Splenomegaly (enlarged spleen)

Mechanisms

Major mechanisms include congestive enlargement from portal hypertension or venous outflow obstruction; hyperplasia of lymphoid or reticuloendothelial tissue (reactive or neoplastic); infiltration by malignant cells or storage products; and extramedullary hematopoiesis when bone marrow is inadequate. Persistent enlargement can be mild, moderate, or massive depending on cause and duration.

Common causes

• Infections: viral (notably Epstein–Barr virus), bacterial causes, parasitic diseases such as malaria, and chronic infections.
• Hematologic disorders: leukemias, lymphomas, myeloproliferative neoplasms, hemolytic anemias, and thalassemia syndromes.
• Congestive splenomegaly associated with portal hypertension and advanced liver disease.
• Infiltrative and storage diseases: for example, Gaucher and other lysosomal storage disorders, and amyloidosis.
• Autoimmune and inflammatory conditions and disorders causing extramedullary hematopoiesis.

Presentation and evaluation

Many patients are asymptomatic; others report fullness or pain in the left upper quadrant, early satiety, or symptoms related to cytopenias such as fatigue, bleeding, or infections. On examination the spleen may be palpable or percussible below the left costal margin. Laboratory testing includes a complete blood count with smear, liver tests, infection serologies, and targeted studies guided by history. Ultrasound is the usual first-line imaging; CT or MRI can further characterize size and texture. Bone marrow examination or targeted histology may be needed to identify hematologic or infiltrative causes.

Treatment and complications

Management targets the underlying diagnosis: antimicrobial therapy for infections, disease‑directed oncology treatments, or measures to reduce portal pressure in congestive states. When splenomegaly causes severe symptoms, significant cytopenias from sequestration, or diagnostic uncertainty, options include splenectomy, partial splenic resection, or radiologic splenic artery embolization. Splenectomy reduces cytopenias but increases lifelong risk of serious infection and alters thrombosis risk; appropriate vaccinations (against encapsulated organisms) and patient education are essential. Acute complications include splenic rupture and hemorrhage, and chronic issues include hypersplenism and hematologic sequelae.

Clinical assessment should distinguish acute from chronic causes and identify life‑threatening presentations promptly; multidisciplinary care often involves hematology, infectious disease, and surgery.