Frequent Clinical and Radiological Progression of Optic Pathway/Hypothalamic Pilocytic Astrocytoma in Adolescents and Young Adults

Most cases of optic hypothalamic pilocytic astrocytoma (OHPA) develop during childhood, so few cases of histologically verified OHPA have been described in adolescents and young adults (AYA). To elucidate the clinical features of OHPA with histological verification in AYA, we reviewed the clinical and radiological finding of OHPA treated at our institute from January 1997 and July 2017. AYA are aged between 15 and 39 years. The clinical courses of 11 AYA patients with optic hypothalamic glioma (OHG) without neurofibromatosis type 1 were retrospectively reviewed. About six patients were diagnosed in childhood and followed up after 15 years of age, and five patients developed OHPA during AYA. Histological diagnosis, verified at initial presentation or recurrence, was pilocytic astrocytoma in 10 and pilomyxoid astrocytoma in one. After initial treatment including debulking surgery and/or chemotherapy, tumor progression occurred 16 times in seven patients as cyst formation, tumor growth, and intratumoral hemorrhage. Five of 10 patients suffered deterioration of visual function during AYA. One of 10 cases had endocrinopathies requiring hormone replacement at last follow-up examination. In conclusion, histological diagnoses of OHG before and in AYA were pilocytic astrocytoma or pilomyxoid astrocytoma. Both pediatric and AYA-onset OHPA demonstrate high incidences of tumor progression and visual dysfunctions in AYA, so that long-term follow up is essential after the completion of treatment for pediatric and AYA-onset OHPA. The optimal timing of debulking surgery and radiation therapy should be established to achieve the long-term tumor control and to preserve the visual function.