What is Organomegaly?
Organomegaly refers to the abnormal enlargement of internal organs, most commonly involving the liver (hepatomegaly), spleen (splenomegaly), and/or lymph nodes (lymphadenopathy). 1
Clinical Definition and Assessment
Organomegaly is formally defined by imaging rather than physical examination alone, as the sensitivity of physical examination varies significantly among observers. 1
Specific organ enlargement criteria:
- Hepatomegaly: Clinically enlarged liver extending beyond the costal margin in the midclavicular line, confirmed by imaging studies 1
- Splenomegaly: Palpable spleen or spleen longitudinal diameter ≥13 cm on imaging 1
- Lymphadenopathy: Significant adenopathy defined as lymph nodes >1 cm in diameter 1
Clinical Significance in Disease Staging
Organomegaly serves as a critical staging and prognostic parameter across multiple hematologic malignancies:
In chronic lymphocytic leukemia (CLL), organomegaly determines Binet staging classification. Stage B disease requires 3 or more areas of nodal or organ enlargement (including palpable liver and spleen), while maintaining hemoglobin ≥100 g/L and platelets ≥100 × 10⁹/L. 1
In hemophagocytic lymphohistiocytosis (HLH), organomegaly is incorporated into the HScore diagnostic algorithm, where hepatomegaly alone scores 23 points, splenomegaly alone scores 23 points, and combined hepatosplenomegaly scores 38 points. 1
In plasma cell leukemia, patients exhibit higher prevalence of organomegaly with involvement of liver, spleen, lymph nodes, and extramedullary plasmacytomas compared to multiple myeloma, reflecting the more aggressive clinical presentation. 1
Prognostic Impact
The number of organomegalies present directly correlates with survival outcomes. In systemic mastocytosis, overall survival worsens progressively: patients with no organomegaly versus one organomegaly (HR 4.9,95% CI 3.4-7.1, P<0.001); one versus two organomegalies (HR 2.1,95% CI 1.4-3.1, P<0.001); and two versus three organomegalies (HR 1.7,95% CI 1.2-2.5, P=0.004). 2
New occurrence of organomegaly during follow-up indicates disease progression in 38-43% of patients with various forms of systemic mastocytosis. 2
Common Etiologies
The most common causes of organomegaly in the United States are liver disease, malignancy, and infection. 3
Specific disease associations include:
- Liver disease with portal hypertension: Leading cause of splenomegaly 4
- Hematologic malignancies: Leukemias and lymphomas, often with concurrent lymphadenopathy 4
- Infections: Including infectious mononucleosis domestically; malaria and schistosomiasis affect up to 80% of people in tropical regions 3
- Lysosomal storage diseases: Gaucher's disease and mucopolysaccharidoses cause infiltrative organomegaly 4, 5
- Hemolytic syndromes: Chronic hemolysis leads to splenic enlargement 4
Diagnostic Approach
Initial imaging should utilize abdominal ultrasound for confirmation and assessment of organ size, texture, and focal lesions. 6 CT scanning is indicated for staging confirmed malignancy, evaluating deep or mediastinal nodes, and assessing surrounding structures. 7
Laboratory evaluation must include:
- Complete blood count with differential 7
- Liver function tests (total bilirubin, AST, ALT, alkaline phosphatase, GGT, platelet count) 6
- HIV testing if status unknown 7
- Hepatitis B and C serologies if immunosuppressive therapy is planned 7
Clinical Complications
Acute infections, anemia, and splenic rupture represent the most common complications of splenomegaly. Patients should refrain from contact sports to decrease rupture risk. 3
Patients with functional or anatomic asplenia require increased vaccination coverage and prophylactic antibiotics for respiratory tract procedures. 3