Enlarged piloid astrocytoma of the midbrain: recurrence or pseudoprogression? A clinical case

Piloid astrocytoma (PA) is a glioma that is most frequently encountered in children (WHO grade I). According to most authors, stereotactic radiation (radiotherapy and radiosurgery) is an effective method to control tumor growth in patients with incomplete removal of PA and its recurrence. The authors describe a clinical case of a female patient with PA of the midbrain; during the first 7 months after radiation she showed an obvious enlargement of the tumor, as evidenced by magnetic resonance imaging (MRI), with its further regression without any antitumor treatment. A follow-up of the patient and a regular evaluation of her clinical status and MRI changes, as compared to the similar clinical cases and literature data, may suggest that PA enlargement early after radiotherapy is generally pseudoprogression rather than true progression of the tumor. An understanding of this phenomenon will be able to improve the assessment of radiotherapy results in patients with PA and to rule out unnecessary antitumor treatment in this category of patients.