Localized fibrous tumors of the pleura are known by various names, including pleural fibroma, fibrous mesothelioma, and localized pleural mesothelioma. These tumors arise from mesenchymal cells rather than epithelial cells and range from benign to malignant.

Typically, patients range in age from 45-65 years of age and there is no association with asbestos exposure. Histologically the tumor is composed of spindle shaped cells interspersed within a collagen matrix. Grossly the lesions appear as pleural based masses. Occasionally they may be surrounded entirely by lung. Seventy five percent arise from the visceral pleura while the remaining twenty five percent arise from the parietal pleura. The mass is pedunclated in fifty percent of the tumors; this form has the greatest association with benignity. Histologically malignant tumors often invade the chest wall and mediastinum.

Clinically the patients are usually asymptomatic and the tumors are found as an incidental finding. The tumors are slow growing and, when symptomatic, the patient presents with cough, pleuritic chest pain, and dyspnea. Hypertrophic osteoarthropathy is seen in 4%-12% of the cases and is more common in larger tumors (> 7cm). Episodic hypoglycemia is reported in up to 6% of patients.

Chest radiographs demonstrate an ovoid homogenous mass in contact with the pleural surface which may invaginate or arise from a fissure. Tumors range is size from 1 to 30 cm. The pleural origin of the mass may be difficult to determine in extremely large masses. The angle of the mass with the chest wall may be obtuse or acute, and peduculated lesions may change position within the chest on subsequent images (and with stages of respiration). Malignant tumors can invade the chest wall and cause destruction of bone.

CT images usually will show well marginated pleural based lesions growing outward from a narrow base forming acute angles with the chest wall (75% of cases). Small tumors show soft tissue attenuation and larger lesions may demonstrate central necrosis. The mass shows homogenous enhancement. Again, lesions may appear to arise from fissures and pedunculated lesions may appear mobile. Pleural effusions are rare and calcification has been reported to occur in 10% of cases.