Introduction. Mutations of the APC (adenomatous polyposis coli) gene correlate mainly with familial adenomatous polyposis (FAP), but can occasionally be pathogenic for medulloblastoma (MBL) WNT subtype as well, the course of which has only recently been described. Methods. We retrospectively retrieved all patients with documented germline APC mutations and a centrally-reviewed diagnosis of MBL to examine the outcome of their MBL, late effects of its treatment, and further oncological events. Results. Between 2007-2016 we diagnosed and treated 6 patients, all with a pathogenic APC variant mutation, who all had MBL, classic histotype. None had metastatic disease. All patients were in complete remission a median 65 months after treatment with craniospinal irradiation at 23.4 Gy, plus a boost on the posterior fossa/tumor bed up to 54 Gy, followed by cisplatin/carboplatin, lomustine and vincristine for a maximum of 8 courses. Five of 6 diagnostic revised MRI were suggestive of the WNT molecular subgroup typical aspects. Four of 6 patients had a positive family history of FAP, while gastrointestinal symptoms prompted its identification in the other 2 cases. Four patients had developed other tumors (desmoid, MELTUMP, melanoma, pancreatoblastoma, thyroid Tir3) from 5 to 7 years after MBL. Discussion. Our data confirm a good prognosis for patients with MBL associated with FAP. Patients’ secondary tumors may or may not be related to their syndrome or treatment, but warrant adequate attention when planning shared guidelines for these patients.