Non-specific pleuritis in patients with active malignancy

Pleuroscopy is the test of choice for patients with suspected malignant pleural effusion and negative cytology. Biopsies negative for malignancy are frequently attributed to non-specific pleuritis, which poses a dilemma in patients with a known active malignancy, raising concern for a false-negative result. Our primary objective was to determine the outcomes of patients with active malignancy who had a non-malignant diagnosis on pleuroscopy.

Retrospective review of all pleuroscopy cases from January 2005 to January 2015 at our institution was conducted. Biopsies were categorized by histopathology as malignant, eosinophilic or non-specific pleuritis. Malignant histopathology was considered a true positive. Eosinophilic or non-specific pleuritis was categorized as malignant, if malignancy was later identified during follow-up, or chemotherapy induced, possible radiation induced, other paramalignant, other benign or idiopathic.

Of the 199 pleuroscopy cases reviewed, 172 (86%) had a history of active malignancy. On histopathology, 73 (42%) had malignancy, 9 (5%) had eosinophilic pleuritis and 90 (52%) had non-specific pleuritis. Three patients with non-specific pleuritis were diagnosed with malignancy at follow-up. Pleuritis in 24 patients was chemotherapy induced, 27 were possibly radiation induced, 11 were other paramalignant and 3 were other benign. Idiopathic pleuritis was diagnosed in 31 patients. Patients were monitored for a mean of 23 ± 11 months.

The prevalence of malignant pleural disease was lower than expected for our patient population. Patients with no malignancy on histopathology were most likely to have non-specific pleuritis, a cause for which was identified in a majority of patients after clinical review.