A 29-year-old man presented with sudden left-sided pleuritic chest pain on a 
background of sore throat during the preceding week. On examination he had 
tender cervical lymphadenopathy, he was tachycardic and had a 24 mm Hg blood 
pressure difference between the left and right arms. Bloods revealed deranged 
liver function tests and a lymphocytosis. His D-dimer was raised, hence he was 
treated for presumed pulmonary embolism before imaging was available. Monospot 
test was positive. He subsequently had both a CT pulmonary angiogram and a CT 
angiogram of the aorta to exclude pulmonary embolism and aortic dissection. The 
CT revealed splenomegaly with a large subdiaphragmatic haematoma secondary to 
splenic rupture. This had likely caused referred pain through diaphragmatic 
irritation. He was taken to theatre for urgent splenectomy. The unifying 
diagnosis was infectious mononucleosis complicated by spontaneous splenic 
rupture secondary to Epstein-Barr virus infection.