Background: Solitary fibrous tumors of the pleura are infrequent neoplasms of mesenchymal origin that are thought to arise from the submesothelial connective tissue and usually have a benign behavior. However, a small proportion of these tumors may recur or metastasize after surgical treatment, especially when they are associated with malignant morphological and histopathological features.

Clinical cases: Two female patients of 56 and 50 years of age who underwent surgical treatment for malignant solitary fibrous tumors of the pleura. The first patient was asymptomatic, whereas the second suffered from coughing, dyspnea and weight loss. The first patient underwent a lung wedge resection and en bloc resection of the chest wall along with the tumor. The second patient underwent multiple lung wedge resections. The histopathological examination showed multiple features associated with malignant behavior in these tumors. After 3 years and 1 year from the time of surgery, respectively, there is no evidence of recurrent or metastatic disease.

Conclusions: Features associated with malignant behavior warrant the need for strict and long-term follow-up by means of chest imaging. It is still uncertain how often and how long this follow-up should be performed.