Omental gastrointestinal stromal tumor: Arriving at a diagnosis with therapeutic options in the molecular era

Abstract

Omental extragastrointestinal stromal tumors are rare neoplasms. We present a case of an elderly woman who was found to have a large solid and cystic pelvic mass of presumed ovarian origin with associated omental neovascularity. Histopathologic examination showed a mixed spindled and epithelioid tumor which was essentially negative for c-KIT and positive for smooth muscle markers by immunohistochemistry. A next generation sequencing panel was performed, analyzing the patient’s tumor for actionable mutations in 50 genes commonly associated with human cancers. Identification of a point mutation in PDGFRA enabled accurate diagnosis and provided an option for targeted therapy for this rare tumor.

Keywords

Gastrointestinal stromal tumor / PDGFRA mutation / Molecular diagnostics / Targeted therapy

CONFLICTS OF INTEREST DISCLOSURE

the authors declare no conflicts of interest.

References

[1] Zhao X, Yue C. Gastrointestinal Stromal Tumor. J Gastrointest Oncol. 2012 Sep; 3(3): 189-208. PMid: 22943011.

[2] Miettinen M, Lasota J. Gastrointestinal stromal tumors: pathology and prognosis at different sites. Semin Diagn Pathol. 2006 May; 23(2): 70-83. PMid: 17193820. https://doi.org/10.1053/j.semdp.2006.09.001

[3] Miettinen M, Sobin LH, Lasota J. Gastrointestinal stromal tumors presenting as omental masses-a clinicopathologic analysis of 95 cases. Am J Surg Pathol. 2009 Sep; 33(9): 1267-75. https://doi.org/10.1097/PAS.0b013e3181a13e99

[4] Thorvaldsdóttir H, Robinson JT, Mesirov JP. Integrative Genomics Viewer (IGV): high-performance genomics data visualization and exploration. Brief Bioinform. 2013 Mar; 14(2): 178-192. PMid: 22517427. https://doi.org/10.1093/bib/bbs017

[5] Sah SP, McCluggage WG. DOG1 immunoreactivity in uterine leiomyosarcomas. J Clin Pathol. 2012 Dec 23; 66(1): 40-3. https://doi.org/10.1136/jclinpath-2012-201150

[6] Yamamoto H, Kojima A, Nagata S, et al. KIT-Negative Gastrointestinal Stromal Tumor of the Abdominal Soft Tissue: A Clinicopathologic and Genetic Study of 10 Cases. Am J Surg Pathol. 2011 Sep; 35(9): 1287-1295. PMid: 21836495. https://doi.org/10.1097/PAS.0b013e3182206f15

[7] Rubin BP, Heinrich MC. Genotyping and immunohistochemistry of gastrointestinal stromal tumors: An update. Semin Diagn Pathol. 2015; 32(5): 392-9. PMid: 25766843. https://doi.org/10.1053/j.semdp.2015.02.017

[8] Hirota S, Ohashi A, Nishida T, et al. Gain-of-function mutations of platelet-derived growth factor receptor alpha gene in gastrointestinal stromal tumors. Gastroenterology. 2003 Sep; 125(3): 660-7. https://doi.org/10.1016/S0016-5085(03)01046-1

[9] Corless CL, Schroeder A, Griffith D, et al. PDGFRA mutations in gastrointestinal stromal tumors: frequency, spectrum and in vitro sensitivity to imatinib. J Clin Oncol. American Society of Clinical Oncology; 2005 Aug 10; 23(23): 5357-64. https://doi.org/10.1200/JCO.2005.14.068

[10] Heinrich MC, Corless CL, Demetri GD, et al. Kinase mutations and imatinib response in patients with metastatic gastrointestinal stromal tumor. J Clin Oncol. 2003 Dec 1; 21(23): 4342-9. http://dx.doi.org/10.1200/JCO.2003.04.19