brain swelling; cellulitis; swelling in her toes on the left side; diagnosed with myelitic leukemia; This spontaneous case was reported by a consumer and describes the occurrence of MYELOID LEUKAEMIA (diagnosed with myelitic leukemia), BRAIN OEDEMA (brain swelling) and CELLULITIS (cellulitis) in an 83-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 031L20A and 011L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Toe operation (She has 3 wires in her toes on the left side ) and Knee replacement. Concurrent medical conditions included Leukemia.   On 20-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 17-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 30-Mar-2021, the patient experienced MYELOID LEUKAEMIA (diagnosed with myelitic leukemia) (seriousness criterion medically significant). On an unknown date, the patient experienced BRAIN OEDEMA (brain swelling) (seriousness criterion medically significant), CELLULITIS (cellulitis) (seriousness criterion medically significant) and PERIPHERAL SWELLING (swelling in her toes on the left side). The patient was treated with Manual therapy (put on a walker) for Peripheral swelling. At the time of the report, MYELOID LEUKAEMIA (diagnosed with myelitic leukemia), BRAIN OEDEMA (brain swelling), CELLULITIS (cellulitis) and PERIPHERAL SWELLING (swelling in her toes on the left side) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In November 2020, Heart rate: 144 (Inconclusive) 144 for 45 minutes. In November 2020, Platelet count: 234 (Inconclusive) 234. On 30-Mar-2021, Platelet count: abnormal (abnormal) around 630.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   Concomitant product use was not provided by the reporter. Six weeks after her second shot, on 30-Mar-2021, the patient had another test and her platelets were triple the amount, around 630 and she was diagnosed with myelitic leukemia. She tried taking an unspecified drug as treatment but she experienced brain swelling. The second time she attempted taking half the dose and she also experienced brain swelling and her pulse was 144 for 45 minutes. She had 3 wires in her toes on the left side and new knees, normally she had full range of motion but at the time of this report she was put on a walker because of leg swelling and she got cellulitis from the leg swelling. She was going to try an unspecified pill for her leukemia. She had a letter from her hematologist to get the Pfizer shot and they would not give it to her.  company comment: This case concerns an 83-year-old, female patient with previous relevant medical history of leukaemia, who experienced the unexpected events of myeloid leukaemia, brain oedema, cellulitis and peripheral swelling. The events occurred 43 days after the second dose of mRNA-1273. The rechallenge was not applicable since the events happened after the first dose. The medical history of leukaemia remains a confounder. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This case concerns an 83-year-old, female patient with previous relevant medical history of leukaemia, who experienced the unexpected events of myeloid leukaemia, brain oedema, cellulitis and peripheral swelling. The events occurred 43 days after the second dose of mRNA-1273. The rechallenge was not applicable since the events happened after the first dose. The medical history of leukaemia remains a confounder. The benefit-risk relationship of mRNA-1273 is not affected by this report.