Pseudomesotheliomatous carcinoma of the pleura: an autopsy case of metastasis from a G‐CSF‐producing anaplastic carcinoma of the pancreas

Pseudomesotheliomatous carcinoma is a malignant tumor that extends along the pleura mimicking malignant mesothelioma. An 81‐year‐old male patient presented to our hospital with epigastralgia, and abdominal computed tomography (CT) showed a 36‐mm tumor in the pancreatic tail. The laboratory data revealed a high leukocyte count (>44 000/μL). Chest CT showed left pleural thickening with pleural effusion. The cancer showed a poor response to chemotherapy, and the patient died of respiratory failure at 5 months after the onset of disease. Autopsy showed solid tumor with hemorrhage, measuring 6 cm in diameter, in the pancreatic tail, with wide invasion to the stomach, left adrenal gland, spleen, and diaphragm. The left pleura, which was circumferentially thickened by the involved tumor, macroscopically resembled pleural mesothelioma. Histologically, the primary pancreatic tumor was diagnosed as anaplastic carcinoma, due to the absence of glandular structures or other features that would indicate a definite direction of differentiation. The primary lesion and carcinoma involving the left pleura were all positive for G‐CSF. We recently experienced an autopsy case of G‐CSF‐producing anaplastic carcinoma with pseudomesotheliomatous spread.