More than 50 causes of pleural effusion are known and, although the majority are benign (85%), both malignant and unknown causes are common.1,2 
If the cause of pleural effusion is not found after thoracocentesis, a pleural biopsy is indicated. Medical thoracoscopy (MT) is considered the gold-standard for the diagnostic investigation of a pleural effusion with the highest diagnostic yield. Nevertheless, there are some clinical situations where the diagnostic accuracy of a ‘blind biopsy’ is high, like tuberculosis.3-5 
Non-specific-pleuritis (NSP) is an inflammatory pleuritis that cannot be attributed to a specific cause. Malignancy is reportedly found in about 5% to 25% of cases (mostly mesotheliomas).2
We carried out a prospective study which followed patients with NSP after medical thoracoscopy and the aim was to assess the incidence rate of pleural malignancy.

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