Lipoprotein Analysis in a Chyliform Pleural Effusion: Implications for Pathogenesis and Diagnosis

Abstract

A chyliform effusion is an uncommon high lipid pleural effusion that does not result from a leakage of the thoracic duct. Characteristically, it emerges from chronic pleurisy and contains high levels of cholesterol. The origin of this cholesterol is unknown, but it is often attributed to the degeneration of red and white blood cells. In this study we have carried out detailed lipoprotein analyses in a chyliform effusion, a chronic tuberculous effusion and three inflammatory effusions of recent onset, in an attempt to elucidate the process of cholesterol accumulation and possible lipoprotein alterations. Mean cholesterol was 92 mg/dl in the inflammatory exudates and 1,237 mg/dl in the chyliform effusion. In inflammatory effusions of recent onset most cholesterol was bound to low density lipoprotein (LDL) with corresponding apoprotein B levels. The chronic tuberculous exudate showed a shift of cholesterol binding towards high density lipoprotein (HDL). In the chyliform effusion most cholesterol was found in the HDL region. Our results suggest that in acute inflammation, the pleural barrier opens to plasma LDL. We hypothesize that in chronicity this cholesterol becomes trapped in the pleural space and undergoes a change in lipoprotein binding characteristics. In a chyliform effusion, cholesterol further accumulates and builds complexes containing triglycerides and proteins. In clinical routine, total cholesterol values above 200 mg/dl strongly suggest a chyliform effusion. Since triglyceride values may be as high as in chylous effusions ( > 110mg/dl), the diagnostic routine in all suspected high lipid effusions should involve cholesterol and triglyceride measurements

Diffuse Thyroid Enlargement Following Metastasis of Lung Adenocarcinoma

“…Taken together with enriched triglyceride fluid, retrograde lymphatic dissemination and lymphostasis, rather than hematogenous metastasis, may contribute to goiter formation (8). Moreover, the level of total cholesterol in the patient's fluid was significantly elevated, with a ratio of triglycerides to cholesterol of <1.0, suggesting chyliform effusion (14). Although the serum lipid profile was not available in the current case, the significantly high level of cholesterol in the fluid, in addition to the absence of xanthoma and the patient's past history, excluded the possibility of severe hypercholesterolemia, possibly due to the local collection of cholesterol in the thyroid.…”

Chylothorax or leakage of total parenteral nutrition?

“…The diagnosis is based on the lipid composition of the fluid (high triglycerides and the presence of chylomicrons with low cholesterol). In addition, the lipid profile differentiates chylothorax from pseudochylothorax, which is a fluid with a chyle-like appearance but has no connection with lymphatic vessels or chyle, which contains very high concentrations of cholesterol and no triglycerides or chylomicrons and can develop when fluid is present for a long time in the pleural space and in a fibrotic pleura [1][2][3]. However, in exceptional cases, as the one described here, these diagnostic guidelines may incorrectly suggest chylothorax.…”

“…According to the literature, the pleural fluid fulfilled the criteria for chylothorax, with high triglyceride and low cholesterol concentrations and the presence of chylomicrons (table 1) [1][2][3].…”

“…Because of its structure, the integrity of the thoracic duct can readily be disturbed by relatively weak forces from iatrogenic or noniatrogenic trauma, diseases (malignancies, congestive heart failure, liver cirrhosis), or spontaneously. The diagnosis of chylothorax is based on the lipid profile of pleural fluid: a high triglyceride concentration in the presence of chylomicrons together with a low cholesterol concentration [1][2][3].…”

Chylothorax and pseudochylothorax

“…Triglycerides below 50 mg·dL -1 virtually exclude the diagnosis of chylothorax. Cholesterol values should be measured simultaneously, since high triglyceride levels can occur in pseudochylothorax [2], but the cholesterol level is always very high (>200 mg·dL -1 ), and at microscopy, cholesterol crystals can be seen, which are thought to be diagnostic.…”