British Journal of Cancer (1999) 80(9), 1322–1331 © 1999 Cancer Research Campaign Article no. bjoc.1999.0525 Comparative genomic hybridization and histological variation in primitive neuroectodermal tumours JC Nicholson1,2, FM Ross1, JA Kohler2 and DW Ellison3 1Wessex Regional Genetics Laboratory, Salisbury, Wiltshire SP2 8BJ, UK; Departments of 2Child Health and 3Pathology, Southampton General Hospital, Southampton SO16 6YD, UK Summary The objective of this study was to test the hypothesis that chromosomal imbalances in central nervous system primitive neuroectodermal tumours (PNETs) reflect site and histology. We used comparative genomic hybridization to study 37 cases of PNET, of which four were cerebral and 31 were medulloblastomas classified histologically as classic (n = 17) or nodular/desmoplastic (n = 14). Tumour immunophenotype was characterized with antibodies to neuroglial, mesenchymal and epithelial markers. Chromosomal imbalances were detected in 28 medulloblastomas (90%), and significant associations between tumour variants and genetic abnormalities were demonstrated. Aberrations suggesting isochromosome 17q were present in eight (26%) medulloblastomas, of which seven were classic variants. None of these cases, or a further six with gain of 17q, showed immunoreactivity for glial fibrillary acidic protein. Loss on 9q was found in six cases (19%), five of them nodular/desmoplastic. Loss of 22 occurred in four (13%), all classic medulloblastomas in young patients with a poor outcome and immunoreactivity for more than one epithelial or mesenchymal marker. Different patterns of imbalance were found in the cerebral PNETs. There were no abnormalities of chromosome 17, but all three cases with imbalance showed losses of 3p12.3–p14. Keywords: medulloblastoma; cerebral PNET; comparative genomic hybridization; isochromosome 17q; monosomy 22; glial fibrillary acidic protein Tumours of the central nervous system (CNS) are the commonest most common, occurring in a third of cases overall (Mertens et al, solid neoplasms of childhood, and primitive neuroectodermal 1994). Other recognized patterns of abnormality have included tumours (PNETs) are the most numerous among these, accounting loss of the X or Y chromosome, trisomy 7, monosomy 22, double for approximately 25% of all childhood brain tumours (Packer, minutes and structural rearrangements, particularly of chromo- 1995). More than 90% of cases of CNS PNET occur in the somes 1, 7 and 11 (Heim and Mitelman, 1995; Bigner et al, 1997). posterior fossa as medulloblastomas. PNETs at other CNS sites Microsatellite analysis has corroborated the existence of chromo- resemble the classic medulloblastoma, which has a propensity for some 17 abnormalities by documenting loss of heterozygosity divergent differentiation along neuro-epithelial lines, manifesting (LOH) on 17p, as well as on chromosomes 9, 10, 11, 16 and 22 as expression of glial fibrillary acidic protein (GFAP) and/or (Blaeker et al, 1996). neuronal proteins or rarely as the presence of scattered ganglion All of these abnormalities result in genetic imbalance and there- cells (Tomlinson et al, 1992; Ellison and Love, 1998). In addition fore make these tumours particularly suitable for study by compar- to the classic medulloblastoma, several variants are recognized in ative genomic hybridization (CGH). Two previous studies (Schütz the World Health Organization classification of CNS tumours: et al, 1996; Reardon et al, 1997) found widely different numbers of desmoplastic medulloblastoma, melanotic medulloblastoma and abnormalities in medulloblastomas using CGH. The aims of this medullomyoblastoma (Kleihues et al, 1993). Desmoplastic medul- study were to screen a series of CNS PNETs, mostly medulloblas- loblastomas account for approximately 20% of medulloblastomas tomas, for chromosomal imbalance as revealed by CGH, to test the and frequently exhibit a nodular architecture in which cells often hypothesis that histological and immunophenotypical differences show a neuronal or glial immunophenotype; these nodular/desmo- among variants of PNET are associated with specific genetic plastic medulloblastomas are considered to form a histological abnormalities, and to assess the prognostic value of any commonly spectrum of tumours, distinct from classic medulloblastomas observed genetic abnormalities. (Giangaspero et al, 1991; Tomlinson et al, 1992). Cytogenetic studies of medulloblastoma and other PNETs have MATERIALS AND METHODS identified several non-random chromosomal aberrations in a high proportion of cases (Biegel et al, 1989; Bhattachajee et al, 1997; Patient group Bigner et al, 1997). Of these, isochromosome 17q [i(17q)] is the All biopsies (n = 39) came from patients (n = 37) attending the Wessex Neurological Centre in Southampton between 1985 and Received 16 November 1998 1997. Some tumour, surplus to diagnostic requirements, was Revised 21 January 1999 stored in each case at –170°C. All specimens used in the study Accepted 27 January 1999 were obtained prior to commencement of treatment, except in Correspondence to: JC Nicholson, Department of Child Health, Mail Point cases 8 and 13. 0021, G Level, Southampton General Hospital, Tremona Road, Southampton Most patients (n = 31) had a medulloblastoma. Of these, 17 SO16 6YD, UK showed classic histology, while the remaining 14 had a 1322 CGH analysis of PNETs 1323 Table 1 Clinical features of PNETs and CGH results Case Age at PNET Metastases Primary Chemotherapy Radiotherapy Survival CGH results diagnosis variant surgical (years) (years) resection 1 19.8 Classic MB No Subtotal No CS 4.8* rev ish enh(5,6,7,12q24,17,18),dim (X,2q14qter,3,8p12q24.1,9p,11,13q13q31, 14q23q31,16q) 2 14.3 Classic MB No Partial Yes CS 8.8* rev ish enh(7,17q),dim(2,8,11p, 12pterq22,13q,17p) 3 8.5 Classic MB No Subtotal Yes CS 3.3 rev ish enh(4p15.3pter,6q23qter, 9p,12q23qter,17q),dim(Y,5q34qter,8p12pter, 17p,18p,20) 4 0.7 Classic MB No Partial No No 0.3 rev ish dim(22) 5 1.6 Classic MB No Partial Yes No 0.3 rev ish enh(17,19q), dim(Yq,11q13.5q23) 6 6.3 Classic MB Spinal Complete Yes CS 1.4 rev ish enh(17q,18),dim(8,17p) 7 9.8 Classic MB Spinal Partial Yes CS 1.7 rev ish enh(17q),dim(Yq,17p) 8 6.5 Classic MB No Subtotal Yes CS 5.1 1st relapse: rev ish enh(1q,4p16,7q, 12q23qter,17q21qter),dim(4q22q28, 4q32qter, 5q33qter,8p21.3pter, 11p11.2p13,16q21qter) 2nd relapse: rev ish enh(1q,4p16,7q, 12q23qter, 17q21qter),dim(Y,4q22q25, 4q32qter, 5q33qter,8p21.3pter,11p, 16q21qter) 9 6.6 Classic MB No Complete Yes CS 2.8* No imbalances 10 3.3 Classic MB No Complete No CS 6.3* rev ish enh(1q,8,17q),dim(4q31qter,17p) 11 24.8 Classic MB Spinal Subtotal No CS 0.3* rev ish enh(10,17q),dim(17p) 12 4.8 Classic MB Spinal Complete No No 0.1 rev ish enh(2p13.3pter,12,17q,18), dim(4q24qter,16q21qter,17p) 13 30.3 Classic MB No Subtotal No CS 3.3 1st relapse: rev ish enh(Xq,3q,6q26q27,9p, 13,15q23qter,18p),dim(Xp,4q31q34, 9q22q34.1,10q21qter,11p14,11q14q22, 14,15q11q15,17p12pter),amp(2q14q21) 14 32.2 Classic MB Not known Biopsy No No 0 rev ish dim(10q,11,17p) 15 5.3 Classic MB No Subtotal Yes CS 1.5 rev ish dim(22) 16 0.3 Classic MB No Biopsy No No 0 rev ish dim(22) 17 0.7 Classic MB Spinal Subtotal Yes Local 1.3 rev ish enh(14),dim(22) 18 9.3 ndMB Spinal Subtotal Yes CS 0.8 no imbalances 19 5.1 ndMB No Subtotal Yes CS 6.4* rev ish enh(4,5,6,7,17q),dim(Y,8,17p) 20 11.2 ndMB No Subtotal No CS 1.3* rev ish enh(1,7,17q),dim(Xq12q25,Y,8,10,11, 13q13q21,14q11.2q13,14q24,15,20) 21 5.9 ndMB No Subtotal Yes CS 1.2* rev ish enh(2,7,15,17q),dim(3,8,10, 11p15pter,21) 22 5.3 ndMB No Subtotal No No 0.1 rev ish enh(7q,8q24,12q24,17q22qter,18, 19pterq12),dim(8p,10q21.3qter,19q13.2qter) 23 12.7 ndMB No Complete Yes CS 8.1* rev ish enh(1q31qter,2,4q21q25,9p,18), dim(4p15.2q13,4q26q32,8,9q22q34,10,16), amp(12p13,13q33) 24 3.6 ndMB No Complete No CS 7.4* rev ish dim(9q21q31) 25 19.6 ndMB No Subtotal No CS 4.5 Primary tumour: rev ish enh(3q),dim(Y) 1st relapse: rev ish enh(3q),dim(11q13q22) 26 22.8 ndMB No Complete No CS 7.2* rev ish dim(X,6q16q24) 27 7.3 ndMB No Complete No CS 1.3* rev ish enh(1q,2,3p14p21,7,9p,10p,13), dim(Xp,3q,4pterq26,5q,8q12qter,9q21.3q22, 10q,11q23qter,14,16,17p,18p),amp(4q28) 28 30.3 ndMB No Subtotal No CS 2.4 rev ish enh(20q),dim(9q22qter,17p) 29 25.6 ndMB Not known Complete No Local 6.4 rev ish enh(15q12q14) 30 27.9 ndMB Bone Partial No CS 5.6 No imbalances 31 4 ndMB No Subtotal No CS 0.9* rev ish enh(3,9p),dim(9q) 32 11.9 GNB No Complete No CS 10.3* rev ish enh(17q),dim(17p) 33 14.1 MmyoB Not known Complete No CS 10.3* rev ish enh(8) 34 8.3 cPNET No Biopsy Yes Palliative 0.6 rev ish enh(X,1,7p,9,13,16p,19,20,22),dim (3,4,5,6,8q13qter,10q11q22,10q24.3qter, 12p12q23,14,15q11q23,16q12q22.1,18q), amp(7p11.2p12,7q21.3q22) 35 2.6 cPNET No Subtotal Yes CS 5.7* rev ish enh(X,1p32pter,1q32qter,2p, 7q33qter),dim(3p12p14,3p21.3pter,5pterq33, 6,7p12p21.1,9p23q32,11,14q24qter) 36 6.4 cPNET Not known Partial No No 0.2 rev ish dim(3p13p21.1) 37 1.1 cPNET No Complete Yes No 0.8 No imbalances Survival: *denotes ongoing remission.