Primary and metastatic pleural neoplasms, and non‐neoplastic pleural diseases, can have similar clinical, radiographic, and gross features. However, treatments and prognoses of these diverse pleural conditions vary greatly. Accurate diagnosis of pleural disease is therefore extremely important; and histologic interpretation of pleural biopsies is vital to rendering an accurate diagnosis. Smaller biopsies contribute to the difficulties in accurately characterizing pleural lesions; and immunostains are frequently employed in their assessment.

Diffuse malignant mesothelioma, the most common primary pulmonary neoplasm, is rare; however, other less common primary pleural neoplasms, including solitary fibrous tumor, the most common benign primary pleural neoplasm, occur. These neoplasm...