We present a case of a 58 years old man with a large heterogeneous and well circumscribed soft tissue mass arising from the right pleural surface, found at a computer tomography of his chest. This mass after complete resection through a right lateral open thoracotomy, proved to be a Solitary Fibrous Tumor, previously known as 'benign mesothelioma'. This tumor is usually discovered at routine chest X-rays since patients are either asymptomatic or report atypical symptoms. Only 10-20% of the published cases report a malignant solitary fibrous tumor, however, definite diagnosis can only be made after complete resection which is the proposed diagnostic algorithm for these cases.