Although talc slurry pleurodesis is effective for control of malignant
pleural effusions and recurrent pneumothorax, the mechanisms of pleur
odesis remain incompletely defined. We instilled 70 mg/kg of sterile a
sbestos-free talc slurry into the pleural space of New Zealand white r
abbits and studied the inflammatory response at 1, 2, 3, 7, 15, 30, 60
, 90, and 120 days by observing pleural fluid and histologic character
istics. Talc slurry caused mesothelial denudement and an exudative neu
trophilic pleural effusion that resolved after 48 h. A transient monon
uclear vasculitis was seen within the lung at 1, 2, and 3 days after i
nstillation. Pleural adhesions were minimal and did not increase in nu
mber over time. Talc was found outside of the pleural space in mediast
inal lymph nodes (4 of 23 animals examined), kidney (1 of 6), and sple
en (4 of 10). The predominant cause of pleurodesis with talc slurry in
stillation is an acute pleural injury similar to the tetracycline clas
s agents.