Question category: Haematology
A 35 year old female presents with fatigue, aches and pains, night sweats and pruritus. She also has diarrhoea, shortness of breath and a dry cough. Bloods reveal a markedly elevated eosinophil count, thrombocytopenia and elevated ESR. There is no clear evidence to suggest allergies, asthma or parasitic infection and a bone marrow biopsy does not suggest malignancy. Which of the following is the most likely diagnosis?