Update: Central nervous system high grade neuroepithelial tumor with BCOR alteration

Central nervous system high grade neuroepithelial tumor with BCOR alteration

Central nervous system high grade neuroepithelial tumor with BCOR alteration (CNS HGNET-BCOR) is a rare entity, identified as a small fraction of tumors previously institutionally diagnosed as so-called CNS primitive neuroectodermal tumors. Their genetic characteristic is a somatic internal tandem duplication in the 3′ end of BCOR (BCOR ITD), which has also been found in clear cell sarcomas of the kidney (CCSK) and soft tissue undifferentiated round cell sarcomas/primitive myxoid mesenchymal tumors of infancy (URCS/PMMTI), and these BCOR ITD-positive tumors have been reported to share similar pathological features.

CNS HGNET-BCOR display pathological overlap with CNS-PNET and other histological entities 1).

The high expression of IGF-2 may be a common feature of HGNET-BCOR and ependymoma and may represent a target for new approaches. Several monoclonal antibodies and TKIs for IGF1R are being tested in preclinical and early phase clinical studies and may become relevant in the management of this new and aggressive tumor entity 2).

High expression of altered BCOR transcripts in CNS HGNET-BCOR tumors suggests a different mechanism from BCOR loss-of-function mutations reported in other malignancies, such as medulloblastoma 3) 4).

Yoshida et al., performed a clinicopathological and molecular analysis of six cases of CNS HGNET-BCOR, and compared them with their counterparts in the kidney and soft tissue. Although these tumors had histologically similar structural patterns and characteristic monotonous nuclei with fine chromatin, CNS HGNET-BCOR exhibited glial cell morphology, ependymoma-like perivascular pseudorosettes and palisading necrosis, whereas these features were not evident in CCSK or URCS/PMMTI. Immunohistochemically, diffuse staining of Olig2 with a mixture of varying degrees of intensity, and only focal staining of GFAP, S-100 protein and synaptophysin were observed in CNS HGNET-BCOR, whereas these common neuroepithelial markers were negative in CCSK and URCS/PMMTI. Therefore, although CNS HGNET-BCOR, CCSK and URCS/PMMTI may constitute a group of BCOR ITD-positive tumors, only CNS HGNET-BCOR has histological features suggestive of glial differentiation. In conclusion, we think CNS HGNET-BCOR are a certain type of neuroepithelial tumor relatively close to glioma, not CCSK or URCS/PMMTI occurring in the CNS 5).

Kirkman et al., describe a pediatric male patient with CNS HGNET-BCOR who developed seeding of the tumor into the site of the surgical wound within months of surgery for resection of a residual posterior fossa tumor.

This case emphasises three important points. First, CNS HGNET-BCOR can be aggressive tumors that necessitate close clinical and radiological surveillance. Second, surveillance imaging in such cases should incorporate the surgical incision site into the field of view, and this should be closely scrutinised to ensure the timely detection of wound site seeding. Third, wound site seeding may still occur despite the use of meticulous surgical techniques 6).

Appay et al., reported in 2017, 3 new CNS HGNET-BCOR cases sharing common clinical presentation and pathologic features. The 3 cases concerned children aged 3 to 7 years who presented with a voluminous mass of the cerebellum. Pathologic features included proliferation of uniform spindle to ovoid cells with fine chromatin associated with a rich arborizing capillary network. Methylation profiling classified these cases as CNS HGNET-BCOR tumors. Polymerase chain reaction analysis confirmed the presence of internal tandem duplications in the C-terminus of BCOR (BCOR-ITD), a characteristic of these tumors, in all 3 cases. Immunohistochemistry showed a strong nuclear BCOR expression. In 2 cases, local recurrence occurred within 6 months. The third case, a patient who received a craniospinal irradiation after total surgical removal followed by a metronomics maintenance with irinotecantemozolomide, and itraconazole, is still free of disease 14 months after diagnosis. In summary, CNS HGNET-BCOR represents a rare tumor occurring in young patients with dismal prognosis. BCOR nuclear immunoreactivity is highly suggestive of a BCOR-ITD. Whether CNS HGNET-BCOR should be classified among the category of “embryonal tumors” or within the category of “mesenchymal, nonmeningothelial tumors” remains to be clarified. Because CNS HGNET-BCOR share pathologic features and characteristic BCOR-ITD with clear cell sarcoma of the kidney, these tumors may represent local variants of the same entity 7).

1)

Sturm D, Orr BA, Toprak UH, Hovestadt V, Jones DTW, Capper D, Sill M, Buchhalter I, Northcott PA, Leis I, Ryzhova M, Koelsche C, Pfaff E, Allen SJ, Balasubramanian G, Worst BC, Pajtler KW, Brabetz S, Johann PD, Sahm F, Reimand J, Mackay A, Carvalho DM, Remke M, Phillips JJ, Perry A, Cowdrey C, Drissi R, Fouladi M, Giangaspero F, Łastowska M, Grajkowska W, Scheurlen W, Pietsch T, Hagel C, Gojo J, Lötsch D, Berger W, Slavc I, Haberler C, Jouvet A, Holm S, Hofer S, Prinz M, Keohane C, Fried I, Mawrin C, Scheie D, Mobley BC, Schniederjan MJ, Santi M, Buccoliero AM, Dahiya S, Kramm CM, von Bueren AO, von Hoff K, Rutkowski S, Herold-Mende C, Frühwald MC, Milde T, Hasselblatt M, Wesseling P, Rößler J, Schüller U, Ebinger M, Schittenhelm J, Frank S, Grobholz R, Vajtai I, Hans V, Schneppenheim R, Zitterbart K, Collins VP, Aronica E, Varlet P, Puget S, Dufour C, Grill J, Figarella-Branger D, Wolter M, Schuhmann MU, Shalaby T, Grotzer M, van Meter T, Monoranu CM, Felsberg J, Reifenberger G, Snuderl M, Forrester LA, Koster J, Versteeg R, Volckmann R, van Sluis P, Wolf S, Mikkelsen T, Gajjar A, Aldape K, Moore AS, Taylor MD, Jones C, Jabado N, Karajannis MA, Eils R, Schlesner M, Lichter P, von Deimling A, Pfister SM, Ellison DW, Korshunov A, Kool M. New Brain Tumor Entities Emerge from Molecular Classification of CNS-PNETs. Cell. 2016 Feb 25;164(5):1060-1072. doi: 10.1016/j.cell.2016.01.015. PubMed PMID: 26919435; PubMed Central PMCID: PMC5139621.
3)

Jones DT, Jäger N, Kool M, Zichner T, Hutter B, Sultan M, Cho YJ, Pugh TJ, Hovestadt V, Stütz AM, Rausch T, Warnatz HJ, Ryzhova M, Bender S, Sturm D, Pleier S, Cin H, Pfaff E, Sieber L, Wittmann A, Remke M, Witt H, Hutter S, Tzaridis T, Weischenfeldt J, Raeder B, Avci M, Amstislavskiy V, Zapatka M, Weber UD, Wang Q, Lasitschka B, Bartholomae CC, Schmidt M, von Kalle C, Ast V, Lawerenz C, Eils J, Kabbe R, Benes V, van Sluis P, Koster J, Volckmann R, Shih D, Betts MJ, Russell RB, Coco S, Tonini GP, Schüller U, Hans V, Graf N, Kim YJ, Monoranu C, Roggendorf W, Unterberg A, Herold-Mende C, Milde T, Kulozik AE, von Deimling A, Witt O, Maass E, Rössler J, Ebinger M, Schuhmann MU, Frühwald MC, Hasselblatt M, Jabado N, Rutkowski S, von Bueren AO, Williamson D, Clifford SC, McCabe MG, Collins VP, Wolf S, Wiemann S, Lehrach H, Brors B, Scheurlen W, Felsberg J, Reifenberger G, Northcott PA, Taylor MD, Meyerson M, Pomeroy SL, Yaspo ML, Korbel JO, Korshunov A, Eils R, Pfister SM, Lichter P. Dissecting the genomic complexity underlying medulloblastoma. Nature. 2012 Aug 2;488(7409):100-5. doi: 10.1038/nature11284. PubMed PMID: 22832583; PubMed Central PMCID: PMC3662966.
4)

Pugh TJ, Weeraratne SD, Archer TC, Pomeranz Krummel DA, Auclair D, Bochicchio J, Carneiro MO, Carter SL, Cibulskis K, Erlich RL, Greulich H, Lawrence MS, Lennon NJ, McKenna A, Meldrim J, Ramos AH, Ross MG, Russ C, Shefler E, Sivachenko A, Sogoloff B, Stojanov P, Tamayo P, Mesirov JP, Amani V, Teider N, Sengupta S, Francois JP, Northcott PA, Taylor MD, Yu F, Crabtree GR, Kautzman AG, Gabriel SB, Getz G, Jäger N, Jones DT, Lichter P, Pfister SM, Roberts TM, Meyerson M, Pomeroy SL, Cho YJ. Medulloblastoma exome sequencing uncovers subtype-specific somatic mutations. Nature. 2012 Aug 2;488(7409):106-10. doi: 10.1038/nature11329. PubMed PMID: 22820256; PubMed Central PMCID: PMC3413789.
5)

Yoshida Y, Nobusawa S, Nakata S, Nakada M, Arakawa Y, Mineharu Y, Sugita Y, Yoshioka T, Araki A, Sato Y, Takeshima H, Okada M, Nishi A, Yamazaki T, Kohashi K, Oda Y, Hirato J, Yokoo H. CNS high-grade neuroepithelial tumor with BCOR internal tandem duplication: a comparison with its counterparts in the kidney and soft tissue. Brain Pathol. 2017 Dec 11. doi: 10.1111/bpa.12585. [Epub ahead of print] PubMed PMID: 29226988.
6)

Kirkman MA, Pickles JC, Fairchild AR, Avery A, Pietsch T, Jacques TS, Aquilina K. Early wound site seeding in a patient with CNS high-grade neuroepithelial tumor with BCOR alteration: A case report. World Neurosurg. 2018 May 30. pii: S1878-8750(18)31112-4. doi: 10.1016/j.wneu.2018.05.158. [Epub ahead of print] PubMed PMID: 29859355.
7)

Appay R, Macagno N, Padovani L, Korshunov A, Kool M, André N, Scavarda D, Pietsch T, Figarella-Branger D. HGNET-BCOR Tumors of the Cerebellum: Clinicopathologic and Molecular Characterization of 3 Cases. Am J Surg Pathol. 2017 Sep;41(9):1254-1260. doi: 10.1097/PAS.0000000000000866. PubMed PMID: 28704208.

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