Uncommon presentation of medulloblastoma

Introduction: Medulloblastoma. commonly occurs in children as a midline pos terior fossa mass arising from the vermis, which appears as a hyperdense, h omogeneously enhancing mass on CT scan and is associated with the clinical profile of posterior fossa syndrome. This unique clinico-radiological patte rn is considered 'typical', but then medulloblastomas do not follow the typ ical clinicoradiological pattern in a significant number of cases. Patients : Out of the 42 cases of medulloblastoma operated on at SGPGIMS from 1988 t o 1998, 29 cases were retrospectively and 13 cases were prospectively studi ed to detect the atypical clinico-radiological features. The typical radiol ogical feature of a hyperdense homogeneously enhancing mass was seen in onl y 23 of the 42 patients, while 5 patients had hypodense nonenhancing masses , 13 had cystic changes, and 6 patients had calcifications in their tumours . Three patients presented with tumours in a very unusual location, i.e. th e cerebellopontine angle cistern. Results: During follow-up, which ranged f rom a minimum period of 1 year to a maximum of 9 years, patients came back with metastases at very unusual sites. There were 5 cases of metastases in the frontal and sub-frontal area (developed between 5 months and 5 years fo llowing surgery), and I patient developed a cervical intramedullary metasta sis. Two patients developed abdominal metastases and ascites 2 years after definitive surgery and ventriculo-peritoneal shunting. Each of these 2 pati ents, however, had received a full course of craniospinal irradiation follo wing surgery. Thus, we had a number of cases with an unusual clinical, radi ological and metastatic pattern.