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INTRODUCTION

Tumors of the pleura are uncommon and, when they arise, almost always malignant. Malignant mesothelioma and malignant pleural metastases are far more common than benign pleural tumors. Primary benign tumors of the pleura constitute only 5% of all pleural tumors and include solitary fibrous tumors, lipomas and lipoblastomas, adenomatoid tumors, and calcifying fibrous tumors. Of these, solitary fibrous tumors are the most common and will be the primary focus of this chapter. There have been fewer than one thousand cases of solitary fibrous tumor reported in the published literature since the entity was first described by Klemperer and Rabin in 1931.1

GENERAL PRINCIPLES

Solitary fibrous tumor has been known for many decades, but its nomenclature has evolved. In the original description in 1931, Klemperer and Rabin classified mesothelioma as either “localized” or “diffuse.”1 Since that time, solitary fibrous tumor has previously been described as “localized mesothelioma,” “benign mesothelioma,” “solitary fibrous mesothelioma,” or “pleural fibroma.” These terms reflected the incorrect assumption that these tumors were related to malignant mesothelioma of the pleura. More recent research has shown that solitary fibrous tumors originate from mesenchymal cells or fibroblasts in the subserosal or submesothelial layer of the pleura, not in the mesothelial layer, which is distinct from mesothelioma (Fig. 131-1).2 Moreover, solitary fibrous tumors are not associated with asbestos exposure, further indicating a unique pathophysiologic process in the origin of these tumors. Solitary fibrous tumors may arise in other areas of the body as well, such as in the head, mediastinum, abdominal cavity, and extremities.

Figure 131-1

Five layers of the pleural membrane: mesothelial layer, submesothelial connective tissue layer, superficial elastic tissue layer, loose subpleural connective tissue layer, and fibroelastic layer.

Solitary fibrous tumors are rare. A contemporary estimate of an age-adjusted incidence indicates a rate of 0.14 per 100,0003 in comparison to mesothelioma, which has an incidence of approximately 2 per 100,000.4 Solitary fibrous tumors occur equally in men and women, and their incidence is highest during the fourth to seventh decades of life. It is asymptomatic in approximately half of cases. In the other half of patients, solitary fibrous tumors can be associated with either intrathoracic or extrathoracic manifestations. Intrathoracic symptoms are related to the mass effect of the tumor itself on the lungs or chest wall, which can result in dyspnea, chest pain, or a chronic cough. Extrathoracic manifestations are paraneoplastic and manifest as hypertrophic pulmonary osteoarthropathy or clubbing of the digits in 20% (Pierre-Marie-Bamberger syndrome), hypoglycemia in 5% (Doege-Potter syndrome), gynecomastia, or galactorrhea. Constitutional symptoms also may be present, such as fever, fatigue, and weight loss.

Solitary fibrous tumors most commonly arise on the visceral side of the pleura and are usually ovoid in shape (Figs. 131-2 and 131-3). As the name ...

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