■ Nonfocal Changes of the Spleen

Diffuse Parenchymal Changes

Focal Changes of the Spleen

tion of individual focal masses (compared with healthy hepatic parenchyma, the tissue of the healthy spleen appears somewhat “more homogeneous”). However, the transition to focal micronodular splenic disorder is fluent.

Diffuse nonhomogeneity may be demonstrated in some cases of:

●Collagen disease (e. g., rheumatoid arthritis, lupus erythematosus, polyarteritis nodosa)

● Benign granulomatous disease (Fig. 5.12) (e. g., tuberculosis, Wegener granulomatosis, sarcoidosis)

●Bacterial infection

●Amyloidosis (Fig. 5.13)

●Obstruction of the splenic artery

●Thorotrast exposure (Fig 5.14)

●Portal hypertension (Fig. 5.15)

●Incidental finding in “healthy” patients (Fig. 5.16a)

Vascular causes of diffuse nonhomogeneity of the spleen can be reliably detected by CEUS (Fig. 5.16b,c).

Fig. 5.12a and b Diffuse textural nonhomogeneity of the spleen (S) with undulating surface in Wegener disease. This finding is compatible with granulomatous invasion.

Large Spleen

Infection

Congestive Splenomegaly

Systemic Hematological Malignancy

Table 5.1 Possible causes of splenomegaly

Acute and chronic systemic infection

Infectious mononucleosis, chickenpox, hepatitis, AIDS, sepsis, endocarditis, typhus, tuberculosis, malaria, toxoplasmosis, leishmaniasis, candidiasis

Disorders of the portal circulation

Hepatic cirrhosis, thrombosis of the portal and splenic veins, AV fistula of the spleen

Hemolytic disorders

Pernicious anemia, spherocytosis, thalassemia, sickle-cell anemia

Malignant systemic disease

Leukemia, myeloproliferative disorders, myelodysplastic syndrome, non-Hodgkin lymphoma, Hodgkin lymphoma, malignant histiocytosis, systemic mastocytosis

Immune disorders

Collagen disease, idiopathic thrombocytopenic purpura, Evans syndrome

Other

Amyloidosis, Wegener disease, sarcoidosis, hemochromatosis, lipidosis

Differential diagnosis of splenomegaly covers an extremely wide range of possibilities (Table 5.1). Experience tells us that any ultrasound study of the spleen is not by itself sufficient for pinpointing the definite cause of splenomegaly.

Severity. Although the size of the spleen may vary rather widely between patients with the same disease, assessing the dimensions of the organ may yield some differential diagnostic clues.

Mild to moderate splenomegaly is encountered, e. g., in infections and granulomatous disease (Fig. 5.17), portal hypertension (Figs. 5.20, 5.21), and acute leukemia.

Severe splenomegaly is typical of, e. g., malignant lymphoma, hemolytic anemia (Fig. 5.18), storage disease, infectious mononucleosis (Fig. 5.19), and leishmaniasis.

Extreme splenomegaly is seen in myelofibrosis, in terminal chronic myelocytic leukemia (CML; Fig. 5.23), and also in advanced lowgrade malignant lymphomas (Fig. 5.24). In some cases ultrasound may not be able to ascertain the exact size of the spleen.

Fig. 5.17a and b Hepatosplenomegaly in sarcoidosis. Hepatic involvement was confirmed by histology.

Fig. 5.18 A 40-year-old patient with spherocytosis.

a Frequently there are bilirubin gallstones in the gallbladder (GB) due to the chronic hemolysis.

b Splenomegaly. GB = gallbladder; VP = portal vein.

Congestive Splenomegaly

Hepatic cirrhosis and portal hypertension.

Splenomegaly is observed in 50–75% of patients with cirrhosis of the liver and portal hypertension (Fig. 5.20, Fig. 5.21). The causes are:

●Passive congestion (diminished portal venous outflow)

●Hypercirculation (increased splanchnic inflow)

●Intrinsic splenic factors (e. g., autoimmune processes)

This is counteracted by hemodynamically important portosystemic shunts, the extent of which may vary significantly from patient to patient. A regular-sized spleen does not rule out portal hypertension.

Splenic vein thrombosis. In thrombosis of the splenic vein, splenomegaly will be observed in approximately 60% of patients. A regular-sized spleen does not rule out splenic vein thrombosis. Ultrasound will visualize thrombosis of the

splenic vein as a homogeneously echogenic mass of varying severity within the lumen of the vessel (Fig. 5.22). Color-flow Doppler imaging will demonstrate the lack of flow as well as the collateral circulation and thus confirm the preliminary diagnosis.

Fig. 5.20 Cirrhosis of the liver.

a Hepatic cirrhosis (L) and ascites confirmed by histology. b Congestive splenomegaly (S).

Myeloproliferative disorder. Splenomegaly is regarded as the principal diagnostic sign in myeloproliferative disorders, particularly in myelofibrosis and CML (Fig. 5.23). It is found in approximately 70% of CML cases at the time of primary diagnosis, and after several years frequently results in an extremely large spleen. The number of circulating blast cells and the size of the spleen are decisive prognostic parameters.

High-grade lymphoma. In high-grade lymphoma, the size of the spleen is an unreliable

indicator of possible splenic involvement. Despite the fact that increasing splenic size will raise the probability of invasion by the lymphoma, a normal-sized spleen does not rule out possible involvement of the spleen.5

Low-grade lymphoma. In low-grade lymphoma, particularly in chronic lymphocytic leukemia (CLL; Fig. 5.24), hairy cell leukemia, and also immunocytoma, splenomegaly will point toward a highly probable invasion of the spleen, even if the sonographic echo pattern of the organ is homogeneous. This has to

do with the fact that these entities are characterized by a leukemic course. Demonstration of splenomegaly is of prognostic significance, particularly in CLL.

Hodgkin disease. Use of splenic size as the sole criterion for possible involvement of the spleen has been abandoned. Approximately one-third of all affected spleens are normal in size. In contrast to almost all non-Hodgkin lymphomas, in Hodgkin disease the correlation between splenic size and extent of organ involvement is only tenuous.