Spleen and Lymphatic System

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Spleen: Anatomy & Imaging - Spleen Scene Setter

  • Location & Size: LUQ, intraperitoneal. Avg. 12x7x4 cm. Wt: ~150g.
    • 📌 Mnemonic "1,3,5,7,9,11": 1x3x5 inches, 7 oz, deep to ribs 9-11.
  • Vasculature: Splenic artery (from celiac trunk); Splenic vein (joins SMV → portal vein).
  • Imaging:
    • USG: Homogeneous, echogenic cf. liver.
    • CECT: Gold standard. Homogeneous enhancement. NECT: 40-60 HU.
    • MRI: T1 hypointense, T2 hyperintense. Portal and splenic veins 3D and axial CECT

⭐ Accessory spleen (splenunculus): Most common congenital anomaly, often at hilum; found in up to 30% of cases at autopsy/CT.

Splenomegaly & Diffuse Disease - The Swollen Spleen

  • Definition: Spleen length > 12-13 cm or weight > 200g.
  • Common Causes:
    • Congestive: Portal hypertension (cirrhosis), heart failure.
    • Infective: Malaria, Kala-azar, EBV, TB.
    • Hematological: Leukemias, lymphomas, hemolytic anemias, myeloproliferative disorders.
    • Storage: Gaucher's, Niemann-Pick.
    • Inflammatory: Sarcoidosis, SLE.
  • Imaging:
    • USG: Measures size, assesses echotexture. Doppler for portal flow.
    • CT/MRI: Confirms size, evaluates density/signal, aids in identifying cause. CT scan showing marked splenomegaly

⭐ In portal hypertension, USG may show dilated portal vein (>13mm), splenic vein (>10mm), collaterals, and ascites.

Focal Splenic Lesions - Spleen Spotting

  • Common Benign: Simple cyst, Hemangioma, Hamartoma.
  • Common Malignant: Lymphoma, Metastases (melanoma, lung, breast, ovary).
  • Infectious/Inflammatory: Abscess, Granulomas (TB, sarcoidosis).
LesionCECT AppearanceKey Differentiator(s)
Simple CystWater density (<20 HU), non-enhancingSharply marginated, anechoic on USG
HemangiomaPeripheral nodular enhancement, centripetal fillOften hyperechoic on USG
LymphomaHypodense, homogeneous, poor enhancementOften multiple, splenomegaly
MetastasesVariable, often hypovascularHistory of primary malignancy
AbscessRim-enhancing, central low attenuation, +/- gasClinical signs of infection (fever)

⭐ Splenic lymphoma is the most common malignant tumor of the spleen, often presenting as diffuse infiltration or multiple nodules rather than a single discrete mass.

Splenic Trauma - Spleen Under Siege

  • Most common: blunt trauma. CT is gold standard. Non-operative management (NOM) for stable patients.
  • AAST Splenic Injury Grading: | Grade | Description | |-------|-----------------------------------------------------------------------------| | I | Subcapsular hematoma <10%; Capsular tear <1cm | | II | Hematoma 10-50% or intraparenchymal <5cm; Laceration 1-3cm | | III | Hematoma >50% or ruptured; Intraparenchymal >5cm; Laceration >3cm | | IV | Laceration involving segmental/hilar vessels (>25% devascularization) | | V | Shattered spleen; Hilar vascular injury devascularizing spleen | AAST Splenic Injury Grading

⭐ Kehr's sign: referred left shoulder pain, may indicate splenic rupture due to diaphragmatic irritation.

Lymph Nodes & Lymphoma - Node Network News

  • Normal Nodes: Oval, fatty hilum. Short axis: Abdomen/Pelvis <10mm; Mesentery <5mm.
  • Benign vs. Malignant Node Features:
    FeatureBenignMalignant
    ShapeOval, reniformRound
    HilumFatty, preservedLost, effaced
    CalcificationGranulomatous (TB)Treated lymphoma, some mets
    NecrosisTB, suppurativeCommon, esp. high-grade
  • Lymphoma:
    • Bulky, homogeneous adenopathy; splenomegaly common.
    • NHL: Commoner, often extranodal. HL: Contiguous spread. CT scans showing lymphadenopathy in lymphoma
    • Ann Arbor Staging (Simplified):
      StageInvolvement
      ISingle LN region or single extralymphatic (IE)
      II≥2 LN regions, same side diaphragm
      IIIBoth sides diaphragm; +/- Spleen (S)
      IVDiffuse extralymphatic disease
    • B-symptoms: Fever, night sweats, wt loss >10%. E: Extranodal.

    ⭐ "Floating aorta sign" or "Sandwich sign": Mesenteric/retroperitoneal nodes encasing vessels, characteristic of lymphoma.

High‑Yield Points - ⚡ Biggest Takeaways

  • Splenomegaly (>12 cm length): common, due to portal hypertension, hematological disorders.
  • Splenic trauma: most common in blunt injury; note Kehr's sign, use AAST grading.
  • Splenic infarcts: wedge-shaped peripheral defects; causes include embolic, hematologic.
  • Accessory spleen (splenunculus): common congenital variant, usually near splenic hilum.
  • Lymphadenopathy (>1 cm short axis): suggests malignancy/infection; PET-CT for lymphoma staging.
  • Splenic calcifications: often from old granulomatous disease (TB) or healed infarcts.

Practice Questions: Spleen and Lymphatic System

Test your understanding with these related questions

Which of the following diseases does not typically present with fever, rash, and lymphadenopathy?

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Flashcards: Spleen and Lymphatic System

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_____ seen in X ray is a focal area of adynamic ileus close to an intra-abdominal inflammatory process

TAP TO REVEAL ANSWER

_____ seen in X ray is a focal area of adynamic ileus close to an intra-abdominal inflammatory process

Sentinel loop

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