ^[4],[5] However, no single technique is a gold standard, as evident in our case, where there was an apparent discordance between MR spectroscopic findings and the final histopathology report.

The treatment options for intracerebral radiation necrosis include surgical decompression and conservative management with corticosteroids. ^[6] Our patient presented with worsening symptoms, so we recommended surgery and the patient subsequently improved.

To conclude, there is scant literature regarding delayed radiation necrosis in diffuse astrocytomas. Radiation necrosis, as evident in our case report too, is known to be a relatively benign entity, which can be treated with good outcomes, and thus, should not be missed out as a differential diagnosis of tumor-recurrence in diffuse astrocytomas, even when it occurs disproportionately delayed.

References

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