Purpose: Extra-central nervous system (extra-CNS) metastases are relatively unknown failure patterns in medulloblastoma. The aim of this study was to analyse epidemiological, clinical and aetiopathological aspects of these extra-CNS localisations.
Patients and methods: Extra-CNS metastases were retrospectively identified in patients treated in the department of radiation therapy at Salah-Azaïz institute (ISA) for medulloblastoma. These metastases were diagnosed as extra-CNS for all secondary localisations not related to other tumour aetiology. Aetiopathological aspects are discussed with a literature review.
Results: Among 103 patients treated and followed-up in the department of radiation therapy of ISA from 1970 to 1992, 8 developed extra-CNS metastases (7.7%). Age at diagnosis of primitive tumour varied from 3 to 23 years. Sex ratio was 1. Primitive tumour treatment was: complete surgical resection in 4 patients with preoperative cerebrospinal fluid shunting in two, cerebrospinal axis irradiation in 7 patients and a cerebral-limited irradiation in 1. Two patients received chemotherapy for their initial treatment (systemic in one case and intrathecal in the other). The mean free-interval from diagnosis of primitive tumour to extra-CNS metastases was 23 months, varying from 8 to 53 months. These metastases were located in the liver (1 case), cervical lymph nodes (2 cases), bone marrow (1 case) and bone (2 cases). Two patients had multiple metastases: bone and bone marrow (in one), lung, pleura, cervical lymph node and bone localisations (in one). Treatment of these metastases was: chemotherapy in 5 cases, chemotherapy and radiation in one, radiation therapy in one and 2 patients were given only supportive care treatment. All patients died or are in progressive disease in less than one year from the diagnosis of extra-CNS metastases.
Conclusion: Extra-CNS metastases are not rare and have a poor prognosis. The most commonly involved sites are bone, cervical lymph nodes and bone marrow. A complete work-up at initial diagnosis is recommended to screen early metastases. Literature review showed that histopathologic grading might help to identify groups at risk.