[Clinical and pathological profile of the pleural malignant mesothelioma: A retrospective study about 30 cases]

The malignant pleural mesothelioma (MPM) is a rare tumour usually associated to asbestos exposure. The delay between the exposure and the occurrence of the cancer can reach 40 years. This caused the pick of incidence described in many countries including Tunisia. The diagnosis is suspected based on clinical features but positive diagnosis is microscopic. Our aim was to describe the clinical and microscopic features of MPM through a single institution experience.

We conducted a retrospective study about 30 MPM diagnosed over a 20-year-period (1995-2015). We included only patients with complete records including clinical, radiologic and microscopic features. All the microscopic diagnoses were reviewed by 2 pathologists. A mean of 12 slides per case was reviewed. The diagnosis was based on the 2015 WHO classification.

The mean age of the patients was 61 years, average 22 to 80 years. The sex ratio was 6,5. An asbetose exposition was reported in 21 cases. The most frequent symptoms was chest pain reported in 25 cases. Physical exam was normal in 9 cases. It revealed pleural syndorm in most patients (60 %). Imaging findings consisted mainly in diffuse pleural thickening in 17 cases. Twelve tumours were classified as stage I, 3 stage II, 14 stage III et 1 stage IV. Pleural biopsy was performed using needle in 18 cases, through thoracoscopy in 16 cases, thoracotomy in 3 cases and allowed the diagnosis in respectively 7 cases/18, 16 cases/16 and 3 cases/3. A lymph node biopsy was performed through mediastinoscopy in one case and yelded the diagnosis. The diagnosis was performed on surgical specimen in 2 patients: one bullectomy and one right upper lobectomy. The microscopic exam concluded to an EM in 17 cases, sarcomatoid mesothelioma (SM) in 4 cases and biphasic mesothelioma (BM) in 9 cases. Pan-cytokeratin antibody was used in all cases in association with 2 antibodies with positive diagnostic value and 2 antibodies with negative diagnostic value. It was repeated in 15 cases and the most used antibodies were the anti-calretinin and the TTF1. This was due to the lack of fixation in one case and in order to reach a quality criteria in the other cases. Surgical resection was possible in 2 patients. 15 patients were lost of view after a mean follow-up period of 3 months. Thirteen patients died before or during the follow-up.

This work was about a Tunisian experience in the diagnosis and management of MPM. The major limits faced were the incomplete databases, the small number of patients included. Microsocpic positive diagnosis necessitates a degree of expertise and every laboratory has to determine the most valuable antibodies through its experience in order to optimize the diagnosis and to reduce the delay of diagnosis.