Initial unsolicited report received from the literature on 31 March 2017. This case involves a 25-year-old male patient who was vaccinated with a dose of INFLUENZA VACCINE and was also received a dose ACETAMINOPHEN WITH CODEINE, HYDROCORTISONE, a dose of DOBUTAMINE, a dose of NOREPINEPHRINE and a dose of EPINEPHRINE (batch number, expiration date, dose , site and route of administration was not reported) on an unknown date. Patient had medical history of intermittent headache and multiple ER visits for weakness, vomiting, diarrhea and a syncopal episodes was found to have massive hepatosplenomegaly and eosinophilia. Concomitant medications included Dalteparin subcutaneously for DVT prophylaxis. On an unknown date, following the vaccination, the patient developed temperature 102 degree Fahrenheit with stable hemodynamics. On an unknown date, evening of his second hospital day he acutely developed respiratory distress, hypotension and tachycardia 130/min with skin flushing. On an unknown date patient developed severely depressed left ventricle (echocardiogram showed). On an unknown date following the vaccination, within 5 hours of admission to the Medical Intensive Care Unit (MICU) patient developed refractory shock and asystole. On an unknown date following the vaccination, patient developed a rapidly progressive course of shock with multisystem organ failure, pulmonary leukostasis-associated right ventricular failure, severe anaphylactoid reaction, multiorgan failure and overwhelming anaphylactic shock. On an unknown date patient was hospitalized. Patient was intubated and transferred to the Medical Intensive Care Unit. It was reported that drop in hemoglobin was related to fluid resuscitation. On an unknown date patient died. It was also a case of Drug ineffective as hydrocortisone. Relevant laboratory test results included WBC (white blood cell count) 13,500 cells/?L with 72 percentage neutrophils, 5 percentage bands, 5 percentage lymphocytes, 11.7 percentage eosinophils, hemoglobin was 8.5 g/dL, Mean corpuscular volume (MCV) 86.3, platelet count: 110,000/?L. Venous lactate was 0.9 mmol/L. Ferritin was 391 ng/ml. Reticulocyte count, LDH (Lactate dehydrogenase), thyroid stimulating hormone (TSH), ANA (Anti Nuclear Antibodies) and RF (rheumatoid factor) were normal. Chest x-ray showed no abnormalities. Abdomen was benign with marked hepatosplenomegaly. Blood cultures were negative. On an unknown date Repeat CBC (complete blood count) showed hemoglobin 5.9g/dl, and white blood cell count 42,000/mcl with 30percentage degranulating mast cells. Patient received corrective treatment with adequate fluid resuscitation, hydrocortisone, broad-spectrum antibiotics, dobutamine, norepinephrine, epinephrine and vasopressin infusion. Outcome of temperature 102 Fahrenheit was not recovered and was fatal for other event. On an unspecified date autopsy was performed with following details: the bone marrow, spleen and liver were diffusely infiltrated by sheets of hypogranular, atypical, CD117+mast cells with large or double nuclei, open chromatin, and irregular nuclear membranes. These filled the pulmonary and coronary vessels and infiltrated cardiac and pulmonary parenchyma. Documents held by sender: none. Sender's Comments: Reported symptoms and time to onset are consistent with the diagnosis of anaphylactic reaction. Time to onset is compatible with INFLUENZA VACCINE of unknown manufacturer, but additional information including but not limited to the patient's immunization history (i.e., previous immunizations and any adverse events following immunization), allergic history, detail autopsy report and allergy testing to identify the culprit allergen are needed to further assess this case. In this case patient has history of mast cell leukemia with on and off symptoms, as mast cell leukemia can cause sudden release of histamine which could present with above reaction and also in autopsy it has been mentioned that there is infiltration of mast cells in bone marrow, liver and spleen. Based on available information the role of vaccine is unlikely. And also there is lack of efficacy for HYDROCORTISONE, DOBUTAMINE, NOREPINEPHRINE and EPINEPHRINE as patient experienced asystole and refractory shock even after administration of these drugs. Reported Cause(s) of Death: Severe anaphylactoid reaction; Autopsy-determined Cause(s) of Death: Severe anaphylactoid reaction.