Localized Malignant Pleural Mesothelioma

CASE REPORTS Case 1 In 1998, a 68-year-old man, smoker, asbestos exposed, who had been diagnosed with bilateral localized pleural epithelial mesothelioma, was treated with six cycles of chemotherapy (cisplatin and doxorubicin) with radiologic complete response, maintained until 2005. In 2005, a computed tomography (CT) scan evidenced a right pleural mass with erosion of the third and fourth ribs, histologically diagnosed as recurrence of pleural mesothelioma and confirmed as localized by fluorodeoxyglucose (FDG)-positron emission tomography (PET). Considering the previous prolonged response to chemotherapy, the patient was treated with five cycles of the same regimen, obtaining a partial response. Therefore, given the circumscribed recurrence, in May 2006, a complete macroscopic excision of the primary tumor, en bloc with all contiguous involved structures (right third and fourth ribs, intercostals muscles and the adjacent pulmonary lobe) was performed. At final pathology, the tumor (4 3 1 cm) was diagnosed as mixed type mesothelioma with initial bone and pulmonary infiltration. Surgical margins were negative. The spectrum of microscopic findings showed several nodules partially necrotic onto desmoplastic stroma, with a Ki-67 of 70% (Figure 1). Immunohistochemical findings supported the mesothelial features, with positivity for calretinine and negativity for carcinoembryonic antigen and Thyroid Transcription Factor-1. After an uneventful postoperative course, the patient received adjuvant radiotherapy. *Oncologia Medica; †Chirurgia Toracica; ‡Day Hospital Pneumologico; and §Anatomia Patologica, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy. Disclosure: The authors declare no conflicts of interest. Address for correspondence: Dr. Marcello Tiseo, Oncologia Medica, Azienda Ospedaliero-Universitaria di Parma, Via Gramsci 14, 43100 Parma, Italy. E-mail: mtiseo@ao.pr.it Copyright © 2009 by the International Association for the Study of Lung Cancer ISSN: 1556-0864/09/0408-1038 1038 Journal of Thoracic Oncology • Volume 4, Number 8, August 2009 Two years later, a local disease recurrence was detected close to the site of previous surgery (Figure 2). The patient was submitted to a further operation. The tumor was resected en bloc with the second rib, the intercostal muscles and part of the first rib; apical parietal pleurectomy was also performed. At histology, the tumor showed the same characteristics and immunohistochemical pattern than the previous one, with a Ki-67 of 30%. At present, the patient is alive and free of disease from 11 months. Case 2 In March 2007, a 64-year-old man, former smoker, with known asbestos exposure, was studied by a thoracic CT scan because of an accidental blunt chest trauma. A lobulated pleural mass (5 5 6 cm) localized in the apex of the left pleural cavity with regular margins and without ribs infiltration was observed (Figure 3). The mass presented an intense uptake at FDG-PET. A CT-guided needle biopsy revealed an inflammatory pseudotumor. Therefore, in May 2007, the patient underwent a complete tumor resection through left postlateral thoracotomy. Macroscopically, the resected tumor appeared as an encapsulated mass of 9 7 6 cm with hemorragic areas. It was diagnosed as sarcomatoid malignant mesothelioma, lymphohistiocitoid variant. At histologic analysis, the neoplastic lesion showed a solid structure, inflammatory infiltration, focal necrosis, intermediate-large fusated cells with abundant cytoplasm, and severe cytologic atypia with frequent atypical mitoses (Figure 4). At immunohistochemistry, cancer cells were diffusely and intensely positive for calretinine and focally for cytokeratins and HBME1; no cell immunoreactivity was demonstrated for S-100, CD34, ALK1, p63, CD3, CD5, CD20, CD68, BCL2, desmine, and actine. After surgery, the patient was submitted to adjuvant radiotherapy and, at the moment, is alive and free of disease from 22 months