Diagnostic Ultrasound - Abdomen and Pelvis

Focal Splenic Lesion
Differential Diagnoses: Spleen
DIFFERENTIAL DIAGNOSIS
Common
• Acquired Splenic Cyst
Less Common
• Congenital (Epidermoid) Cyst
• Infected Cyst/Abscess
○ Pyogenic Abscess
○ Fungal Abscess
○ Parasitic Abscess (Hydatid Cyst)
○ Granulomatous Abscess
• Hemangioma
• Malignant Neoplasm
○ Lymphoma
○ Metastasis
• Splenic Infarct
• Splenic Hematoma/Laceration
Rare but Important
• Hamartoma
• Lymphangioma
• Primary Vascular Neoplasm
○ Littoral Cell Angioma
○ Angiosarcoma
• Sarcoidosis
• Peliosis
• Intrasplenic Pseudocyst
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
• Differentiate cystic from solid or vascular lesion
○ Clear fluid content is anechoic
○ Thick fluid content (proteinaceous fluid, hemorrhage,
abscess) shows low-level internal echoes, mimics solid
lesion
– Grayscale movement of internal echoes and fluid level
suggest fluid nature
– Bright band sign of infarct could mimic internal
echoes; assess shape
○ Use color or power Doppler
– Presence of internal vascularity suggests solid nature
rather than thick fluid content
– Absence of color or power Doppler signal suggests
cystic lesion or infarct; however, absent flow does not
always exclude solid nature; may need further
evaluation with contrast enhanced CT or MR
– If anechoic component completely fills with color →
high flow vascular space, e.g., intrasplenic aneurysm or
pseudoaneurysm
○ Some lesions can have mixed cystic and solid
appearance, for example
– Early abscess formation in inflammatory phlegmon
– Hemangioma, lymphangioma
– Malignant tumor (irregular internal necrosis)
• If cystic, distinguish between unilocular and multilocular
○ Unilocular: Acquired or congenital cysts, abscess, cystic
neoplasm
○ Multilocular: Septated or infected cysts, hydatid cysts,
organizing hematoma, hemangioma, lymphangioma
• Determine if abnormality is solitary or multifocal
○ Solitary: Consider acquired or congenital cyst, pyogenic
abscess, hydatid cyst, infarct or hematoma, benign or
malignant tumors
○ Multiple: Consider pyogenic, fungal or granulomatous
abscesses, benign or malignant tumors (particularly
metastases, lymphoma), peliosis, sarcoidosis
• Note: There is considerable overlap in imaging appearance
of focal splenic pathologies
○ Also, specific pathologies may have broad spectrum of
appearances (ranging from hypo- to iso- to hyperechoic
or from cystic to solid to mixed)
○ Often, CT or MR may be needed for further
characterization
Helpful Clues for Common Diagnoses
• Acquired Splenic Cyst
○ Secondary cyst, due to liquefactive necrosis with cystic
degeneration within lesions; 80% of cysts
– Prior trauma (hematoma), infarction, infection,
pancreatitis
– Remote history of left upper quadrant injury can often
be obtained (majority are post-traumatic)
○ Compared to primary (congenital) cysts, acquired cyst
usually smaller, well defined; often anechoic with thicker
fibrous wall; ± calcification, ± debris
Helpful Clues for Less Common Diagnoses
• Congenital (Epidermoid) Cyst
○ True cyst, lined by epithelium; 20% of cysts
○ Compared to secondary (acquired) cyst, epidermoid
typically larger, well defined, anechoic, unilocular thin
wall; ± calcification (uncommon); ± debris
• Infected Cyst/Abscess
○ Pyogenic Abscess
– Solitary or multiple
– Mobile low-level internal echoes to anechoic with
posterior acoustic enhancement
– Irregular wall, no capsule or pseudocapsule, ± internal
gas
– Rim enhancement on CT is less frequently seen than
in hepatic abscesses
○ Fungal Abscess
– Most common in immunocompromised patients, e.g.,
Candida
– Multiple, small (few mm to 2 cm), hypoechoic foci
representing microabscesses
– Typically target appearance: Hypoechoic center =
central necrotic hyphae, hyperechoic ring = concentric
band of viable fungal element, outermost hypoechoic
rim = inflammation
○ Parasitic Abscess (Hydatid Cyst)
– Hydatid cysts rarely involve spleen (less than 2% of
patients with echinococcosis)
– Usually due to systemic dissemination and
intraperitoneal spread from ruptured liver cyst
– Appearances similar to hepatic hydatid cysts; majority
are anechoic with thin wall ± septa, ± calc
○ Granulomatous Abscess
– Due to TB, atypical mycobacterium (MAC);
histoplasmosis; cat scratch disease
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