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Infraclavicular lymph nodes

The infraclavicular lymph nodes are a small but clinically important group of lymph nodes situated in the deltopectoral groove beneath the clavicle, often along the course of the cephalic vein as it drains into the axillary vein. They are part of the axillary lymphatic system, specifically classified as level III axillary nodes in breast cancer staging. Though fewer in number compared to other axillary groups, they play a critical role in draining lymph from the upper limb, shoulder, and portions of the breast.

These nodes serve as an intermediate drainage station between the lateral (humeral) axillary nodes and the apical axillary nodes, and can be a site of metastasis or lymphatic spread in cancers of the upper limb and breast.

Synonyms

  • Deltopectoral lymph nodes

  • Infraclavicular axillary nodes

  • Level III axillary lymph nodes

Function

  • Drain lymph from the upper limb (especially lateral arm via cephalic vein)

  • Receive lymph from humeral (lateral) axillary nodes and pass it to the apical axillary group

  • Act as immune surveillance centers, filtering pathogens and tumor cells

  • Serve as sentinel nodes in breast cancer staging and melanoma

MRI Appearance

T1-weighted images:

  • Normal nodes appear as small, oval, low-to-intermediate signal cortex with a central hyperintense fatty hilum

  • Pathological nodes appear rounder, enlarged, hypointense, and often lose their fatty hilum

T2-weighted images:

  • Normal nodes: intermediate cortex with bright fatty hilum

  • Inflammation or metastasis produces hyperintense signal, with irregular margins or heterogeneous appearance

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, making nodes more conspicuous against the dark background of the deltopectoral fat plane

  • Normal nodes: low-to-intermediate signal

  • Pathological nodes (metastatic, inflamed): bright hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal nodes: homogeneous enhancement with preserved fatty hilum

  • Malignant nodes: heterogeneous or rim enhancement, cortical thickening, and loss of central hilum

  • Useful for differentiating benign vs. malignant nodal enlargement

CT Appearance

Non-contrast CT:

  • Infraclavicular nodes appear as small soft tissue density nodules in the deltopectoral groove or beneath the clavicle

  • Benign nodes: oval with fatty hilum, usually <1 cm short-axis

Contrast-enhanced CT (CECT):

  • Normal nodes: enhance mildly and homogeneously

  • Malignant nodes: rounded, loss of hilum, heterogeneous or rim enhancement, possible necrosis

  • CT helps assess nodal involvement in breast cancer, melanoma, and lymphoma

MRI images

Infraclavicular lymph nodes anatomy mri axial image -img-00000-00000

CT image

Infraclavicular lymph nodes anatomy CT axial image -img-00000-00000