Pilomyxoid Astrocytoma Presenting With Developmental Regression: A Case Report

Pilomyxoid astrocytoma (PMA) is a subtype of pilocytic astrocytoma (PA). PMA tends to exhibit a more aggressive course compared to PA. We present a case of a two-year-old male with a PMA in the suprasellar region who presented with developmental regression, loss of previously attained milestones such as the ability to hold his neck, walk, and talk, along with hypotonia in all four limbs. Serum cortisol and thyroid-stimulating hormone (TSH) levels were measured to rule out endocrine disturbances and were within normal limits. Magnetic resonance imaging (MRI) of the brain showed a solid lesion in the suprasellar region, extending into the pituitary and interpeduncular fossae, compressing the pituitary gland, and effacing the third ventricle, causing cerebrospinal fluid (CSF) flow obstruction and lateral ventricle dilation. The tumor appears hypointense on T1 and hyperintense on T2, with fluid-attenuated inversion recovery (FLAIR), peripheral contrast enhancement, and no calcification, consistent with PMA. The CSF analysis was negative for malignant cells. Histopathological examination revealed monomorphous bipolar and spindle cells in an angiocentric pattern with a myxoid background, without rosenthal fibers, mitoses, or eosinophilic granular bodies, consistent with PMA but not seen in PA. Immunohistochemistry showed strong positivity for glial fibrillary acidic protein (GFAP) and S100, with a Ki-67 index of 3-4%, indicating a low-grade tumor. The preferred treatment is surgical resection, but due to the tumor's deep location and potential long-term neurological effects, the parents opted against surgery. A ventriculoperitoneal shunt was placed to alleviate CSF flow, following which the child showed mild improvement in symptoms. Treatment of nonresectable astrocytomas was controversial, but gross total surgical resection offers better disease control. Chemotherapy is for patients with recurrence or where total resection of the tumor is not possible, and radiotherapy, though the long-term disease control is good, has a variable visual outcome.