2021-04-302021-04-302021https://hdl.handle.net/20.500.12503/30474Introduction: Gastrointestinal stromal tumors(GISTs) are rare mesenchymal tumors that originate in the gastrointestinal tract often characterized by the upregulated CD117(c-KIT) proto-oncogene.Histologically they can range from predominantly spindle-shaped(70%),epithelioid-in-character(20%),or a combination of both(10%).GISTs mainly metastasize to the liver(65%)or the peritoneum(21%), whereas metastasis to the lymph nodes(6%),bone(6%), or lung(2%) are significantly rarer.Here, we present a case of a rare metastasis to the lung pleura.Case:A 53-year-old Asian female with a history of type2 diabetes mellitus,hypertension,and hyperlipidemia initially presented to the ED with complaints of increasing shortness of breath.She received a chest x-ray which showed left sided pleural effusion with atelectasis and had a chest tube placed and pleural fluid tapped.She underwent a chest CT with contrast which revealed a left lower lobe mass;however, left lung biopsy showed benign pulmonary parenchyma.Following her visit to the ED,pathology results proved that the pleural effusion was a result of GIST metastasis to the pleura.TNM Staging was completed and was shown to be T4,N1,and cM1.The tumor was found to be C-KITpositive and also revealed an exon11 mutation.She was started on Imatinib after her initial diagnosis,but disease continued to progress the following year and she was switched to Sunitinib.She also underwent thoracotomy,partial pleurectomy,and pleurodesis which improved her breathing.Patient's current treatment plan is Sunitinib 25mg daily and continued follow up with oncology.Conclusion:Ultimately,this atypical presentation should encourage clinicians to consider GIST metastases as a potential diagnosis for patients with a history of recurrent pleural effusions without a known etiology or an epithelioid subtype pathology.enposter