The tumor described in this report was unique because of its involvement with a posterior fossa spontaneous hemorrhage in a pediatric patient; such a case has never been previously described in cases of pilomyxoid astrocytomas and also rarely found in those of pilocytic astrocytomas. This report studied a rare case of posterior fossa pilomyxoid astrocytoma (PMA) with critical and dangerous spontaneous hemorrhage. A 7-year-old girl appeared at the outpatient clinic with sudden headache and vomiting. The patient underwent gross total tumor resection via suboccipital Medline approach, and no evidence of residual or recurrent tumor was found on magnetic resonance images at two follow-up examinations which were respectively conducted 1 and 5 months after resection. In this report, the authors reviewed the literature and discussed the clinical features and treatment of pilomyxoid astrocytoma. It is important to distinguish this tumor variant from the more indolent pilocytic astrocytoma.