You are a PA in haematology, and you have been asked to interpret the following blood results of a 23-year-old female: Hb 103, PLT 42 x 10 9/l, neutrophil count 1.0 x 10 9/l. She has presented to A&E with a sudden onset of dyspnoea, headache fatigue, gingival bleeding and a petechial rash. What is the most likely diagnosis based on the symptoms and blood results?