LAUSR

Pineoblastoma (PB) is a CNS embryonal tumor of childhood with propensity to metastasize and a 5-year overall survival of 61% [5]. Originating from the pineal gland, PBs carry molecular profiles distinct from medulloblastomas (MBs), the most frequent embryonal tumors that by definition are located in the posterior fossa [2]. Based on methylation profiling, independent studies have identified biologically and clinically relevant subgroups in PB, driven by discrete genomic alterations [4, 5, 7]. In addition to tumors comprising these bona fide PB subgroups, rare outliers have anecdotally been described. Here, we present a multi-institutional series of patients (n = 7) with WNTactivated embryonal tumors epicentered at the pineal region, including three unreported patients and four that had been briefly described [4, 5, 8]. Findings from DNA methylation array, tumor sequencing, and immunohistochemistry were reported. Clustering and copy-number analysis of methylation profiles were performed as previously described, adopting a radiographically and molecularly verified in-house cohort of MB and PB as reference [5]. Among the 7 patients, 4 were male, and the median age of diagnosis was 15 years (Supplementary Table 1). MRI revealed tumor centering at the pineal gland in five patients, and the posterior aspect of the thalamus abutting the third ventricle in 2 (Fig. 1a). No posterior fossa lesion was present. Six of the patients had localized disease, while 1 had a metastatic focus at the internal auditory canal (Supplementary Fig. 1a). Three patients underwent gross or near-total resection, one had subtotal resection and three had biopsy. Histology of all tumors were compatible with CNS embryonal tumors. Surprisingly, methylation profiling revealed that 6 samples clustered with WNT-activated medulloblastoma (MB-WNT), while 1 sample had no matching entity (Fig. 1b Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s0040 1-020-02208 -9) contains supplementary material, which is available to authorized users.