Electrophoretic patterns of lactate dehydrogenase isoenzymes in fluid from 261 benign breast cysts

BACKGROUND: Some groups have described the presence of lactate dehydrogenase (LDH) and certain isoenzymes in breast cyst fluids, but their clinical usefulness is unknown. We have studied the behavior of LDH isoenzymes in benign breast cysts fluids with the aim of understand their clinical meaning. SUBJECTS AND METHOD: The study group included 261 benign breast cyst fluids classified, according to the Na+ / K+ ratio, as follows: type I (Na+ / K+ >/= 3): 188, and type II (Na+ / K+ > 3):73. The electrophoretic LDG isoenzymes analysis was carried out with the PARAGON system and the Appaise Junior densitometer from Beckman Instruments (U.S.A.). RESULTS: The results were as follows: a) type II was more frequently associated with the presence of LDH than type I breast cyst fluids (41/73 vs 9/188; p < 0.0001) and b) the LDH5 isoenzyme positivity was higher in type II than in type I breast cysts fluids (29/41 vs 4/188; p < 0.001) also and it correlated with higher pH, C1, carcinoembryonic antigen and Na+ / K+ ratio values. CONCLUSIONS: Our results led us to consider that LDH and LDH5 isoenzyme positivity is associated with type II breast cyst fluids, suggesting that it does not reflect a higher transformation risk, but rather that is a consequence of cyst evolution and of its lining wall.