—  SHORT COURSE #59  —

In Situ Hybridization in Diagnostic Pathology

Case 7 - Anaplastic Oligodendroglioma with Codeletion of 1p and 19q

Ricardo V. Lloyd and Arie Perry


Clinical History
This 35-year old woman underwent a frontal lobe biopsy for an enhancing intraparenchymal neoplasm. She was treated with radiation therapy and did well until 14 years later when imaging abnormalities were once again noted.

Gross Description
The open biopsy obtained by frontal craniotomy in 1987 yielded of a 2 x 2 x 0.4 cm fragment of brain tissue. Stereotactic biopsy of the recurrence in 2001 yielded several needle cores, approximately 1 cm each in length.


Case 7 - Figure 1

Case 7 - Figure 2

Case 7 - Figure 3



Case 7 - Figure 4

Case 7 - Figure 5
GFAP
Case 7 - Figure 6
MIB-1


Case 7 - Figure 7
1p32 (green); 1q42 (pink)
Case 7 - Figure 8
19p13 (green); 19q14 (pink)

Microscopic Description
Sections from the 1987 biopsy revealed a markedly cellular, infiltrative glial neoplasm with both cortical and subcortical involvement. A myxoid / microcystic background was evident in some areas and there were scattered microcalcifications. Perineuronal satellitosis was seen in regions of cortical involvement. Tumor nuclei were mostly round and regular with minimal discernable cytoplasm, though some regions were characterized by a more epithelioid cytology with clear to amphophilic cytoplasm, vesicular nuclei, and prominent nucleoli. The mitotic index was moderate to focally brisk. Tumor vascularity consisted primarily of arborizing, thin-walled capillaries, imparting a "chicken-wire" pattern. However, there was also endothelial proliferation with multilayered vessels containing plump endothelial cells. No necrosis was found. Immunohistochemistry performed retrospectively revealed extensive GFAP positivity, primarily highlighting a thin rim of perinuclear cytoplasm and short, thin processes, morphologically consistent with "gliofibrillary oligodendrocytes". A small subset of tumor cells were p53 immunoreactive and the MIB-1 (Ki-67) labeling index was moderate to focally high.

By comparison, the 2001 "recurrence" appeared less cellular, more pleomorphic and generally more "astrocytic" with hyperchromatic nuclei and variable degrees of eosinophilic cytoplasm. The proliferative index was somewhat lower and radiation effects were evident, including telangiectatic / hyalinized vessels and regions of infarct-like necrosis. The original tumor was considered an anaplastic oligodendroglioma, WHO grade III and was associated with combined 1p and 19q deletions by FISH, evident in the great majority of tumor cells. The recurrence was diagnosed as an anaplastic mixed oligoastrocytoma and demonstrated "relative" 1p and 19q deletions, with many polysomic cells containing 4 copies of the reference probe and 2 copies of the test probe. Based on these genetic results, it was felt that this represented a tumor recurrence rather than a new tumor and that an astrocytic-appearing or polysomic clone had emerged.

Discussion (Modified from Reference [1])
In no other area of brain tumor pathology has FISH proved more clinically valuable than in the genetic profiling of oligodendroglial tumors. Comprising approximately 20-25% of adult gliomas, oligodendrogliomas tend to progress more slowly than astrocytomas, and are associated with longer patient survival [1, 2, 3, 4] . The diagnosis of these tumors is particularly critical given that many anaplastic oligodendrogliomas respond favorably to chemotherapy, especially the PCV regimen (procarbazine, lomustine (CCNU), and vincristine) [3, 5, 6, 7] . Unfortunately, the histologic classification of oligodendroglial neoplasms remains subject to considerable interobserver variability and the oligodendroglial phenotype has expanded over time to include GFAP-positive "minigemistocytes" and "gliofibrillary oligodendrocytes" [8, 9] .

LOH, CGH, and FISH studies have shown that 60-70% of oligodendrogliomas are characterized by a distinctive genetic pattern, consisting of combined deletions of the entire 1p and 19q chromosomal arms [10, 11, 12, 13] . These molecular alterations have potential diagnostic, prognostic, and even therapeutic relevance. For instance, using 1p36 and 19q13.3 LSI FISH probes, Smith et al showed that 1p and particularly combined 1p/19q deletions were highly associated with the oligodendroglial phenotype [13]. They further established that such deletions were associated with prolonged patient survival in pure oligodendrogliomas, irrespective of grade [14]. This favorable association was not detected in astrocytomas or mixed oligoastrocytomas (MOAs) with this molecular signature, though a relatively small number of MOAs were analyzed and this issue remains unresolved [14, 15, 16] . Losses of 19q have also been associated with malignant progression in astrocytomas, though the deletions are often smaller in such cases and 1p is typically not codeleted. Perhaps of greatest clinical relevance, Cairncross et al have shown that allelic loss of 1p was a statistically significant predictor of PCV chemosensitivity, and that combined 1p and 19q loss was associated with both chemosensitivity and longer recurrence-free survival [17]. The mechanism for this enhanced therapeutic responsiveness is poorly understood, though additional studies have shown enhanced radiosensitivity as well, consistent with the findings in the current case [18]. Therefore, it is possible that the combined 1p/19q-losing oligodendrogliomas are also more sensitive to other drugs, such as temozolamide, a currently popular chemotherapeutic agent with less patient toxicity than the PCV regimen. In other words this oligodendroglioma variant may be a better behaving tumor, regardless of the therapeutic approach. Since this is still speculative, clinical trials are needed to address this issue. Nevertheless, sufficient data now exists to support ancillary 1p or 1p/19q testing and a number of labs, including ours, currently offer this by LOH, FISH, or both.

Mixed oligoastrocytomas (MOAs) and other morphologically ambiguous gliomas are a histologically and clinically diverse group of tumors [4]. As with pure oligodendrogliomas, some MOAs respond favorably to PCV chemotherapy [7]. Unfortunately, objective diagnostic criteria are lacking and neuropathologist concordance rates for diagnosing MOA remain low [9]. As a group, survival rates fall somewhere between those of pure astrocytic and oligodendroglial tumors of similar grade, but there is wide individual patient variability [9, 19, 20] . Thus, an obvious hope is that molecular profiling will provide a more clinically useful stratification. In this regard, Maintz et al proposed two genetic subsets of MOA, one exhibiting p53 gene mutations as seen in astrocytomas and another with 1p and 19q deletions, more typical of oligodendrogliomas [21]. Since genetic studies have typically revealed either a more astrocytoma-like or oligodendroglioma-like pattern, it is still debated whether MOAs represent truly mixed tumors or simply pure gliomas, wherein the histogenesis is less obvious. Preliminary data from our lab suggest that "astrocytoma-associated" alterations predict a worse behavior, whereas "oligodendroglioma-associated" alterations or the lack of detectable alterations are associated with improved prognosis [22].

Many other examples of FISH analysis for aneusomy have been reported and a full listing is beyond the scope of this course. However, a couple of other clinically relevant FISH assays recently developed include those designed to detect trisomy 12 in B-cell CLL [23] and polysomies in urothelial carcinomas [24]. In the former study, a commercially available CEP12 probe was utilized on peripheral blood specimens from 82 consecutive patients and the 20% of patients with evidence of trisomy 12 had rapid progression and reduced treatment-free survival. The latter study utilized a newly-developed, commercially available 4-color FISH assay (www.vysis.com) designed to increase the diagnostic yield for urothelial carcinoma in urine cytology specimens. The assay takes advantage of the high frequencies of gains for chromosomes 3, 7, and 17 and loss of the p16 region on 9p21 in urothelial carcinomas, even those in the early stages of development. In a study of 265 patients, Halling et al. found sensitivities of 81% and 58% for FISH and routine cytology, respectively [24]. The specificity for FISH was 96%, as compared to 98% for cytology. This assay has recently received FDA clearance for clinical use in monitoring the recurrence of bladder cancer (www.vysis.com).

References

  1. Fuller CE, Perry A (2002) Fluorescence in situ hybridization (FISH) in diagnostic and investigative neuropathology. Brain Pathol 12:67-86

  2. Shaw EG, Scheithauer BW, O'Fallon J, Tazelaar HD, Davis DH (1992) Oligodendrogliomas: the Mayo Clinic experience. J Neurosurg 76:428-434

  3. Fortin D, Cairncross JG, Hammond RR (1999) Oligodendroglioma: an appraisal of recent data pertaining to diagnosis and treatment. Neurosurg 45:1279-1291

  4. Kleihues P, Cavenee WK (eds) (2000) World Health Organization classification of tumours. Pathology and genetics of tumours of the nervous system. IARC Press, Lyon, France

  5. Cairncross JG Macdonald DR (1988) Successful chemotherapy for recurrent malignant oligodendroglioma. Ann Neurol 23:360-364

  6. MacDonald DR, Gaspar LE, Cairncross JG (1990) Successful chemotherapy for newly diagnosed aggressive oligodendroglioma. Ann Neurol 27:573-574

  7. Glass J, Hochberg FH, Gruber ML, Louis DN, Smith D, Rattner RN (1992) The treatment of oligodendrogliomas and mixed oligodendroglioma-astrocytomas with PCV chemotherapy. J Neurosurg 76:741-745

  8. Kros JM, Van Eden CG, Stefanko SZ, Waayer-Van Batenburg M, van der Kwast TH (1990) Prognostic implications of glial fibrillary acidic protein containing cell types in oligodendrogliomas. Cancer 66:1204-1212

  9. Perry A (2001) Oligodendroglial neoplasms: current concepts, misconceptions, and folklore. Adv Anat Pathol 8:183-199

  10. Reifenberger J, Reifenberger G, Liu L, James CD, Wechsler W, Collins VP (1994) Molecular genetic analysis of oligodendroglial tumors shows preferential allelic deletions on 19q and 1p. Am J Pathol 145:1175-90

  11. Bello MJ, Leone PE, Vaquero J, De Campos JM, Kusak ME, Sarasa JL, Pestana A, Rey JA (1995) Allelic loss at 1p and 19q frequently occurs in association and may represent early oncogenic events in oligodendroglial tumors. Int J Cancer 64:207-210

  12. Kraus JA, Koopmann J, Kaskel P, Maintz D, Brandner S, Louis DN, Wiestler OD, von Deimling A (1995) Shared allelic losses on chromosomes 1p and 19q suggest a common origin of oligodendroglioma and oligoastrocytoma. J Neuropathol Exp Neurol 54:91-95

  13. Smith JS, Alderete B, Minn Y, Borell TJ, Perry A, Mohapatra G, Smith SM, Kimmel D, Yates A, Feuerstein BG, Burger PC, Scheithauer BW, Jenkins RB (1999) Localization of common deletion regions on 1p and 19q in human gliomas and their association with histological subtype. Oncogene 18:4144-52

  14. Smith JS, Perry A, Borell TJ, Lee HK, O'Fallon J, Hosek SM, Kimmel D, Yates A, Burger PC, Scheithauer BW, Jenkins RB (2000) Alterations of chromosome arms 1p and 19q as predictors of survival in oligodendrogliomas, astrocytomas, and mixed oligoastrocytomas. J Clin Oncol 18:636-45

  15. Ino Y, Zlatescu MC, Sasaki H, MacDonald DR, Stemmer-Rachamimov AO, Jhung S, Ramsay DA, von Deimling A, Louis DN, Cairncross JG (2000) Long survival and therapeutic responses in patients with histologically disparate high-grade gliomas demonstrating chromosome 1p loss. J Neurosurg 92:983-990

  16. Kraus JA, Lamszus K, Glesmann N, Beck M, Wolter M, Sabel M, Krex D, Klockgether T, Reifenberger G, Schlegel U (2001) Molecular genetic alterations in glioblastomas with oligodendroglial component. Acta Neuropathol 101:311-320

  17. Cairncross JG, Ueki K, Zlatescu MC, Lisle DK, Finkelstein DM, Hammond RR, Silver JS, Stark PC, Macdonald DR, Ino Y, Ramsay DA, Louis DN (1998) Specific genetic predictors of chemotherapeutic response and survival in patients with anaplastic oligodendrogliomas. J Natl Cancer Inst 90:1473-1479

  18. Bauman GS, Ino Y, Ueki K, Zlatescu MC, Fisher MC, Macdonald DR, Stitt L, Louis DN, Cairncross JG (2000) Allelic loss of chromosome 1p and radiotherapy plus chemotherapy in patients with oligodendrogliomas. Int J Radiat Oncol Biol Phys 48:825-830

  19. Shaw EG, Scheithauer BW, O'Fallon J, Davis DH (1994) Mixed oligoastrocytomas: a survival and prognostic factor analysis. Neurosurgery 34:577-582

  20. Smith JS, Jenkins RB (2000) Genetic alterations in adult diffuse glioma: Occurrence, significance, and prognostic implications. Front Biosci 5:213-231

  21. Maintz D, Fiedler K, Koopmann J, Rollbrocker B, Nechev S, Lenartz D, Stangl AP, Louis DN, Schramm J, Wiestler OD, von Deimling A (1997) Molecular genetic evidence for subtypes of oligoastrocytomas. J Neuropathol Exp Neurol 56:1098-1104

  22. Fuller CE, Schmidt RE, Roth KA, Burger PC, Scheithauer BW, Banerjee R, Perry A (2002) Mixed oligoastrocytomas and other morphologically ambiguous gliomas: a combined histologic and genotypic approach to diagnosis. J Neuropathol Exp Neurol 61:452

  23. Tefferi A, Bartholmai BJ, Witzig TE, Jenkins RB, Li C-Y, Hanson CA, Mesa RA, Phyliky RL (1997) Clinical correlations of immunophenotypic variations and the presence of trisomy 12 in B-cell chronic lymphocytic leukemia. Cancer Genet Cytogenet 95:173-177

  24. Halling KC, King W, Sokolova IA, Meyer RG, Burkhardt HM, Halling AC, Cheville JC, Sebo TJ, Ramakumar S, Stewart CS, Pankratz S, O'Kane DJ, Seelig SA, Lieber MM, Jenkins RB (2000) A comparison of cytology and fluorescence in situ hybridization for the detection of urothelial carcinoma. J Urol 164:1768-1775