Clinicopathological features from long-term observation of a papillary tumor of the pineal region (PTPR): a case report.

Papillary tumor of the pineal region (PTPR) was recently added to the 2007 WHO classification of tumors of the central nervous system as a rare pineal tumor. We present a case of a 17-year-old man who developed a 3-cm pineal tumor that was incompletely excised following two operations. The pathological findings presented were extensive epithelial papillary structures surrounding vessels mimicking "perivascular pseudo-rosettes," leading to a diagnosis of "papillary ependymoma." Subsequently, the residual tumor recurred on three separate occasions. Immunohistochemical studies showed the tumor was positive for cytokeratin 18 (CK 18), microtubule-associated protein (MAP 2), neuron-specific enolase (NSE), neuronal nuclei (NeuN), and transthyretin, consistent with mature neuronal differentiation. Given these findings, the diagnosis of PTPR was made. The patient's survival time of 218 months is the longest reported to date for this tumor.