Splenic cysts

Simple and parasitic cysts

True cysts and pseudocysts of the spleen are indistinguishable from each other using diagnostic imaging methods. On ultrasound, they appear as classic unilocular anechoic structures with clear margins. On CT, these are water-density lesions without a visible wall that do not enhance with contrast media.

On MRI, simple cysts show low signal on T1-weighted images (T1WI) and high signal on T2WI. The exception is cysts filled with proteinaceous fluid (proteinaceous fluid) — they may demonstrate high signal intensity on T1WI.

Parasitic cysts (most commonly caused by Echinococcus) have several specific features. In addition to a rounded shape and fluid density, they are characterized by ring-like calcification and the presence of small daughter cysts at the periphery. Due to hydatid sand (hydatid sand) and internal debris, the structure of a parasitic cyst may be heterogeneous.

Benign tumors: hemangiomas, lymphangiomas, and hamartomas

Benign vascular tumors may have a cystic structure and require careful differential diagnosis.

• Hemangiomas (Haemangioma). These are usually asymptomatic solitary lesions (multiple lesions occur in Klippel-Trenaunay-Weber syndrome). They can be solid, mixed, or entirely cystic. Ultrasound reveals small cystic areas, echogenic calcifications with acoustic shadowing, and blood flow in solid zones. The main diagnostic sign on MRI and CT is progressive contrast enhancement from the arterial to the portovenous phase with complete filling in the equilibrium phase (similar to the blood pool). On STIR MRI sequences, hemangiomas are markedly hyperintense.
• Lymphangiomas (Lymphangiomas). These are endothelium-lined cavities filled with proteinaceous fluid. The lesions increase the volume of the spleen, presenting a multilocular structure with septations (septations). On unenhanced CT, marginal linear calcifications can be seen, and in the portal venous phase of contrast enhancement, enhancement of the septa themselves is clearly visible.
• Hamartomas. Solitary lesions that can be either cystic or solid. Solid variants blend with the normal splenic parenchyma on imaging characteristics.

Malignant lesions with a cystic component

Primary tumors, lymphomas, and metastases can mimic cystic changes in the parenchyma.

Angiosarcoma (Angiosarcoma) is a rare primary tumor with a poor prognosis. It manifests as multiple nodes or solitary complex lesions. It is characterized by areas of hemorrhage (appearing as high-density zones on CT or hypointense rims on MRI). Contrast enhancement is heterogeneous in the arterial and portal phases, leveling off in the delayed phase.

Lymphoma (Lymphoma) is not always accompanied by splenomegaly, and conversely, organ enlargement does not guarantee the presence of lymphoma. Cyst-like large lesions in lymphoma are markedly hypoechoic on ultrasound, but unlike true cysts, they lack posterior acoustic enhancement. On CT, the most reliable sign is a combination of splenomegaly, focal contrast enhancement defects, and splenic hilum adenopathy.

Metastases (Metastases) to the spleen are rare (half of the cases are melanoma, the rest are adenocarcinomas). They can present as ill-defined lesions or as well-circumscribed single- and multilocular water-density structures.

Important nuance: a cystic metastasis on CT can be completely indistinguishable from a simple benign cyst. On MRI, melanoma metastases or hemorrhagic foci show a specific high signal on T1WI. Contrast enhancement occurs along the septa and periphery.

Class and exam questions

What else to study on this topic

• Parasitic splenic lesions: life cycle of Echinococcus and WHO classification stages
• Klippel-Trenaunay-Weber syndrome and generalized angiomatosis
• Differential diagnosis of splenomegaly in leukemias and portal hypertension
• FDG-PET/CT in assessing malignancy of splenic lesions

Other topics in the section "Diagnostic Radiology of the Abdominal Organs"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.