I. Metastatic tumor of spleen
1.CT and MRI manifestations
The CT scan of metastatic tumor of spleen shows normal size or mild to moderate enlargement of the spleen, low-density, clear or unclear contour occupying lesions in the spleen, which vary in size and number, with an average CT value of 25Hu in plain scan, or cystic changes. The rate is higher than that of intravenous direct enhancement, which can detect lesions of 5-10 mm in diameter. Most patients with metastatic spleen tumors are accompanied by liver metastases, so liver changes should be paid attention to during the examination.
Splenic metastatic tumors show irregular low signal areas on T1-weighted images, which can be single and multiple with clear margins, and increased signal intensity on T2-weighted images, in which some cases appear central high signal due to increased central necrotic water content. The spleen rarely metastasizes alone, but often involves the liver and lymph nodes at the same time.
2.Imaging methods and comparison
Ultrasound is a simple method, but the machine equipment and the operator’s experience can affect the display of lesions, and generally lesions with a diameter of 10 mm or more can be detected. If there is liquefied necrosis in the lesion, there is increased water and prolonged T2, resulting in high signal on T2-weighted images, which is sometimes difficult to detect on T1-weighted images. The combination of these methods can compensate each other and improve the detection rate.
Primary lymphoma of the spleen
Primary lymphoma of the spleen is generally defined as lymphoma originating in the spleen or splenic hilar lymph nodes. It accounts for only 1% of malignant lymphomas, but still takes the first place among primary malignant tumors of the spleen.
1. Pathologically there are often 4 types.
(1) Uniform diffuse type: uniform enlargement of the spleen without obvious mass formation, diffuse distribution of microscopic tumor cells, diameter
(2) Cornular nodular type: small nodular distribution of lesions with a diameter of 1mm~1mm.
(3) Multiple mass type: multiple lesions, about 1cm～1cm in diameter
(4) Giant mass type: lesions >5cm in diameter.
2.Ultrasound examination
Ultrasound shows the following
(1) Uniform diffuse type: the spleen is uniformly enlarged, the peritoneum is intact and smooth, because it is difficult to show very small nodules, so only slightly low echogenicity is seen in the spleen, and the vessels in the splenic hilum are generally not widened, with this can be distinguished from splenomegaly due to cirrhosis. This type may only suggest PLS when it is accompanied by enlarged lymph nodes in the splenic hilum, combined with other clinical manifestations and ultrasound after examination.
(2) Cornular nodule type: scattered punctate weak echogenicity, which may be lattice-like, honeycomb or sieve-like, with no obvious internal blood flow.
(3) Multiple masses: Unevenly enlarged spleen with several low-echoic homogeneous masses, which may be lobulated, round-like, or irregular in shape, with more regular linear echogenicity at intervals, without obvious envelope and without significant posterior enhancement.
In patients diagnosed with PLS without splenectomy, splenomegaly may be reduced, the mass may become smaller or even disappear, and the residual lesion may have blurred borders and the blood flow signal may be significantly reduced or even difficult to detect after improvement by chemotherapy. The residual lesions may have blurred borders, and the blood flow signal may be significantly reduced or even difficult to detect. The lesions are not filled with contrast after imaging, and they appear anechoic. Long-term follow-up shows the process of lesions gradually becoming smaller and disappearing.
3.CT examination
CT also has several corresponding manifestations.
(1) Homogeneous diffuse type and corn nodule type: both can be shown as splenomegaly with more uniform density, unchanged shape or spherical shape, normal or slightly low CT value, and uneven enhancement after enhancement. However, smaller lesions are often undetectable by CT, and the measurement methods and criteria for spleen size are not yet standardized, so they are more likely to be missed.
(2) Multiple mass type: It is manifested as multiple hypodense foci of different sizes in the spleen, spherical or irregular in shape, with clear or blurred borders, and the enhancement is not obvious after enhancement, and the contrast with normal spleen tissue with obvious enhancement is clearer. If the arterial splenic trabeculae do not appear or the splenic parenchyma shows fine non-nodular enhancement, it is likely to be PLS.
(3) Giant mass type: It appears as a giant left epigastric occupancy, and the normal spleen may disappear completely or only a little remains, which is easily confused with left adrenal gland and left lobe of liver lesions.
4.Magnetic resonance examination
For splenic tumors with unclear boundaries or difficult to identify, oral superparamagnetic contrast can be administered. The lesion usually has a slightly longer T1 and longer T2 signal, and the enhancement is circular or uniform. Gradient-echo fast enhancement scan is valuable for the visualization and diagnosis of the lesion. There are various presentations after enhancement.
(1) diffuse type: it shows irregular high or low signal areas, while the characteristic bowed stripes of normal spleen can be significantly enhanced
(2) Multifocal type: Multiple low-signal foci against high signal, which may be distributed throughout the spleen.
(3) Focal type: T2-weighted low signal, which is a characteristic sign to distinguish lymphoma or metastasis.
Examination of angiosarcoma
Because of early metastasis, intrahepatic metastases or enlarged retroperitoneal lymph nodes are sometimes seen. Ultrasound may reveal a large spleen or even a giant spleen, and single or multiple foci may be seen in the spleen, which may be hyper- or hypoechoic. The nodules may fuse with each other, and the margins are often irregular. In cases with ruptured bleeding, perisplenic fluid can be detected.
Color Doppler can show abundant blood flow in the tumor, mostly arterial blood flow, and CT shows a poorly defined hypointense shadow, solid or containing cystic necrotic areas. The parenchymal area is enhanced to varying degrees after enhancement, which may resemble the enhancement of hemangioma. Magnetic resonance T1-weighted low signal, T2-weighted high signal, signal inhomogeneity, enhancement performance is the same as CT enhancement.