What are some malignant lesions that may involve the spleen?
Lymphoma, leukemia, metastatic disease, and angiosarcoma.
Lymphoma is the most common splenic malignancy and is most commonly due to secondary involvement by non-Hodgkin’s lymphoma in up to 40% of patients. The most common appearance of lymphoma is splenomegaly. In some patients, one or more focal hypoenhancing splenic lesions are seen, which are typically homogeneous in appearance, have low attenuation and intermediate T1-weighted and low-intermediate T2-weighted signal intensity relative to spleen, and have hypoenhancement, often along with areas of lymphadenopathy.
Leukemia in the spleen also most commonly appears as splenomegaly, sometimes with multiple small hypoenhancing splenic lesions.
Metastatic disease uncommonly affects the spleen in up to 7% of patients with malignancy, most often due to melanoma and breast cancer and less often from cancers of the lung, colon, stomach, ovary, endometrium, and prostate gland. These are often poorly marginated, heterogeneous, and multiple, and have low attenuation and low-intermediate T1-weighted and intermediate-high T2-weighted signal intensity relative to spleen, along with heterogeneous enhancement, usually with peripheral rim enhancement. When present, cystic/necrotic areas have fluid attenuation, low T1-weighted and very high T2-weighted signal intensity, hemorrhagic components have soft tissue attenuation and high T1-weighted signal intensity, and calcifications have very high attenuation and are difficult to visualize on MR images.
Angiosarcoma is the most common primary malignant nonlymphoid tumor of the spleen and is highly aggressive with a poor prognosis, but it is exceedingly rare. Typically, a nodular heterogeneous ill-defined splenic mass with solid enhancing and cystic components is encountered, often in association with splenomegaly and metastatic disease.