Splenomegaly Size Cutoff
Splenomegaly is defined as a spleen measuring greater than 13 cm in vertical length on imaging. 1, 2, 3
Standard Measurement Technique
The vertical length should be measured in the coronal plane, either on coronal CT images or by multiplying the number of spleen slices on transverse CT by slice thickness, or by measuring splenic coronal diameter on PET maximum intensity projection images. 1
This 13 cm threshold is established in the Lugano Classification and RECIL 2017 criteria for lymphoma response assessment, but is widely applied across clinical contexts. 1, 3
Clinical Grading of Splenomegaly
Mild splenomegaly: 11-13 cm in length 2
Clinically significant splenomegaly: >13 cm 2
Severe splenomegaly in myeloproliferative disorders: ≥5 cm below left costal margin, with particular concern when exceeding 15 cm below the left costal margin 1, 4
Alternative Single Measurement Cutoffs
While 13 cm coronal length is the standard, research supports alternative single measurements when coronal imaging is not optimal:
Craniocaudal length >9.5 cm can identify splenomegaly with good accuracy on CT. 5
Width >10.6 cm also correlates well with true splenomegaly. 5
Coronal oblique length ≥12 cm has 97.8% sensitivity but only 34.1% specificity for splenomegaly, making it useful for ruling out but not ruling in enlargement. 5
Important Caveats
Multidimensional indexes (craniocaudal × width × thickness) correlate better with actual splenic volume than single measurements (r = 0.95 vs r = 0.81), but are more time-consuming. 6
The spleen is typically not selected as a target lesion in lymphoma trials because size varies considerably in healthy individuals. 1
In pediatric populations, age-specific cutoffs must be used: 6.0 cm at 3 months, 7.0 cm at 12 months, 9.0 cm at 4 years, 11.0 cm at 10 years, and 12-13 cm by age 15 depending on sex. 7
Splenomegaly can be present even with normal imaging measurements in infiltrative processes like lymphoma, so clinical context matters. 8