Major lymphatic vessels and nodal chains lie along major blood vessels (aorta, inferior vena cava, iliac)

Lymph nodes carry same name as vessel they accompany

Lymph from alimentary tract, liver, spleen, and pancreas passes along celiac, superior mesenteric chains to nodes

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  Efferent vessels from alimentary nodes form intestinal lymphatic trunks

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  Cisterna chyli (chyle cistern)

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    Formed by confluence of intestinal lymphatic trunks and right and left lumbar lymphatic trunks, which receive lymph from nonalimentary viscera, abdominal wall, and lower extremities

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    May be discrete sac or plexiform convergence

Thoracic duct: Inferior extent is chyle cistern at L1-L2 level

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  Formed by convergence of main lymphatic ducts of abdomen

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  Ascends through aortic hiatus in diaphragm to enter posterior mediastinum

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  Ends by entering junction of left subclavian and internal jugular veins

Lymphatic system drains surplus fluid from extracellular spaces and returns it to bloodstream

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  Important function in defense against infection, inflammation, and tumor via lymphoid tissue present in lymph nodes, gut wall, spleen, and thymus

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  Absorbs and transports dietary lipids from intestine to thoracic duct and bloodstream

Lymph nodes

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  Composed of cortex and medulla

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  Invested in fibrous capsule, which extends into nodal parenchyma to form trabeculae

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  Internal honeycomb structure filled with lymphocytes that collect and destroy pathogens

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  Hilum: In concave side, with artery and vein, surrounded by fat

Preaortic nodes

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  Celiac nodes: Drainage from gastric nodes, hepatic nodes, and pancreaticosplenic nodes

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  Superior and inferior mesenteric nodes: Drainage from mesenteric nodes

Lateral aortic (paraaortic/paracaval) nodes

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  Drainage from kidneys, adrenal glands, ureter, posterior abdominal wall, testes and ovary, uterus, and fallopian tubes

Retroaortic nodes

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  Drainage from posterior abdominal wall

External iliac nodes

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  Primary drainage from inguinal nodes

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  Flow into common iliac nodes

Internal iliac nodes

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  Drainage from inferior pelvic viscera, deep perineum, and gluteal region

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  Flow into common iliac nodes

Common iliac nodes

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  Drainage from external iliac, internal iliac, and sacral nodes

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  Flow into lumbar (lateral aortic) chain of nodes

Superficial inguinal nodes

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  In superficial fascia parallel to inguinal ligament, along cephalad portion of greater saphenous vein

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  Receive lymphatic drainage from superficial lower extremity, superficial abdominal wall, and perineum

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  Flow into deep inguinal and external iliac nodes

Deep inguinal nodes

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  Along medial side of femoral vein, deep to fascia lata and inguinal ligament

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  Receive lymphatic drainage from superficial inguinal and popliteal nodes

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  Flow into external iliac nodes

CT is test of choice for cancer staging

May be supplemented by PET/CT in select cancers

US may be useful in children or thin adults

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  Normal nodes are elliptical with echogenic fatty hilum and uniform hypoechoic cortex

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  Normal lymph nodes rarely detected on abdominal US

Normal diameter of lymph node varies depending on location

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  Short-axis diameter

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    Abdominopelvic < 10 mm

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    Hepatogastric ligament < 8 mm

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    Retrocrural < 6 mm

Transducer: 2-5 MHz or 5-9 MHz for thinner adult patients

Patient examined in supine position with > 4 hours of fasting to decrease bowel gas

Graded compression technique to clear overlying bowel loops

Nodal enlargement is nonspecific, may be neoplastic, inflammatory, or reactive

Normal-sized lymph nodes may harbor metastatic malignancy

Node morphology is more specific for pathology

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  Abnormal nodes have replacement or loss of fatty hilum

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  Look for central necrosis, cystic change, or calcification

Lymphoma

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  Multiple enlarged hypoechoic or anechoic nodes

Metastatic lymphadenopathy

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  More echogenic and heterogeneous nodes compared to lymphomatous nodes

Infectious/reactive lymphadenopathy

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  Nonspecific sonographic features

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  May contain necrotic centers in mycobacterial infection