Diagnostic Accuracy of Malignant Pleural Effusion Cytology in 2008
F Galateau-Salle, N Le Stang, V Abonnet. CHU Caen, Caen, France
Background: The reported diagnostic accuracy of pleural effusion cytology has varied from 60 to 95% for the diagnosis of metastatic carcinoma [MC] to unsatisfactory (30%) for mesothelioma [MM]. The aim of the study was to evaluate, in 2008 the diagnostic accuracy of conventional pleural effusion cytology [PEC] in our institution, and to assess the usefulness of p16/CDKN2A deletion by FISH as a diagnostic marker for the distinction between benign and malignant mesothelial cells.
Design: A series of 3483 exfoliative PEC and 1659 biopsies were collected from the department of Pathology of CHU Caen during the period 1998-2008. They were systematically analyzed and compared with clinical and or histological follow up. Additionnally a series of 143 patients with a diagnosis of MM and of 347 patients with a diagnosis of MC made either by cytology and /or by a biopsy were selected according to the French system of codification ADICAP code. A dual color FISH for p16/CDKN2A and chromosome 9 centromere was performed either on frozen or paraffin embedded cell blocks from 20 reactive mesothelial hyperplasia [RMH] and 17 positive effusions for MM.
Results: From the 3483 PEC, a diagnosis of malignancy was performed in 12% (n=411), and of benign disease in 88% (n=3072). Among the 411 patients with a positive cytology for malignancy a diagnosis of MM was observed in 9% of cases, of MC in 84% and of lymphoma in 7%. From the series of 143 patients with a positive PEC for MM, the diagnosis was made by thoracoscopy/surgical biopsy in 50% (n=71), by cytology alone in 3% (n=5) and by both in 47% (n=67). From the series of 347 patients with a diagnosis of MC, the diagnosis was made respectively by thoracoscopy/surgical biopsy in 38% (n=133), by cytology alone in 17%(n=58), by both in 45% (n=155). The sensitivity of cytological diagnosis was respectively 36% with a predictive positive value [PPV] of 88% for MM and 52% with a PPV of 90 % for MC. When we compare the period of time from 1998 -2003 to the period from June 2003-2008, the sensitivity and PPV were respectively 19% with a PPV of 83% and 47% with a PPV of 90% for the diagnosis of MM (p<0.05) and of 45% with a PPV of 91% and 57% with a PPV of 90% for MC (p=0.17). Homozygous CDKN2A deletion was detected by FISH in 7 /17 MM cases and in none of RMH (0/20).
Conclusions: Our results show that the diagnostic accuracy of PEC is improving due to a better definition of criteria, and to the use of immunohistochemistry. The detection of homozygous deletion CDKN2A by FISH could be extremely useful for the diagnosis of MM over RMH.
Tuesday, March 10, 2009 11:00 AM
Platform Session: Section F 2, Tuesday Morning