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:
