Ultrasonography
The Spleen
VCA 341 Dr. LeeAnn Pack lpack@upei.ca
Spleen
Indications
Splenomegaly Palpable splenic mass Cranial abdominal organomegaly Lethargy, collapse Anemia, abnormal RBC’s
Spleen
Ultrasound Technique
Left side of body Head of spleen
– Under border of rib cage on left
Body & tail of spleen
– Along left body wall – Ventral or lateral to left kidney
Scan sagittal & transverse
Spleen
Anatomy
Size of normal spleen variable
– Assessed subjectively – Enlarged spleen may cross midline or extend caudally to the bladder
Parenchyma
– Homogenous, finely textured
Echogenicity
– Dog: – Cat: Spleen > liver > kidney Spleen = liver > kidney
Spleen
Normal Spleen
Spleen
Anatomy
Capsule
– Smooth, regular, VERY echogenic
Splenic veins
– Only other structure normally visualized – Poorly visualized except near hilus
•“Whale tail”
– Enlargement subjective
Hilus
– Check for lymphadenopathy
Spleen
Splenic Hilus
Spleen
Pathology
Diffuse splenomegaly
– Congestion – Torsion – Inflammation/septicemia – Neoplasia
•Lymphosarcoma •Mast cell tumor
– Phenothiazine tranquilizers & barbiturate anaesthetics – Extramedullary hematopoesis
Spleen
Pathology
Focal or multifocal splenic lesions
– Hematoma – Infarcts – Cysts – Abscess – Nodular hyperplasia – Neoplasia
•Hemangioma •Hemangiosarcoma
Spleen
Diffuse Splenomegaly
Diffuse increase in echogenicity uncommon
– Neoplastic (mast cell or lymphosarcoma)
Diffuse decrease in echogenicity more common
– Congestion – Extra-medullary hematopoesis – Lymphosarcoma – Inflammation/ septicemia – Torsion
Normal echogenicity can occur with lymphosarcoma & mast cell tumor
Spleen
Non Homogenous
Spleen
Focal/Multifocal Lesions
More common than diffuse Anechoic
– Cysts
•Hematoma/neoplasia
Hypoechoic
– Neoplasia – Abscess – Acute infarct – Nodular hyperplasia
Spleen
Focal/Multifocal Lesions
Hyperechoic
– Neoplasia – Abscess – Chronic infarct – Nodular hyperplasia
Mixed echogenicity
– Neoplasia – Hematoma – Abscess – Nodular hyperplasia
Spleen
Splenic Mass
Spleen
Splenic Mass
Spleen
Splenic Infarct
Spleen
Torsion
Definitive diagnosis by ultrasound Characteristic appearance
– Severe, diffuse splenomegaly – Hypoechoic – Coarse & “lace-like” – Venous blood flow absent on Doppler – +/- hyperechoic venous thrombi
Lymphosarcoma can appear similar
– Normal blood flow
Spleen
Torsion
Spleen
Neoplasia
Lymphosarcoma
– Diffuse or focal/multifocal – Hypoechoic or hyperechoic – Can appear normal
Hematoma, hemangioma, hemangiosarcoma
– Unable to differentiate – Focal – Hypoechoic, hyperechoic or mixed
Spleen
Lymphosarcoma
Spleen
Hemangiosarcoma
Spleen
Neoplasia
Other neoplasms
– Mast cell tumor, leiomyoma, etc.
Presence of peritoneal effusion not a good indication of malignancy Metastasis
– Lungs, liver, lymph nodes (splenic, hepatic, gastric)
Spleen
Echogenic Focal Lesions
Focal fat deposits
– Especially cats – Surround hepatic veins (myelolipomas)
Fibrosis & calcification
– Secondary to hematoma, chronic infarcts or granulomas (histoplasmosis)
Primary or metastatic neoplasia
Spleen
Definitive Diagnosis
Ultrasonic appearance of most splenic diseases non-specific Consider history, signalment, clinical signs Fine needle aspirate useful Biopsy generally not performed
Spleen
Rupture
Free fluid within the abdomen
– Often echoic (due to blood cells) – May be anechoic
Most likely a tumor Cannot rule out hematoma
Spleen
Thrombosis
Spleen
Splenic Thrombus
Spleen
Myelolipoma