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M. Rosenblum
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MA17 - Genetic Drivers (ID 409)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Biology/Pathology
- Presentations: 1
- Moderators:M. Satouchi, G.R. Simon
- Coordinates: 12/07/2016, 14:20 - 15:50, Lehar 1-2
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MA17.01 - Microarray Identification of Genetic Drivers of Brain Metastasis in Lung Adenocarcinoma (ID 3962)
14:20 - 15:50 | Author(s): M. Rosenblum
- Abstract
- Presentation
Background:
Brain metastasis in non-small cell lung cancer (NSCLC) develop in 20-40% of all patients and represent a major cause of NSCLC morbidity and mortality. The mechanisms driving metastatic potential across the blood-brain-barrier remain poorly understood.
Methods:
Affymetrix microarray was performed on RNA extracted from 75 pairs of snap-frozen primary lung adenocarcinoma and matched normal lung tissue. Changes in gene expression from the primary lung adenocarcinomas that did not ever metastasize to brain over up to 15 years of follow up were compared to the lung adenocarcinomas that ultimately seeded a brain metastasis. From these 75 patients, tissue from 5 paired snap-frozen brain metastases was also available and gene expression changes between the primary lung adenocarcinomas and matched brain metastases were investigated to identify genes and pathways of interest in the development of brain metastasis. Affymetrix Transcriptome Analysis Console software was used for data analysis and interpretation with fold changes >2.0 and p-value of <0.05 for significance.
Results:
From the 75 patients 20 (27%) ultimately developed a brain metastasis from their primary lung adenocarcinoma and 55 (73%) were followed long term without development of brain metastasis. Microarray identified 71 genes that were differentially expressed in lung adenocarcinomas that later produced brain metastasis. S100 calcium binding protein, RAP1GAP, GPR160, and immunoglobins were among the upregulated genes in primary lung adenocarcinomas that developed brain metastasis. Within the matched sets of brain metastasis, hierarchical clustering showed clear distinction in expression patterns comparing brain metastasis verses normal lung, as well as primary adenocarcinomas verses normal lung. 267 genes were identified to be significantly differentially expressed between paired brain metastasis and primary lung adenocarcinomas. Significant changes in focal adhesion, angiogenesis, matrix metalloproteinase pathways, and immunoglobulins were found in the brain metastasis compared with the paired primary lung tumor.
Conclusion:
This study represents the largest microarray analysis of snap frozen pairs of primary lung adenocarcinoma and brain metastasis to date. S100 calcium binding protein, RAP1GAP, GPR160 genes, immunoglobulins, and focal adhesion, angiogenesis, and matrix metalloproteinase pathways were among the upregulated genes in primary lung adenocarcinomas that developed brain metastasis.
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P3.01 - Poster Session with Presenters Present (ID 469)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Biology/Pathology
- Presentations: 1
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.01-013 - Case Report of Melanotic Schwannoma: A Challenging Diagnosis Made Clear through Genetic Testing (ID 4943)
14:30 - 15:45 | Author(s): M. Rosenblum
- Abstract
Background:
Melanotic schwannomas (MS) are tumors associated with the Carney complex of hyperpigmentation, myxomas, and endocrine overactivity. They most frequently arise from spinal nerve roots and present a diagnostic challenge due to their lack of characteristic pathologic features. We present the case of an otherwise healthy 35-year-old man who presented with nocturnal dyspnea and ptosis. Imaging identified a large 8.1 x 9.2 x 8.4 cm mass in the right apical posterior mediastinum. Core biopsy was consistent with melanoma, although no primary site could be identified. The patient underwent complete R0 resection of an encapsulated posterior thoracic inlet mass adherent to the sympathetic chain and apical parietal pleura. Surgical pathology showed nests of large pleomorphic epithelioid cells with prominent nucleoli and abundant intracytoplasmic pigment consistent with the initial diagnosis of melanoma. The actual diagnosis of melanontic schwannoma was made only when the tumor was sent for molecular testing and a rare mutation was identified.
Methods:
Oncogene sequencing (UCSF-Syapse) was performed on surgically resected formalin-fixed and paraffin embedded tumor. Single nucleotide variations, copy number changes, and rearrangements were detected using a hybridization-based enrichment assay of approximately 500 oncogenes commonly implicated in the development of neoplasia. Of the genes assayed, entire coding regions were analyzed in 429 genes with additional analysis of selected introns in 42 genes.
Results:
Based on standard hematoxyalin and eosin (H&E) stains as well as S-100 and Melan-A positivity on immunohistochemistry (IHC) stains, the specimen was originally diagnosed as melanoma. The initial diagnosis was also supported by a Ki-67 proliferative index of 15%. Molecular testing uncovered a rare PRKAR1A mutation inconsistent with melanoma and consistent with melanotic schwannoma. No other mutations were identified. PRKAR1A mutations are known to occur in up to 70% of Carney complex patients but have never been known to occur in melanoma.
Conclusion:
Standard techniques of H&E and IHC staining with their potential to misdiagnose two similar tumor histologies are outdated in the context of 21st century technology. Modern precision medicine and molecular diagnostics enable the clear distinction of histologically similar tumors. The speed and low cost of sequencing technology has advanced to recommend its frequent use in cases such as this where a diagnosis is not entirely clear.
