Introduction:
Non-specific pleuritis (NSP) is a fibrinous or inflammatory pleurisy that is not attributable to a benign or malign etiology. The long-term follow-up results of patients diagnosed with NSP following video-assisted thoracoscopic surgery (VATS) were investigated in this study.

Material and methods:
This investigation focused on 593 patients with exu­dative pleural effusion who underwent VATS between 2011 and 2014. Of the 137 patients diagnosed with NSP, a total of 39 patients were excluded from the study.

Results:
Out of the 98 patients, 78 were male (80%) with their mean age being 52.2 ±15.9 years. The mean follow-up period was 1919 ±744 days. Of these patients, 70 (71.4%) had no specific diagnosis, while 28 patients (28.6%) did have specific diagnoses. Malignancy was detected in seven (7.1%) of those with specific diagnoses, with most of the diagnoses of malignancy detected within the first 36 months. Malignant diseases included mesothelioma (n = 2), lung cancer (n = 2), chronic lymphocytic leukemia (n = 1), soft tissue sarcoma (n = 1), and multiple myeloma (n = 1). Chest radiographs of malignant patients showed that statistically significantly larger amounts of fluid (40% vs. 6.9%, p = 0.026), pleural plaque (20% vs. 1.1%, p = 0.020) and nodules (20% vs. 7.7%, p = 0.020) were detected compared to patients with a benign course.

Conclusions:
Most patients diagnosed with NSP after VATS had a benign disease course. There was a probability of malignancy, although it was low. Meso­thelioma and other malignancies could be seen within the first 36 months after the biopsy. Apart from mesothelioma, other malignancies should also be considered, and further follow-up recommended for patients with a large amount of fluid, plaque and nodules found in the initial VATS images.