Clinical diagnosis
Case 199
【Progress】
Both patients were explained that they did not have a space occupying lesion in the liver.
【Discussion】
There are several systemic veins which possibly drain into liver directly: cholecystic vein, right gastric vein, left gastric vein and paraumbilical veins (1-7). Paraumbilical veins are categorized into superior Sappey vein and inferior Sappey vein (3). Superior Sappey vein comes from superior epigastric vein which collect venous blood from upper abdomen and thorax. Superior epigastric vein branches to superior Sappey vein and intrathoracic vein. Meanwhile, inferior Sappey vein comes from inferior epigastric vein which collect blood from lower abdomen. Inferior epigastric vein flows toward external iliac vein and inferior Sappey vein.
Cholecystic vein drains into liver parenchyma surrounding gall bladder. Right gastric vein drains into dorsal area in the medial segment (S4). Left gastric vein drains into lower area in the lateral segment. Inferior Sappey vein drains into inferior ventral areas in medial and/or lateral segment. Superior Sappey vein drains into upper ventral area in medial segment (1, 2, 6).
Blood properties in portal vein and systemic vein differs. Portal vein contains higher concentration of glucose, fatty acid amino acids than systemic vein. Therefore, the irrigation hepatic areas for these systemic veins can cause the different density compared to those from portal vein due to lipid accumulation. When fatty liver appears, the area from systemic vein spares fatty liver. In the case of non-fatty liver, the area from systemic vein can be fatty probably because of high insulin concentration.
Insulin transport glucose to the liver. Insulin plays a role in the liver to make glycogen and fatty acids from glucose. Further, insulin does a role to inhibit breakdown of triglycerides (fat itself) into fatty acids in adipose tissue (8). Excessive fatty acid converts to phospholipid and cholesterol. Then, the long term lack of insulin induces excessive fatty acids, phospholipid and cholesterol, leading to arterial atherosclerosis. Then, blood with higher concentration of insulin in the right or left gastric vein induces local fatty liver corresponded to the irrigation area of those veins.
Dynamic enhanced CT with contrast medium (6, 7) and dynamic EOB-enhanced MRI or non-enhanced MRI (2) are useful for imaging diagnosis of hepatic pseudo-lesion. Subtle fat deposit between liver parenchyma and the lesion can be compared on T1WI out of phase and hemodynamics of the lesion can be detected on Dynamic MRI. Further, Diffusion WI and ADC values are useful to differentiate the pseudo-lesion from real tumors (Case 1, Figs. 1, 2). Enhanced CT with contrast medium can not only detect dynamic pattern of contrast medium but also investigate the draining vein directly. Actually in Case 2, inferior Sappey veins are demonstrated directly adjacent to the pseudo-lesion on enhanced CT with contrast medium (Figs 3-5).
【Summary】
We present two cases with hepatic pseudo-lesions. A fifty two-year-old male had a pseudo-lesion in a quadrate lobe on EOB-enhanced MRI which demonstrated an inflow of aberrant right gastric vein into the pseudo-lesion. A forty three-year-old female had pseudo-lesions in the medial and lateral segments on enhanced CT with contrast medium which demonstrated inflow veins of inferior Sappey veins into the pseudo-lesions. It is borne in mind that pseudo-lesions in the liver are formed by cholecystic vein, left gastric vein, right gastric vein and paraumbilical veins: inferior Sappey vein and superior Sappey vein. Superior Sappey vein comes from superior epigastric vein and inferior Sappey vein comes from inferior epigastric vein. Insulin plays a role of fat accumulation in the liver and adipose tissue. Then, in case of insulin deficiency, excessive fat acids converted into phospholipid and cholesterol, inducing atherosclerosis. It indicates that when bloop property of systemic vein includes insulin, pseudo-lesion of its irrigation area can create local fatty liver.
【References】
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2020.7.29