ANALYSIS OF FLUID IN CYSTS ACCOMPANYING VARIOUS PRIMARY AND METASTATIC BRAIN-TUMORS - PROTEINS, LACTATE AND PH

There is a growing interest in cystic lesions of the brain. By examini ng the cyst content of brain tumours more insight into the pathogenesi s of cyst formation has been found. In this study, 39 samples of cyst fluid of 34 patients with a cyst accompanying a brain tumour were coll ected and studied biochemically regarding their protein content, lacta te and pH. In this study we investigated the relation between the grad e of malignancy and the lactate-concentration and the discrepancy betw een the high levels of lactate in cysts and their alkaline environment . The results of the measurements of the concentrations of albumin, im munoglobulins (IgG, IgA, IgM) and alpha(2)-macroglobulin in cysts comp ared to those in sera suggest that cyst formation associated with tumo ur is based upon a disruption of the blood-brain barrier with exudatio n of plasma proteins into the brain parenchyma resulting in accumulati on of fluid (oedema) and eventually in formation of a cyst. There appe ars to be a positive relation between the grade of malignancy and the concentration of lactate in the cysts with a significant 2-fold increa se in lactate concentration in malignant tumour cysts compared to the more benign tumour cysts (p < 0.001) probably on account of aerobic gl ycolysis with production of lactate by the tumour. The measured pH val ues in the cysts were above normal, resulting in a discrepancy of the high levels of lactate in the cyst with the alkaline environment and t his suggests efflux of H+-ions by a Na/H exchange mechanism to compens ate for the change of pH.