Dedifferentiated gastrointestinal stromal tumour with features mimicking malignant PEComa/alveolar soft part sarcoma: An unusual type of morphological transformation following imatinib treatment
{"title":"Dedifferentiated gastrointestinal stromal tumour with features mimicking malignant PEComa/alveolar soft part sarcoma: An unusual type of morphological transformation following imatinib treatment","authors":"Kankanamage Malinda Amesh Karasinghe, Kesavan Sittampalam","doi":"10.1016/j.ehpc.2020.200457","DOIUrl":null,"url":null,"abstract":"<div><p>Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Dedifferentiation is a rare phenomenon in GISTs, most often following long-term Imatinib therapy and less frequently in de-novo fashion. According to the literature, the process of dedifferentiation is likely associated with genetic instability, rather than a result of acquisition of novel mutations in the common driver oncogenes. However, the exact underlying molecular basis of dedifferentiation is not well-established. Dedifferentiated GISTs show anaplastic features with loss of immunoreactivity for CD117 and DOG1. In this report, we present a rare and unique case of dedifferentiated metastatic GIST with a very unusual malignant PEComa/alveolar soft part sarcoma-like morphology. The molecular findings of our case also support the concept that dedifferentiation of GIST is independent of acquisition of additional novel mutations in the common driver oncogenes.</p></div>","PeriodicalId":38075,"journal":{"name":"Human Pathology: Case Reports","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ehpc.2020.200457","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Human Pathology: Case Reports","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214330020301061","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"Medicine","Score":null,"Total":0}
引用次数: 0
Abstract
Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Dedifferentiation is a rare phenomenon in GISTs, most often following long-term Imatinib therapy and less frequently in de-novo fashion. According to the literature, the process of dedifferentiation is likely associated with genetic instability, rather than a result of acquisition of novel mutations in the common driver oncogenes. However, the exact underlying molecular basis of dedifferentiation is not well-established. Dedifferentiated GISTs show anaplastic features with loss of immunoreactivity for CD117 and DOG1. In this report, we present a rare and unique case of dedifferentiated metastatic GIST with a very unusual malignant PEComa/alveolar soft part sarcoma-like morphology. The molecular findings of our case also support the concept that dedifferentiation of GIST is independent of acquisition of additional novel mutations in the common driver oncogenes.