Splenic metastases

Splenic metastases are relatively rare on imaging and are more commonly encountered at autopsy. Typically they are part of a widespread metastatic disease.

Epidemiology

The rate of splenic metastases varies between 1-10% of autopsy studies, depending on whether microscopic or macroscopic metastases were included ¹.

Pathology

Most commonly metastases are a solitary splenic (solid or cystic) mass, may rarely be infiltrative ^1,4. Primary sources include ^1,2,5:

• cutaneous malignant melanoma (most common)

• breast cancer

• ovarian cancer

• colorectal cancer

• endometrial carcinoma

• gastric cancer

• lung cancer

• clear cell renal carcinoma ⁶

• pancreatic neuroendocrine tumor ⁷

• thymic carcinoma ⁸

• prostatic adenocarcinoma ⁹

• esophageal cancer ¹⁰

Radiographic features

Ultrasound

• solitary or multiple well-defined masses

• most commonly appear as a hypoechoic lesion (target appearance), although can be iso- or hyperechoic ^3,5

• contrast-enhanced US (CEUS): rapid wash-in and wash-out ⁵

CT

• usually hypoattenuating masses

• cystic components may be present ⁵

MRI

• T1: low signal intensity

• T2: high signal intensity

• C+ (Gd): variable, mostly depending on the primary malignancy ⁵