3.  Which histologic type of malignant mesothelioma is shown in this photomicrograph?

  4.  Which histologic type of malignant mesothelioma is shown in this photomicrograph?

  5.  A 65-year-old man presents with persistent chest pain and unexplained weight loss. On initial examination, he is found to have a hemorrhagic pleural effusion, which is evacuated. A CT scan reveals irregular pleural thickening. A biopsy of the pleural lesions demonstrates the histopathologic features shown in this photomicrograph. The tumor has diffuse expression of pan-cytokeratin. Which of the following markers, if positive, would support a diagnosis of mesothelioma and rule out adenocarcinoma?

  6.  A pleural tumor composed of tubular and papillary structures raises the differential diagnosis between epithelioid mesothelioma and adenocarcinoma. Which of the following immunostains would be positive if the tumor were a mesothelioma?