Synchronous Pulmonary Carcinoma and Pleural Diffuse Malignant Mesothelioma

Synchronous Pulmonary Carcinoma and Pleural Diffuse Malignant Mesothelioma
Archives of Pathology & Laboratory Medicine, May 2006 by Allen, Timothy Craig, Moran, Cesar

* Synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma is rare. Cases from the archives of 2 large referral centers were reviewed to identify cases of synchronously occurring pulmonary carcinoma and pleural diffuse malignant mesothelioma. Three cases of synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma were identified from more than 16 000 pleuropulmonary cases and were reviewed for demographic, clinical, radiographie, histologie, and immunohistochemical findings. The patients were men who were 63, 67, and 77 years old. Two had positive smoking histories; the smoking history of the other patient is unknown. One patient had a positive history of asbestos exposure; one patient had no history of asbestos exposure; and one patient's history of asbestos exposure is unknown. The patients underwent surgery for treatment of adenocarcinoma that was diagnosed preoperatively. Two of the adenocarcinomas were of a predominantly bronchioloalveolar pattern. No diffuse malignant mesothelioma was identified preoperatively. Diffuse malignant mesothelioma was suspected on the basis of pleural involvement by tumor with histology differing from that of the adenocarcinoma. Tumor immunostaining supported the diagnoses. The average survival after diagnosis was 6 weeks or less. In summary, the paucity of cases at 2 large referral centers and the paucity of cases reported in the English language literature highlights the rarity of synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma. These synchronous neoplasms occur in patients who have risk factors for both neoplasms independently. Length of survival following diagnosis is bleak.
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(Arch Pathol Lab Med. 2006;130:721-724)

The simultaneous occurrence of multiple primary pleuropulmonary malignancies is rare, and although simultaneous primary pleuropulmonary malignancies have been reported in patients with significant occupational exposure to asbestos,1-4 only 14 cases of synchronous pulmonary carcinoma and pleural diffuse malignant mesothelioma have been reported in the English language literature.5-10 Table 1 shows findings regarding the 14 previously reported cases. We present 3 cases identified from the archives of 2 large referral centers, and review these cases to identify any characteristic features or diagnostic problems.

MATERIALS AND METHODS

We reviewed cases from the archives of 2 large referral centers: Baylor College of Medicine for the past 25 years and M. D. Anderson Hospital for the past 10 years. We identified 3 cases (approximately 0.019%) of synchronously occurring pulmonary carcinoma and pleural diffuse malignant mesothelioma from among more than 16000 archived pleuropulmonary cases. One case had been previously reported,7 Criteria for inclusion required the concurrent occurrence of primary pulmonary carcinoma and pleural diffuse malignant mesothelioma. All other metastatic neoplasms to the pleura were excluded. cases were reviewed for demographic, clinical, and radiographic findings as well as histologic and immunohistochemical findings. Tables 2 and 3 show the demographic and immunohistochemical findings, respectively. The criteria used to diagnose primary pulmonary carcinoma and pleural diffuse malignant mesothelioma are those that have been previously published.11,12

PATHOLOGIC FINDINGS

The patients were men aged 63, 67, and 77 years. Patients 1 and 2 had smoking histories; the smoking history of patient 3 is unknown. Patient 1 worked as an insulator and was found to have asbestosis. Patient 2 had no significant history of asbestos exposure. No information is available regarding asbestos exposure for patient 3. For all patients, survival after diagnosis was 6 weeks or less.

Radiographically, diffuse malignant mesothelioma was suspected in these patients on the basis of pleural effusions and pleural involvement by tumor. All 3 patients had pleural effusions and were suspected of having a pleural malignancy. Patients 1 and 3 had preoperative diagnoses of adenocarcinomas with a predominantly bronchioloalveolar pattern. Patient 1 had a right pleural effusion and consolidation of the right lower lobe, and was found to have a 1-cm adenocarcinoma with a predominantly bronchioloalveolar pattern. Patient 2 was found to have advanced-stage lung adenocarcinoma, arising in the right upper lobe and extending into subpleural adipose tissue; he was treated with chemotherapy. Information regarding specific site and size of tumor for patient 3 was not available. No patient had a tissue diagnosis of diffuse malignant mesothelioma prior to surgery; diffuse malignant mesothelioma was found in patient 2 at autopsy.

Patient 1 was found to have epithelial diffuse malignant mesothelioma, measuring approximately 14 cm in greatest dimension, involving the right pleura. Patient 2 was found to have biphasic diffuse malignant mesothelioma involving the left pleura and left upper lobe, with extension into the chest wall. Patient 3 was found to have biphasic diffuse malignant mesothelioma. Information regarding specific site and size of the tumor is not available. Histologically, the epithelial diffuse malignant mesothelioma showed epithelioid cells arranged in sheets and cords, with acinar structures present in some areas. Tumor necrosis was focally present. Desmoplastic reaction surrounded nests of adenocarcinoma in some areas. The 2 biphasic diffuse malignant mesotheliomas contained an epithelial component with features as described, as well as a spindle cell component arranged predominantly in sheets. Some areas of necrosis were present within the sheets of spindle cells (Figures 1 through 4).