Idiopathic Thrombocytopenic Purpura (ITP) is Associated with a Normal-Sized Spleen
The correct answer is (a) idiopathic thrombocytopenic purpura, as ITP characteristically presents with a normal-sized spleen, and the presence of splenomegaly should prompt consideration of alternative diagnoses.
Spleen Size in ITP
In adults with ITP, the spleen is typically not palpable and remains normal in size. 1 The American Society of Hematology guidelines emphasize that while splenomegaly may be slightly more common in children with ITP (particularly infants), with the spleen being palpable in approximately 12% of pediatric cases, this is still the minority of patients. 1
When splenomegaly is detected on physical examination in a patient with suspected ITP, abdominal CT or ultrasound is recommended to investigate alternative diagnoses. 2 The presence of significant splenomegaly should raise suspicion for conditions other than ITP.
Why Other Conditions Typically Have Splenomegaly
The other conditions listed characteristically present with splenomegaly:
Gaucher's disease causes massive splenomegaly due to accumulation of glucocerebroside-laden macrophages (Gaucher cells) in the spleen, making it one of the hallmark features of this lysosomal storage disorder.
Thalassemia results in splenomegaly from chronic hemolysis, extramedullary hematopoiesis, and sequestration of abnormal red blood cells, with the spleen often becoming markedly enlarged.
Schistosomiasis causes hepatosplenic disease with significant splenomegaly due to portal hypertension from periportal fibrosis and granulomatous inflammation.
Myelodysplasia can present with splenomegaly, particularly in cases with associated myeloproliferative features or when there is extramedullary hematopoiesis.
Clinical Implications for Diagnosis
The absence of splenomegaly is an important diagnostic feature supporting ITP. 1 When evaluating a patient with thrombocytopenia, the physical examination should specifically assess for spleen size, as a palpable spleen suggests alternative diagnoses such as lymphoproliferative disorders, myeloproliferative neoplasms, storage diseases, or infectious causes. 2
ITP remains a diagnosis of exclusion characterized by isolated thrombocytopenia with normal red and white blood cell morphology on peripheral smear and a normal-sized spleen. 1, 2