en Hematology Hematology case report case report <span style="font-family:Times New Roman;"><span style="font-size:12pt"><span style="line-height:14pt"><span new="" roman="" times=""><b><i><span style="font-size:10.0pt"><span style="color:blue">Background</span></span></i></b><i><span style="font-size:10.0pt"><span style="color:blue">: </span></span></i><span style="font-size:10.0pt">Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has spread globally becoming a pandemic. The clinical manifestations of COVID-19 vary from asymptomatic to symptomatic disease. Hematologic manifestation which is commonly found in COVID-19 patients is thrombocytopenia whereas thrombocytosis is rarely reported. </span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:14pt"><span new="" roman="" times=""><b><i><span style="font-size:10.0pt"><span style="color:blue">Case Presentation:</span></span></i></b><span style="font-size:10.0pt"> We report a case of a 55-year-old woman with one week history of fever which spike along the day, dry cough, anosmia, nausea, epigastric pain and loss of appetite. She lived in local transmission area. The patient was diagnosed as mild suspected COVID-19 and confirmed with nasopharyngeal and oropharyngeal swab test (positive result). On admission, the number of platelet count was within normal limit but progressively increased exceeding 1000 x10⁹/L accompanied by worsening of the clinical condition. Interestingly, to our knowledge, no such case has ever been reported. In this study, we will discuss the possible mechanisms of its changes.</span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:14pt"><span new="" roman="" times=""><b><i><span style="font-size:10.0pt"><span style="color:blue">Conclusions:</span></span></i></b><span style="font-size:10.0pt">&nbsp; COVID-19 can present with extreme thrombocytosis. Thus, monitoring the platelet count during hospitalization can be helpful for anticipating worsening conditions and progression of COVID-19.</span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:14pt"><span new="" roman="" times=""><span style="font-size:10.0pt"></span></span></span></span><br> &nbsp;</span> COVID-19, SARS-CoV-2, hematologic manifestations, thrombocytosis, platelet count 289 294 http://caspjim.com/browse.php?a_code=A-10-2464-1&slc_lang=en&sid=1 Cathleen Kenya cathleenkenya@gmail.com 100319475328460035697 100319475328460035697 Yes Regional Public Hospital of Kramat Jati, Jakarta, Indonesia Nur Chandra Bunawan nur.chandra86@gmail.com 100319475328460035698 100319475328460035698 No COVID-19 Task Force in Regional Public Hospital of Kramat Jati, Jakarta, Indonesia Hardijatmo Muljo Nugroho hardijatmomn@gmail.com 100319475328460035699 100319475328460035699 No COVID-19 Task Force in Regional Public Hospital of Kramat Jati, Jakarta, Indonesia Annisa Dian Harlivasari harlivasari@gmail.com 100319475328460035700 100319475328460035700 No COVID-19 Task Force in Regional Public Hospital of Kramat Jati, Jakarta, Indonesia Edgar David Sigarlaki edgardavidsigarlaki@gmail.com 100319475328460035701 100319475328460035701 No Regional Public Hospital of Kramat Jati, Jakarta, Indonesia Ikhwan Rinaldi ikhwanrinaldi@gmail.com 100319475328460035702 100319475328460035702 No Division of Hematology and Medical Oncology, Department of Internal Medicine, Faculty of Medicine Universitas Indonesia – dr. Cipto Mangunkusumo Hospital, Jakarta, Indonesia