Splenomegaly – Differential Diagnosis

Splenomegaly is typically defined as an enlarged spleen:

  • Weighing > 250 g
  • Width > 4-5 cm, diameter > 7 cm, and length > 11 cm in adults by ultrasound
  • Maximal craniocaudal dimension of 13 cm by computed tomography (CT)

Enlargement of the spleen occurs through one or more mechanisms (see following slides):

  • Work hypertrophy
  • Infiltration
  • Congestion

Other classification schemes include:

  • Massive vs. non-massive splenomegaly
  • Isolated splenomegaly or splenomegaly associated with other findings

Detecting splenomegaly:

Physical exam of spleen. Source.
Normal spleen on US. (a) Coronal and (b) axial views of the left upper quadrant show a normal spleen. The black line represents the splenic width, the white line in (a) represents the splenic length and the white line in (b) indicates the splenic depth. Source: Singapore Med J 2015; 56(3): 133-144.
CT scan of isolated splenomegaly in a patient with non-Hodgkin lymphoma is most likely secondary to splenic involvement. Source: https://radiopaedia.org/articles/splenomegaly
Coronal CT of the abdomen demonstrating a markedly enlarged spleen (asterisk). The combination of osteosclerosis and massive splenomegaly has a narrow differential diagnosis and is most suggestive of myelofibrosis. Source: Insights Imaging. 20191:71.

Splenomegaly may be classified several ways:

  • According to prevalence; most common causes include:
    • Hematologic (especially hematologic malignancy)
    • Hepatic
    • Infection
  • According to mechanism
    • Increased splenic function (work hypertrophy), resulting from excessive function of normal splenic activities such as:
      • RBC sequestration (reticuloendothelial system hypertrophy), as seen in:
        • Hemoglobinopathies
        • Membranopathies
      • Immune-mediated hyperplasia, as seen in
        • Infections
          • Viral
            • CMV
            • EBV
            • Hepatitis
          • Bacteria
            • Brucellosis
            • Tickborne disease
            • Tb
          • Fungal
          • Parasitic
            • Visceral leishmaniasis
            • Malaria
            • Echinococcosis
            • Schistosomiasis 
        • Chronic inflammation
          • Chronic autoimmune disorders
            • ITP
            • AIHA
            • SLE
            • RA
            • Felty syndrome
          • Sarcoidosis
          • HLH
          • Hyperthyroidism
      • Extramedullary hematopoiesis, as seen in essential thrombocythemia, polycythemia vera, and primary and secondary myelofibrosis.
    • Infiltration involving abnormal intracellular or extracellular deposition of substances in the spleen secondary to:
      • Neoplasms
        • Lymphoma
        • Leukemia
          • ALL
          • CML
          • HCL
          • WM
        • Metastatic lesions
        • Primary vascular neoplasms of the spleen
          • Benign
            • Hemangiomas
            • Lymphangioma 
            • Hamartomas
            • Littoral cell angiomas
          • Malignant – angiosarcoma
      • Metabolic conditions
        • Primary amyloidosis
        • Glycogen storage disease
        • Rosai-Dorfman disease
        • Gaucher disease
      • Pseudocysts or true cysts
      • Splenic abscesses
        • Bacterial
        • Parasitic
        • Mycotic
    • Passive congestion due to obstruction of venous blood flow; for example cirrhosis with portal hypertension, heart failure, and splenic/portal/hepatic vein thrombosis.
  • According to whether the splenomegaly is massive (not precisely defined radiologically, but usually defined as clinically palpable > 8 cm below left costal margin or when the lower spleen pole is within the pelvis or when the spleen crosses the midline), seen most commonly in:
    • hematological disorders
      • Chronic myeloid leukemia
      • Agnogenic myeloid metaplasia
      • Polycythemia vera
      • Essential thrombocythemia
      • Indolent lymphomas
      • Hairy cell leukemia
      • Beta-thalassemia major
    • Infectious diseases
      • Kala-azar (visceral leishmaniasis)
      • Malaria
    • infiltrative conditions
      • Gaucher disease
      • Primary angiosarcoma of the spleen
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