Pulmonary epithelioid haemangioendothelioma (PEH) is a rare lung tumour of vascular origin and low-grade malignancy that affects various organs: liver, central nervous system, lung, etc. A rare malignant case of PEH is described. The cryptic clinical appearance and the nonspecific results of radiography and haematological tests caused great difficulty in arriving at a definite diagnosis. Histological analysis and immunohistochemical detection of CD31+ (a membrane receptor and a sensitive and specific marker for vascular lesions), on open lung biopsy, enabled the correct diagnosis to be made.