Malignant Mesothelioma of the Pleura with Pleomorphic Features: A Series of 44 Cases
F Galateau-Salle, N Le Stang, P Astoul, P Brochard, JC Pairon, A Gilg Soit Ilg, E Imbernon, M Goldberg. CHU, Caen, France; InVS, Saint Maurice, France
Background: Malignant mesothelioma [MM] is an heterogeneous cancer showing low grade cytologic atypia to extreme pleomorphism with bizarre cells that should not be dismissed as large cell carcinoma or metastatic sarcoma. We present a study of 44 MM with pleomorphic features, the largest series to date.
Design: All cases were retrieved from the MESONAT registry from 1998 to 2006. Clinical histories, radiological reports, follow up and demographic data were recorded using a structured questionnaire. All lesions were reviewed by the MESOPATH panel according to their standardized procedure of certification. Cases fulfilling the following criteria were included: diffuse proliferation of large bizarre/giant cells with pleomorphic nuclei, a sarcomatoid component of less than 10%. The immunohistochemical profile was a broad spectrum cytokeratins positivity, calretinin+ve/WT1+ve/CK5/6 +ve with a cut off >20% and negativity of p63, BerEP4, TTF-1, CEA, CD34, CD68, CD45. Statistical analysis were performed using Kaplan Meyer and cox model and survival was compared to a series of 1521 of non pleomorphic MM.
Results: There were 44 patients with an average age of 69 years old (range 50 to 69 years), with a M/F ratio 4.5/1, respectively 82% (n=36) for male and 18% (n=8) for female. A history of asbestos exposure was observed in 66 % of patients. Clinical data showed pain (42%), fatigue (54%), loss of weight (15%), dyspnea (27%). The initial presentation was: unilateral pleural effusion in 77% of cases, a diffuse pleural thickening in 54%, and a localized pleural based mass in 16%. Hyalin fibrous plaques were present in 4% of cases. The median survival of MM with pleomorphic features was 7 months with a survival at 2 years of 8% [0%;16%] compared respectively to 13 months and 18% for epithelioid type and 5 months with 9% survival at 2 years for sarcomatoid type. There was a significant difference at risk between MM with pleomorphic features compared to conventional epithelioid type (p= 0.001) and sarcomatoid type (p=0.097).
Conclusions: The findings suggest that MM with pleomorphic features is a distinct morphological variant of epithelioid (p=0.001) and sarcomatoid (p=0.097) MM.
Monday, March 22, 2010 2:00 PM
Platform Session: Section E, Monday Afternoon