This case was reported in a literature article and described the occurrence of weakness in a 45-year-old male patient who received Influenza vaccine. The patient's past medical history included ex-smoker. Concurrent medical conditions included lung adenocarcinoma metastatic. On an unknown date, the patient received Influenza vaccine (unknown). On an unknown date, 2 days after receiving Influenza vaccine, the patient experienced weakness (serious criteria hospitalization), exertional dyspnea (serious criteria hospitalization), shortness of breath (serious criteria hospitalization), anxiety, tachypnea (serious criteria hospitalization), sinus tachycardia (serious criteria hospitalization), effusion pericardial (serious criteria GSK medically significant), pleural effusion and pericardial tamponade (serious criteria GSK medically significant). On an unknown date, the outcome of the weakness, exertional dyspnea, shortness of breath, anxiety, tachypnea, sinus tachycardia, effusion pericardial, pleural effusion and pericardial tamponade were unknown. It was unknown if the reporter considered the weakness, exertional dyspnea, shortness of breath, anxiety, tachypnea, sinus tachycardia, effusion pericardial, pleural effusion and pericardial tamponade to be related to Influenza vaccine. Additional information received: This case was reported in a literature article and it described the occurrence of a lung adenocarcinoma in a 45-year-old male subject who had been vaccinated with an unspecified influenza vaccine (manufacturer unknown). The subject worked as an engineer. He was a former smoker. No further information on the subject's medical history, concurrent medical conditions or concomitant medication was provided. On unspecified date, the subject received an unspecified influenza vaccine (dosage, administration route and site unknown; batch number not provided). On an unspecified date, two days after the vaccine, the subject started complaining of weakness and dyspnoea on exertion while hiking with his family. He was transferred to an emergency unit 1 week later as he had become increasingly short of breath while at work. Upon clinical examination the subject was anxious without acute distress, his blood pressure was 102/71, his oxygen saturation on room air was 96%, and he was tachypneic (23 rpm) and tachycardic (120 bpm). He did not present neck vein distension and his chest examination was clear bilaterally with decreased sound on the base of the right lung. Cardiac examination revealed tachycardia, normal rhythm and distant heart sounds. This is a serious case as the subject required hospitalisation. He was found to have sinus tachycardia and electrical alternans on electrocardiogram. Chest radiography showed an enlarged cardiac shadow and a chest computed tomography revealed a large pericardial effusion and bilateral pleural effusions. A large pericardial effusion with tamponade physiology was noted on a bedside scan; so the subject underwent pericardiocentesis with catheter placement and pericardial window. Cytology of the fluid obtained in the procedure indicated the presence of an adenocarcinoma and the staining was positive for cytokeratin 7, carcinoembryonic antigen, napsin and thyroid transcription factor 1 which was consistent with lung origin. Subsequent supraclavicular node biopsy confirmed the existence of a metastatic adenocarcinoma of a lung primary tumour. In addition to these tests, he had positron emission tomography-computed tomography and magnetic resonance imaging as an outpatient. The positron emission tomography scan was significant for a fludeoxyglucose avid nodule in the right middle lobe; it was consistent with a primary lung carcinoma with an extensive spread to the abdomen. A brain magnetic resonance imaging showed no evidence of metastatic disease. Treatment apart from the pericardiocentesis with catheter placement and pericardial window was unspecified. The outcome of the events was unspecified at the time of reporting. The authors did not comment on any causal relationship between the vaccine and the events. The authors concluded that "The occurrence of tamponade as the presenting manifestation of an extracardiac malignancy is rare. In subjects presenting with pericardial effusion, pericardiocentesis is vital to provide relief of symptoms and determine the aetiology of the fluid, especially in those with risk factors for malignancy. Cytological examination of the fluid with flow cytometry provides an immediate and accurate means of diagnosis. In general, pericardial effusion in the setting of primary lung cancer tends to be indicative of rapid tumour progression and shorter survival".