_______________________________________________________________________________________________________________________________ 396 https://www.id-press.eu/mjms/index ID Design Press, Skopje, Republic of Macedonia Open Access Macedonian Journal of Medical Sciences. 2019 Feb 15; 7(3):396-399. https://doi.org/10.3889/oamjms.2019.114 eISSN: 1857-9655 Case Report Pulmonary Embolism Masquerading as Severe Pneumonia: A Case Report Alvin Oliver Payus 1* , Rathika Rajah 2 , Dayang Corieza Febriany 1 , Norlaila Mustafa 2 1 Faculty of Medicine and Health Science, Universiti Malaysia Sabah (UMS), Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia; 2 Department of Internal Medicine, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Jalan Yaacob Latif, 56000 Cheras, Kuala Lumpur, Malaysia Citation: Payus AO, Rajah R, Febriany DC, Mustafa N. Pulmonary Embolism Masquerading as Severe Pneumonia: A Case Report. Open Access Maced J Med Sci. 2019 Feb 15; 7(3):396-399. https://doi.org/10.3889/oamjms.2019.114 Keywords: De novo pulmonary embolism; Deep vein thrombosis; Severe pneumonia; Computed tomography of pulmonary angiography *Correspondence: Alvin Oliver Payus. Faculty of Medicine and Health Science, Universiti Malaysia Sabah (UMS), Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia. E-mail: dralvinpayus@ums.edu.my Received: 25-Dec-2018; Revised: 18-Jan-2019; Accepted: 20-Jan-2019; Online first: 10-Feb-2019 Copyright: © 2019 Alvin Oliver Payus, Rathika Rajah, Dayang Corieza Febriany, Norlaila Mustafa. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0) Funding: This research did not receive any financial support Competing Interests: The authors have declared that no competing interests exist Abstract BACKGROUND: De novo pulmonary embolism (DNPE) is a term used when pulmonary embolism (PE) occur in the absence of deep vein thrombosis (DVT). Most DNPE cases occur in a patient who had a recent injury to the chest. CASE PRESENTATION: However, here we report a case of DNPE with a slightly different presentation where there is no preceding trauma and has symptoms that mimic severe pneumonia. He presented with high fever, dyspnoea and pleuritic chest pain. Despite on 10 L of oxygen supplementation via high flow mask and already given bolus intravenous antibiotic, the patient still tachypnoeic and was persistently in type I respiratory failure. His chest X-ray showed consolidative changes. Upon further investigation revealed no evidence of DVT on Doppler ultrasound and normal D-dimer level. Due to the high index of suspicion by the attending physician, PE was suspected and later confirmed with computed tomography pulmonary angiography scan. He was successfully treated with anticoagulation therapy. The objective of this case report is to share the difficult experience of diagnosing PE when the presentation highly atypical and mimics severe pneumonia. CONCLUSION: And with such a masquerading presentation, one can easily miss the diagnosis. To the best of our knowledge, there are very few similar cases reported. Introduction Pulmonary embolism (PE) is a serious medical condition that occurs when a clot usually from the deep vein thrombosis (DVT) dislodged and occluded the pulmonary circulation. It is clinically manifested as shortness of breath, pleuritic chest pain, coughing, orthopnoea, haemoptysis and much other less common presentation [1]. If the PE is massive, the patient can even present with circulatory collapse. When an established PE occurs without any evidence of DVT, the condition is deemed to be called de novo pulmonary embolism (DNPE). A recent study showed that DNPE is not uncommon, and it is associated with a patient who has a history of recent trauma or accident, especially to the chest. However, here we present a patient who developed PE but has no history of recent trauma. Subsequent investigations noted that the patient has no evidence of DVT and any intracardiac clots or vegetations from echocardiography. Therefore, it is deemed suitable for this patient to be labelled as DNPE and will be the centre of the discussion of this case report. Case Report A 70-year old man with underlying hypertension, diabetes mellitus, dyslipidaemia and ischemic heart disease who had undergone multiple percutaneous coronary interventions between the