CASE 2209 Published on 16.08.2005

Anaplastic astrocytoma: a case of late-developed secondary neoplasm after radiation for childhood leukemia

Section

Neuroradiology

Case Type

Clinical Cases

Authors

Albrecht L, Breitsprecher R, Aschmetat S, Kirsch M, Hosten N

Patient

21 years, male

Categories
No Area of Interest ; Imaging Technique CT, MR, MR, CT, MR
Clinical History
A 21-year-old male patient presented with seizures, a right facial paralysis, secondary aphasia and gait disorder. Nine years ago he had been treated for a high-risk T-cell acute lymphoblastic lymphoma.
Imaging Findings
The patient presented with seizures, a right facial paralysis, secondary aphasia and gait disorder. Nine years ago he had been treated for a high-risk T-cell acute lymphoblastic lymphoma with a standard protocol (COALL chemotherapy and high voltage radiation therapy [9 MeV] of the head). Computed tomography (Cti high speed, GE) and MRI (Magnetom Impact Expert, Siemens, 1.0T) were performed, which demonstrated the presence of a lesion located in the temporo-parietal region. The enhancement was slight and peripheral, and the margins were ill-defined (Fig. 1). Stereotactic biopsy confirmed anaplastic astrocytoma WHO III°. The patient's neurological condition worsened and a repeat radiation therapy became necessary. A surgical approach seemed not promising. The MRI images showed an increase in the size of the extremely dishomogeneous lesion, and one enhancing nodule was visible next to the biopsy hole. Extensive perifocal oedema and a midline shift to the right were further findings (Fig. 2a, b). Anti-oedematous therapy improved the patient's symptoms. Radiation therapy was continued with a lesser target and lower single doses up to 49.8 Gy. The patient recovered completely and was released from the hospital. He continued with temozolomit chemotherapy. An impressive decrease of tumour and oedema was seen on MRI (Fig. 3a, b). Five months later the patient developed another major seizure, aphasia and right-sided hemiparesis. CT and MRI demonstated the presence of a bilateral periventricular mass with an extensive enhancement (Fig. 4a, b). These imaging findings strongly suggested the diagnosis of either radionecrosis or recurrency of astrocytoma. Despite a poor prognosis, another course of radiation therapy led to complete recovery for eight months. The later bilaterally and periventricularly located contrast-enhanced lesion was assumed to be either radionecrosis or the recurrency of astrocytoma.
Discussion
Cerebral irradiation therapy is part of prevention and treatment of meningeal leukemia. In children with acute lymphoblastic leukemia (ALL), it improves survival rates. The number of cured survivors of this disease is increasing (1). This is one reason why secondary malignancies are now more often seen. Central nervous system tumours such as astrocytoma have been found to be the most common secondary malignancy in these patients (1, 2). In 1991, Salvati and coauthors published a review of the literature concerning radiation-induced gliomas. Among 73 cases during a 40-year period 28 patients had had radiation therapy for childhood ALL. Fourteen of them developed secondary astrocytoma of the brain (2). Because of the small number of cases it is not really clear whether astrocytoma is a radiation-induced entity or whether it is due to a genetic defect in the group of ALL patients (3). Nevertheless, the criteria for a radiation-induced pathogenesis are fulfilled if (1) astrocytoma develops in the radiation-targeted area and (2) if the secondary malignancy occurs late after radiation therapy. The time interval that is considered to be typical ranges from 4.5 to 11 years. Prognostic factors for the treatment of astrocytomas (both de novo and radiation-induced) have been evaluated. The age of the patient, performance status, duration of symptoms, the extent of neurosurgical tumour removal and the tumour grade have proved to be limiting factors (4). Neurosurgery is basic for histopathological diagnosis and grading of the tumour. Nevertheless, prognosis in the case of grade IV anaplastic astrocytoma remains poor despite multimodal therapy. Two-year survival rates of 4%–10% and a five-year survival rate of 0% are typical. The data are somewhat better for grade III astrocytoma where 20%–45% of patients survive for two years and 18%–19% of patients survive for five years (3, 4). Radiation therapy still remains the most important part of therapeutic strategies. Focal irradiation therapy is preferred to whole brain radiation. The total dose usually does not exceed 60 Gy. The radiosensitizers have not fulfilled the expectations and combined chemotherapy does not improve survival rates. One reason is a relapse of the astrocytoma in the radiation target. Interestingly, this appears in 90% in the high-dose area of the radiation field (4). The treatment options for recurrent diseases are then limited. They range from surgery to another course of radiation therapy targeted at the area of contrast enhancement. Survival can thus be prolonged for another 7–12 months. The imaging techniques have improved significantly in the last two decades. In low-grade astrocytomas, computed tomography shows a hypodense core (necrotic area) surrounded by a contrast-enhanced region that consists of active tumour tissue. This is surrounded by a hypodense oedema in untreated patients. MRI shows a more heterogeneous tumour pattern in T2WI. Blurry borders characterize the more infiltrative aspects of high-grade astrocytoma (5). In the present case, the appearance of the lesion changed after radiation therapy. Initially, CT and MRI findings were highly suggestive of glioma. After complete remission in the cerebral location, the pattern, shape and localization were very uncharacteristic of astrocytoma. The recurrence of anaplastic astrocytomas after brain irradiation is common. Therefore, this possibility should be considered by the radiologist even if the appearance of the tumour on imaging studies is uncharacteristic and suggests other entities such as ventriculitis or lymphoma.
Differential Diagnosis List
Anaplastic astrocytoma.
Final Diagnosis
Anaplastic astrocytoma.
Case information
URL: https://www.eurorad.org/case/2209
DOI: 10.1594/EURORAD/CASE.2209
ISSN: 1563-4086