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Superficial inguinal lymph nodes

The superficial inguinal lymph nodes are a group of lymph nodes located in the superficial fascia of the groin, just inferior to the inguinal ligament. They are arranged in two major groups, horizontal and vertical, and play a key role in lymphatic drainage of the lower limb, perineum, and external genitalia. These nodes are clinically significant because enlargement may indicate local infection, systemic disease, or malignancy, and they are routinely assessed in oncology staging and physical examination of the groin.

Synonyms

  • Superficial groin lymph nodes

  • Horizontal and vertical inguinal nodes

  • Inguinal superficial nodal group

Location and Groups

  • Found in the superficial fascia of the groin, parallel and inferior to the inguinal ligament

  • Divided into:

    • Horizontal group: Arranged parallel to the inguinal ligament; drain lower abdominal wall, perineum, and external genitalia

    • Vertical group: Located along the termination of the great saphenous vein; drain skin and superficial tissues of lower limb

Relations

  • Anteriorly: Skin and subcutaneous tissue of groin

  • Posteriorly: Fascia lata and femoral vessels (deeper structures)

  • Superiorly: Inguinal ligament

  • Inferiorly: Upper thigh and termination of great saphenous vein

  • Medially: Pubic tubercle

  • Laterally: Anterior superior iliac spine (ASIS)

Function

  • Drain lymph from:

    • Skin and superficial fascia of lower abdominal wall (below umbilicus)

    • Perineum and external genitalia (except testes)

    • Gluteal region (partially)

    • Superficial tissues of the lower limb via great saphenous vein territory

  • Act as filtration centers for pathogens, tumor cells, and cellular debris

  • Participate in immune surveillance

Clinical Significance

  • Enlargement due to infection, trauma, or malignancy (e.g., melanoma, vulvar, penile, anal cancers)

  • Commonly palpable on physical exam

  • Sentinel node mapping in cancers (e.g., penile, vulvar melanoma)

  • May be confused with femoral hernia or other groin masses

  • Important in oncology staging and surgical planning

MRI Appearance

T1-weighted images:

  • Nodes show low-to-intermediate signal intensity

  • Fatty hilum appears bright if preserved

  • No fluid: nodes remain solid and well-defined

T2-weighted images:

  • Nodes show intermediate-to-bright signal intensity

  • Reactive/inflamed nodes often appear more hyperintense

  • Fat around nodes appears bright

STIR (Short Tau Inversion Recovery):

  • Nodes demonstrate intermediate to bright signal

  • Inflamed or malignant nodes: bright hyperintensity with loss of fatty hilum

  • Fat suppressed and appears dark, improving nodal conspicuity

T1 Fat-Sat Post-Contrast:

  • Normal nodes: mild homogeneous enhancement

  • Malignant nodes: heterogeneous or irregular enhancement

  • Abscessed/necrotic nodes: rim enhancement with central non-enhancing necrosis

CT Appearance

Non-Contrast CT:

  • Nodes appear as soft tissue density nodules in groin

  • Fatty hilum: central low density (if present)

  • Enlarged nodes: solid, homogeneous, loss of hilum

  • Fat planes around nodes provide contrast

Post-Contrast CT:

  • Normal nodes: mild homogeneous enhancement

  • Reactive nodes: uniform but more prominent enhancement

  • Malignant/necrotic nodes: heterogeneous or rim enhancement with central low attenuation

  • Surrounding fat may show stranding in infection or inflammation

MRI image

Superficial inguinal lymph nodes MRI axial anatomy image 0

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Superficial inguinal lymph nodes ct axial image

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Superficial inguinal lymph nodes ct coronal image