Splenomegaly

 Splenomegaly ( enlargement of the spleen) is a common finding in various systemic diseases.

 Anatomy of the spleen

Location & external appearance

• The spleen lies in the left upper quadrant (LUQ) of the abdomen, tucked under the left hemidiaphragm and posterolateral to the stomach (typically between ribs 9–11). It projects into the left hypochondrium.

Size & weight

• Normal adult spleen: roughly 8–12 cm in long axis, and weight ~70–200 g. Spleen weight ≈ 400–500 g indicates splenomegaly; >1000 g is commonly described as massive splenomegaly.

Internal structure

• Encapsulated organ composed of red pulp (venous sinusoids, splenic cords filtration and removal of aged/abnormal RBCs) and white pulp (periarteriolar lymphoid sheaths and follicles  immune function). The interface (marginal zone) is important for antigen capture and phagocytosis.

          Vascular supply & lymphatic drainage

• Arterial supply: splenic artery (branch of the celiac trunk) enters at the hilum; divides into segmental branches.
• Venous drainage: splenic vein  portal vein (joins with superior mesenteric vein). Splenic enlargement often influences portal hemodynamics and portal hypertension physiology.
• Lymphatics: drain to pancreaticosplenic and splenic hilar nodes and then to celiac nodes.

2. Pathophysiology of splenomegaly

Definition

• Splenomegaly  abnormal enlargement of the spleen; clinically detected by palpation, imaging, or at surgery/autopsy. It’s a sign, not a diagnosis, and reflects several underlying pathophysiologic processes.
•  Mechanisms that lead to enlargement
  Broad mechanisms (often overlapping) include:

1. Hyperplasia of splenic tissue (white pulp / reticuloendothelial proliferation) — e.g., immune stimulation with lymphoid hyperplasia (chronic infections, autoimmune disease, some lymphomas).
2. Congestion / vascular pooling (red pulp expansion)  from portal hypertension or splenic vein outflow obstruction; causes increased sequestration of blood elements.
3. Infiltration by cells/materials  storage disorders (Gaucher, Niemann–Pick), leukemic/lymphomatous infiltration, or granulomatous disease.
4. Increased work (hyperfunction)  hemolytic states or immune-mediated destruction leading to compensatory splenic enlargement and hyperactivity (hypersplenism).

Physiological changes in splenomegaly

• Red pulp expansion  increased pooling/sequestration of RBCs, platelets and leukocytes  cytopenias (anemia, thrombocytopenia, leukopenia) from hypersplenism.
• Altered immune function  may be hyperactive (increased clearance of opsonized organisms) or dysfunctional (predisposition to particular infections post-splenectomy or with functional asplenia).
• Mechanical effects   left upper quadrant pain/fullness, early satiety from gastric compression, and increased risk of traumatic rupture when large.

3. Causes of splenomegaly (categorized)

        lists below are illustrative. Many conditions overlap categories.

A. Infectious

• Acute/Chronic bacterial: infective endocarditis, subacute bacterial infections.
• Viral: EBV (infectious mononucleosis), CMV, hepatitis viruses, HIV.
• Parasitic: malaria, visceral leishmaniasis (kala-azar).
• Others: brucellosis, typhoid (enteric fever).

B. Hematologic

• Hemolytic anemias: hereditary spherocytosis, autoimmune hemolytic anemia, thalassemia (esp. intermediate/major).
• Hypersplenism: secondary to many disorders causing cytopenias.
• Congenital hemoglobinopathies (sickle cell disease early/functional changes).

C. Neoplastic / hematologic malignancies

• Lymphoid: non-Hodgkin lymphoma (esp. splenic marginal zone lymphoma), chronic lymphocytic leukemia (CLL), hairy cell leukemia.
• Myeloid / myeloproliferative neoplasms: primary myelofibrosis, polycythemia vera, chronic myeloid leukemia (CML).
• Metastatic disease or primary splenic neoplasms (rare). Recent cohorts show lymphomas and myeloproliferative disorders are common causes of massive splenomegaly.

D. Metabolic / storage / infiltrative

• Lysosomal storage diseases: Gaucher disease, Niemann–Pick, amyloidosis, sarcoidosis infiltration causes progressive enlargement.

E. Inflammatory / autoimmune

• Systemic lupus erythematosus (SLE), rheumatoid arthritis (Felty syndrome  RA + neutropenia + splenomegaly), inflammatory bowel disease (rarely).

F. Vascular / portal hypertensive

• Portal hypertension from chronic liver disease  congestive splenomegaly with varices, hypersplenism. Splenic vein thrombosis (e.g., pancreatitis-associated) causes segmental enlargement.

G. Trauma / rupture

• Traumatic enlargement / hematoma leading to tender splenomegaly; risk of rupture.

4. Management of splenomegaly

Diagnostic approach

A. History

• Onset (acute vs chronic), systemic symptoms (fever, weight loss, night sweats), travel (malaria, leishmaniasis), exposure (animals, ticks), blood transfusion history, alcohol use, prior liver disease, bleeding/bruising, constitutional symptoms, family history (hereditary hemolytic disorders), drugs.

B. Physical examination

• Palpate LUQ: classically a palpable spleen moves downward with inspiration; percussion can show dullness (Traube’s space). Look for hepatomegaly, lymphadenopathy, stigmata of chronic liver disease, signs of hemolysis (jaundice), petechiae/bleeding.

C. Basic laboratory tests

• CBC with differential (looking for cytopenias, leuko- or lymphocytosis).
• Peripheral blood smear (spherocytes, schistocytes, leukoerythroblastic picture).
• Reticulocyte count, LDH, bilirubin, haptoglobin (hemolysis workup).
• Liver function tests, coagulation profile (for portal hypertension/liver disease).
• Infectious workup as indicated: EBV serology, CMV, HIV, malaria smear/rapid tests, blood cultures.
• Autoimmune serology (ANA/ENA) if indicated.
• Bone marrow biopsy if cytopenias or suspicion of marrow/infiltrative disorder.

D. Imaging

• Ultrasound: first-line to confirm enlargement and assess echotexture; measures length and volume.
• Contrast CT scan (abdomen) for more detailed anatomy, focal lesions, evaluation of splenic vein/portal system, and to assess for trauma.
• MRI if further characterization or when CT contraindicated.

E. Directed tests

• Serologies for specific infections, hemoglobin electrophoresis (thalassemia), genetic tests for storage disorders, PET-CT if lymphoma suspected, bone marrow cytogenetics/molecular studies for myeloproliferative neoplasms (JAK2, CALR, MPL).

Treatment — principles & examples

Treatment is directed at the underlying cause; supportive care for complications of splenomegaly (e.g., cytopenias, pain, rupture risk).

1. Medical / disease-specific

• Infections: treat specific agent (antimalarials, amphotericin/antileishmanial therapies, antibiotics for bacterial infections, antiviral therapy/supportive for EBV/CMV).
• Hematologic disorders:

·         Autoimmune hemolytic anemia — corticosteroids, immunosuppression, rituximab as indicated; splenectomy may be considered for refractory cases.

·         Myeloproliferative neoplasms — JAK inhibitors (e.g., ruxolitinib) for myelofibrosis can reduce splenic size and symptoms; disease-specific therapy for CML (TKIs).

• Storage diseases: enzyme replacement (e.g., Gaucher) or substrate reduction therapy when available.
• Portal hypertension: treat underlying liver disease; consider portal pressure–directed therapies and variceal management. Splenic artery embolization may be used in select settings to reduce spleen size/sequestration and control bleeding risk.

2. Interventional / surgical

• Splenectomy (open or laparoscopic) — indications include: diagnostic uncertainty (rare), symptomatic massive splenomegaly causing pain/early satiety, refractory cytopenias from hypersplenism (when medical therapy fails), certain hematologic diseases (e.g., refractory immune thrombocytopenia, hereditary spherocytosis), or trauma with rupture and hemodynamic instability.

Risks: perioperative bleeding, pancreatic injury, venous thromboembolism, and long-term increased risk of overwhelming post-splenectomy infection (OPSI) from encapsulated organisms.

Partial splenic embolization or splenic artery embolization  options to decrease sequestration in patients who are poor surgical candidates or to temporize (e.g., portal hypertensive bleeding).

3. Peri- and post-splenectomy preventive care

• Vaccinations: essential for asplenic or hyposplenic patients. Recommended vaccines include pneumococcal (PCV13/15/20 and/or PPSV23 per local schedule), meningococcal (MenACWY and MenB), and Haemophilus influenzae type b (Hib) — ideally given ≥14 days before elective splenectomy; if emergency, give as soon as clinically possible post-op and follow schedule. Annual influenza vaccination is also recommended. Patient-specific timing and boosters depend on prior vaccine history and local guidance.
• Antibiotic prophylaxis: many centers recommend postop oral antibiotics (e.g., penicillin) for certain durations for children; adult strategies vary  educate patients to seek urgent care for fever and consider standby antibiotics in some high-risk patients.

4. Symptom management & monitoring

• Analgesia for LUQ pain, counseling to avoid contact sports or activities with high rupture risk if spleen markedly enlarged. Regular monitoring of CBC, imaging if clinically indicated, and vigilance for infection signs.

Patient education & follow-up considerations

• Explain that splenomegaly is a sign: workup aims to identify a treatable underlying cause.
• Warn about infection risk if spleen removed or non-functional  provide vaccine schedule, educate about febrile illness as an emergency (seek immediate care for fever >38.5°C / 101.3°F), and consider medical alert identification noting asplenia.
• Discuss lifestyle precautions (avoid high-risk contact sports while spleen is large), and inform about long-term follow-up (CBCs, disease-specific monitoring). Document the indication and ensure communication between specialists (hematology, infectious disease, surgery).

Key takeaways

1. Splenomegaly is a sign, produce a targeted workup (history, exam, CBC, smear, ultrasound/CT, disease-specific tests).
2. Mechanisms: hyperplasia, congestion, infiltration, or increased work  each mechanism guides likely causes and investigations.
3. Treat the underlying cause; reserve splenectomy for refractory, symptomatic, or specific diagnostic/therapeutic indications.
4. Vaccination and infection education are critical for anyone who will undergo splenectomy or has functional hyposplenism.