Japanese Journal of Clinical Oncology Advance Access originally published online on December 6, 2005
Japanese Journal of Clinical Oncology 2005 35(12):753-756; doi:10.1093/jjco/hyi197
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© 2005 Foundation for Promotion of Cancer Research
Case Report |
Cytogenetic Confirmation of a Gastrointestinal Stromal Tumor and Ewing Sarcoma/Primitive Neuroectodermal Tumor in a Single Patient
1 Division of Medical Oncology, 2 Division of Orthopedic Oncology, 3 Division of Clinical Laboratory, 4 Division of Diagnostic Radiology, National Cancer Center Hospital, Tokyo, 5 Department of Pathology, Gunma University Graduate School of Medicine, Maebashi, 6 Division of Orthopedic Surgery, Mito Saiseikai Hospital, Mito and 7 Department of Clinical Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan
For reprints and all correspondence: Tadashi Hasegawa, Department of Clinical Pathology, Sapporo Medical University School of Medicine, South 1, West 16, Chuo-ku, Sapporo 060-8543, Japan. E-mail: hasetada{at}sapmed.ac.jp
Received June 30, 2005; accepted October 9, 2005
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Abstract |
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 TOP Abstract INTRODUCTIONCASE REPORTDISCUSSIONReferences |
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We report a rare case in which two tumor entities, a gastrointestinal stromal tumor (GIST) and Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET), with distinct cytogenetic features occurred in a single patient. The patient was a 72-year-old woman. The first tumor was a submucosal gastric tumor and was diagnosed as a low-risk group GIST based on morphological characteristics and the results of an immunohistochemical analysis for c-kit and CD34. Further cytogenetic analysis revealed that this tumor had a point mutation (D842V substitution) in exon 18 of the platelet-derived growth factor receptor alpha gene. The second tumor was found more than 4 years after the appearance of the first tumor. ES/PNET was highly suspected both morphologically and immunohistochemically, and the diagnosis was confirmed by the detection of an EWS rearrangement using a fluorescence in situ hybridization technique. Although the cytogenetic correlations of these two tumors are unclear, accurate histologic recognition is of clinical importance because the treatments for these two tumors differ.
Key Words: gastrointestinal stromal tumor (GIST) • Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) • KIT/c-kit • platelet-derived growth factor alpha (PDGFRA)
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INTRODUCTION |
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TOPAbstractINTRODUCTIONCASE REPORTDISCUSSIONReferences |
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Gastrointestinal stromal tumor (GIST) is the most common non-epithelial neoplasm occurring in the gastrointestinal tract. Most GISTs are KIT (c-kit proto-oncogene protein)-positive, and c-kit tyrosine kinase is rendered constitutively active by mutations (1,2). Approximately 10% of GISTs do not harbor KIT mutations and instead of KIT these GISTs often have a platelet-derived growth factor receptor alpha (PDGFRA)-activating mutation (3). Treatment with the c-kit tyrosine kinase inhibitor imatinib mesylate (Glivec) is of profound clinical utility in the treatment of GISTs and serves as a paradigm for disease-specific molecular-based therapies (4). Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) is a small round cell tumor that occurs predominantly in the bones and soft tissues of children, adolescents and young adults. This malignancy is characterized by the presence of a typical translocation t(11;22) and its variants (5). In recent years, the combined use of systemic chemotherapy and local treatment has increased the long-term survival rates for ES/PNET from <10% (6) to 50–60% or more (7,8).
Multiple primary cancers (MPCs) within one patient are commonly recognized during routine clinical practice and are not unusual (9). Several factors may lead to the development of MPCs, including genetic susceptibility, common exposure status, and treatment effects from radiotherapy and medical agents. Determining the molecular relationship between MPCs is clinically important because this knowledge may have therapeutic implications (10). Associations between GIST and other mesenchymal tumors like GIST with paraganglioma, gastric GIST with pulmonary chondroma and/or paraganglioma (known as Carney's triad), and neurofibromatosis type 1-related GIST have been reported (11).
Here, we report a rare case in which two tumor entities with distinct cytogenetic features—GIST and ES/PNET—existed in a single patient. The accurate diagnosis of these tumor entities was regarded to have an important impact on their clinical management. The diagnosis was confirmed by a cytogenetic analysis.
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CASE REPORT |
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A 72-year-old woman visited a local hospital complaining of epigastralgia. A radiographic examination revealed a 2.6 cm gastric mass, and a malignant tumor was highly suspected. No metastatic lesions were detected at this time. The patient received a curative gastrectomy but did not receive any additional treatments after the operation.
Four years later, the patient noticed lumbago and dulled response of bilateral feet. A magnetic resonance imaging (MRI) scan revealed a heterogeneous 10 cm mass in the retroperitoneum. The mass had invaded a lumbar vertebra and was pressing against the spinal cord. At the same time, a chest CT showed lung metastatic nodules. Determining whether this retroperitoneal lesion was a GIST metastasis or a primary lesion was difficult. An open biopsy was performed, and the patient was referred to the National Cancer Center Hospital (Tokyo, Japan) for further clinical treatment.
Microscopically, each section of the resected gastric submucosal tumor was moderately cellular and consisted of both spindle and epithelioid cells (Fig. 1A). The nuclear atypia was from mild to moderate, and mitosis was rare. The MIB-1 (Ki-67; 1/100; DakoCytomation, Glostrup, Denmark) labelling index was 
5%. Immunohistochemically, most of the tumor cells were strikingly positive for CD34 (My10; 1/100; DakoCytomation) in the cytoplasm and weakly positive for KIT (CD117; 1/100; DakoCytomation) in the cytoplasm (Fig. 1B). The tumor cells were also positive for vimentin (V9; 1/200; DakoCytomation) and SMA (1A4; 1/100; DakoCytomation). Staining for desmin (D33; 1/100; DakoCytomation), S-100 protein (polyclonal antibody; 1/2000; DakoCytomation) and CD99 (O-13/MIC2; 1/50; Signet, Dedham, Massachusetts, USA) was negative. This tumor was subclassified as a low-risk group based on the MIB-1 grading system (12).
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The retroperitoneal tumor showed a sheet-like arrangement of small round cells with homogeneously increased chromatin and clear cytoplasm (Fig. 2A). Sufficient tumor samples were retrieved but no spindle cell component was found. The tumor cells were positive for CD99 and vimentin and negative for KIT, SMA, desmin and CD34 (Fig. 2B). The MIB-1 labelling index was
80%. Based on these findings, an ES/PNET was strongly suspected.
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A cytogenetic analysis was performed to confirm the diagnosis. First, genomic DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissues of the two tumors using a standard proteinase K digestion method. PCR primers were used to amplify exons 9, 11, 13 and 17 of the c-kit gene and exons 12 and 18 of the PDGFRA gene. The primer sequences and PCR methodology were adapted from a previous study (12). This sequencing analysis revealed a missense point mutation at codon 842 (D842V) in exon 18 of the PDGFRA gene in the gastric lesion (Fig. 3). No such mutation was detected in the retroperitoneal lesion. Second, an interphase fluorescence in situ hybridization (FISH) analysis was performed on FFPE tissue sections of the two tumors using a commercially available EWSR1 (22q12) dual color, break-apart rearrangement probe, which was developed recently and extensively tested by VYSIS (http://www.vysis.com) before release. The FISH analysis was performed according to the manufacturer's instructions, as described in a previous study (13). Hybridization signals were visualized with an epifluorescence microscope, and images were captured on a charge-coupled device (CCD) camera. Fifty nuclei that showed both green and orange signals were counted and the percentages of the fused signals were calculated. In cases that nuclei are not overlapping and all areas of both nuclei are not visible, or nuclei are too close together to determine boundaries, the signals were not counted. As a result, at least 10% of the tumor cells from the retroperitoneal tumor showed a split signal pattern of one green and one orange, demonstrating a rearrangement in the EWS gene (Fig. 4). No such signals were detected in tumor cells from the gastric tumor.
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The patient received 40.5 Gy of radiotherapy to the peritoneal region because her right foot was paralysed. She did not receive systemic chemotherapy because of her advanced age. The patient is alive with her disease at the time of writing this paper (follow-up duration, 4 months).
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DISCUSSION |
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TOPAbstractINTRODUCTIONCASE REPORTDISCUSSIONReferences |
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Adult patients with soft tissue tumors have been reported to develop other malignant tumors with a rate of occurrence that is higher than those of the major cancer entities (14). We analysed 406 cases of soft tissue tumors retrospectively and found that 35 (9%) of these tumors appeared in combination with malignancies other than soft tissue tumors (15). Soft tissue tumors combined with other soft tissue tumors are rare, partly because of the rarity of these individual tumors. GIST and ES/PNET are rare tumors arising from mesenchymal tissues. We analysed 145 GISTs and found that 13 tumors (9%) appeared in combination with other malignancies, 11 of which were common cancers such as lung cancer and hepatocellular carcinoma; the remaining two GISTs appeared in combination with a leiomyosarcoma and the ES/PNET described in the present case (unpublished data). Conversely, ES/PNET patients with a second malignancy were extremely rare, excluding patients with therapy-related malignancies. One reason for this is likely the relatively short survival period of patients with ES/PNET.
Initially, the diagnosis of the gastric tumor was based on the results of morphological and immunohistochemical analyses. The peritoneal tumor occurred more than 4 years after the gastric tumor. The latter tumor could have easily been suspected to be a local recurrence or metastasis related to the former tumor. However, we decided to perform an open biopsy for the latter malignancy because the CT and MRI characteristics of the latter tumor differed from those of the former and because the former tumor had been subclassified as belonging to a low-risk group based on the MIB-1 grading system (12), and distant metastases of such tumors are uncommon. A diagnosis of ES/PNET was strongly suspected based on both microscopic and immunohistochemical findings. Further cytogenetic analysis was required because ES/PNET is rare in elderly patients. We also thought that more information on the correlation between these two tumors was desirable.
The cause of MPCs has been suggested in many reports to include chemotherapy, radiotherapy, genetic syndromes, mutated genes and familial syndromes. The two tumors in the present case were clearly caused by mutated genes. One tumor exhibited a point mutation D842V substitution in exon 18 of the PDGFRA gene, whereas the other had an EWS rearrangement resulting from a t(11;22) translocation. Although KIT negative or weakly positive myxoid epithelioid GISTs have been reported to be closely correlated with PDGFRA gene mutations (12), this correlation has also been demonstrated in 25% of mixed-type GISTs (16), as in the present case. Further genetic research may be necessary to determine whether the development of these two tumors in the same individual was coincidental.
In summary, we have reported a rare case in which two tumor entities with distinct cytogenetic features, GIST and ES/PNET, occurred in a single patient. Although the cytogenetic correlations of these two tumors are unclear, accurate histologic recognition is of clinical importance because the treatments for these two tumors differ.
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Acknowledgments |
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This work was supported by Grants-in-Aid for Cancer Research (16-6), and Grants-in-Aid for Clinical Cancer Research and Grants-in-Aid for Cancer Research (14S-4 and -5) from the Ministry of Health, Labor and Welfare, Japan.
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References |
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