Intermediate pilomyxoid astrocytoma and diencephalic syndrome: imaging findings.

Pilomyxoid astrocytoma, an entity described as a histological variant of pilocytic astrocytoma, is a rare primary tumor of the central nervous system. It is usually located in the hypothalamic-chiasmatic area, affecting children with a mean age of 10 months. It has a high rate of recurrence and cerebrospinal fluid dissemination, which may be present throughout the neuroaxis. Due to its topography, it may present developmental delay in childhood and diencephalic syndrome, characterized by extreme weight loss, lack of fat accumulation, hyperactivity, euphoria and alertness. Magnetic resonance imaging has an important role in its diagnosis, staging and follow-up of pilomyxoid astrocytoma. However, for a definitive diagnosis, anatomopathology is particularly important to differentiate it from pilocytic astrocytoma. Some cases, as in this present one, have simultaneous histological features of pilocytic and pilomyxoid astrocytomas, constituting a group called intermediate pilomyxoid astrocytoma. Surgery is the best treatment option and it usually requires adjuvant therapy.