Hyperechoic Mass

Hemangioma

Hamartoma

Lymphoma and Myeloproliferative Disorders

Table 5.5 lists the differential diagnosis of hyperechoic splenic masses and their incidence.

Benign solid hyperechoic splenic tumor is usually diagnosed as an incidental finding in abdominal ultrasound studies. It is extremely rare, the most common being hemangiomas and hamartomas.

The main advantage of using ultrasound with other tomographic imaging modalities is the ability to differentiate these entities from primarily malignant splenic tumors, splenic metastases, or infiltrates in malignant lymphoma, and from other hyperechoic intrasplenic masses. Only rarely is ultrasound alone able to do that.

Table 5.5 Differential diagnosis of hyperechoic splenic mass

Hemangioma

mon complication, with an incidence of up to 25%.

Ultrasound appearance. Ultrasound can differentiate between two separate types:

●A primarily smooth, homogeneous, hyperechoic and mostly round lesion ( 5.12a–c)

Splenic Calcification

Focal Calcification

Diffuse Calcification

Vascular Calcification

Table 5.6 summarizes the differential diagnosis of splenic calcification.

On ultrasound calcification of the splenic parenchyma presents as solitary or multiple hyperechoic structures, characterized by total or partial posterior shadowing.

Definitive correlation with certain diseases based on the ultrasound findings alone is impossible in most cases. Since they do not require any treatment, the etiology of these mostly incidental findings remains unclear.

Focal calcification will be seen as residual scarring after infarction, hematoma, abscess, or invasive lymphoma, or as part of a metabolic disorder (e. g., chronic renal insufficiency) (Fig. 5.34). Calcification of metastases (e. g., medullary thyroid carcinoma) is rare. Splenic cysts may exhibit intramural calcification. In larger hemangiomas, hemorrhage may lead to calcification as well. Sometimes recurrent splenic infarction will leave substantial splenic scarring. Such a spleen will rarely be visualized as just a calcareous crescent, but this would be characteristic in homozygous sickle-cell anemia. Calcified lymph nodes at the splenic hilum will sometimes be seen as sequelae of tuberculosis.

Diffuse Calcification

Diffusely distributed fine reflectors in the spleen will produce a pattern resembling a “starry sky” (Fig. 5.35). Quite often it is visualized as metainfective scarring and may be associated with calcification of other abdominal organs (e. g., in tuberculosis, systemic histoplasmosis, brucellosis, sarcoidosis, aspergillosis, candidiasis, lupus erythematosus, pneumocystis infection, and also amyloidosis).

Fig. 5.35 Multiple small calcifications in an elderly patient with miliary tuberculosis in her youth.

This should be differentiated from the vascular calcification of the arteries and veins (phleboliths), which is primarily seen at the splenic hilum but also as diffuse calcification within the parenchyma. The etiology remains unclear. It has been reported in a few patients with general vascular sclerosis, renal insufficiency, and long-standing portal hypertension (Fig. 5.36).

Tips, tricks, and pitfalls

In contrast to other organs the size of the spleen can be well estimated and measured. The longitudinal diameter may be sufficient in most cases; the thickness may be added in special cases. Corresponding to the conventional handling, the spleen should be depicted in a scan direction that shows the lower pole on the right image side.

The examination of the spleen is carried out in a supine position, also in a right decubitus position. A deep inspiration is not very helpful because of

Fig. 5.37 CEUS in a patient after blunt abdominal trauma depicts nonenhancing regions corresponding to hematomas or lesions within the spleen.

References

[1]Görg C. Milzdiagnostik mit Ultraschallkontrastmitteln. Konstanz: Schnetztor-Verlag GmbH, 2006

[2]Görg C, Bert T. Contrast enhanced sonography of focal splenic lesions with a second-gener- ation contrast agent. Ultraschall Med 2005;26(6):470–477

the overlapping of the phrenicocostal sinus blocking the sight of the spleen. A high intercostal scan direction is the best access. To inspect the convexity near the thoracic wall it is recommendable to use a 5 MHz transducer.

Cysts in the splenic–renal angle may derive from the spleen, the kidney or as pseudocysts from the pancreatic tail (additional scan from a transverse upper abdominal direction).

Solid masses within the spleen may predominantly signify an organ manifestation of a malig-

Fig. 5.38 In a patient with CLL and left flank pain, CEUS demonstrates a nonenhancing area at the lower pole as a sure sign of a splenic infarction. Some of these infarctions are nonapparent.

[3]Görg C, Schwerk WB. Milzsonographie. In: Braun B, Günther R, Schwerk WB (eds.). Ul- traschalldiagnostik—Lehrbuch und Atlas. Landsberg: ECO med, 2000

[4]Görg C. The forgotten organ: contrast enhanced sonography of the spleen. Eur J Radiol 2007;64(2):189–201

[5]Falk P. Maligne Lymphome in der Milz. Stuttgart: Fischer, 1991

Fig. 5.36 Vascular calcification in chronic renal insufficiency. S = spleen.

nant lymphoma, and require a complete investigation of all abdominal lymph node stations; splenic metastases are rare.

The spleen is involved in the portal circulation; therefore the investigation of the spleen should also include the hepatobiliary system especially in case of an enlarged spleen:

●searching for lymph nodes

●inspection of the portal system and the liver

Special consideration of the spleen is demanded in the early diagnosis of abdominal trauma (Fig. 5.37). An enlarged organ should be followed up by monitoring after 6, 12 and 18 h; so should free fluid detected within the abdomen.

Current studies show that liquid hematomas and small intraparenchymal hemorrhages, not detectable in other imaging procedures, are very well seen when contrast agents (CEUS) are used. CEUS may become the most sensitive procedure especially in trauma-related emergency admissions.

In the detection of disturbed circulation of the spleen CEUS is also a most sensitive procedure (Fig. 5.38). Very small infarctions are detectable, which is significant for prognosis and prevention.

[6]Neiman RS, Orazi A. Disorders of the spleen. 2nd ed. Philadelphia: W.B. Saunders, 1999

[7]Görg C, Görg K, Bert T, Barth P. Colour Doppler ultrasound patterns and clinical follow-up of incidentally found hypoechoic, vascular tumours of the spleen: evidence for a benign tumour. Br J Radiol 2006;79:319–325