Intermediate Pilomyxoid Astrocytoma in the Cerebellum of a 5-Year-Old Boy.

Intermediate pilomyxoid tumors (IPTs) were defined by the presence of some features typical of pilomyxoid astrocytoma (PMA) in combination with features that could be considered more consistent with pilocytic astrocytoma (PA). PMA is rare in the cerebellum. And, IPT in the cerebellum is rarer than PMA. To our knowledge, only 2 reports have described IPT in the cerebellum. A 5-year-old boy had nausea and vomiting. Computed tomography revealed a large, round, low-density tumor in the cerebellar vermis area. On enhanced magnetic resonance imaging (MRI), the tumor showed inhomogeneous diffuse enhancement; the central portion showed homogenous enhancement, while the peripheral portion showed inhomogeneous enhancement. The patient underwent a midline suboccipital craniotomy, and gross total resection was performed. The tumor was gray-colored, rubbery hard, and severely hemorrhagic with a clear boundary. On pathologic examination, the combined features of both PA and PMA were retrospectively indicative of an IPT. The patient was symptom-free for 18 months, with no evidence of tumor recurrence on MRI. More observation and further studies on PMA and IPT are required to determine the most appropriate treatment for these tumors.