Evaluation of Splenomegaly in a 15-Year-Old Male

Initial Evaluation and Diagnosis

The American Academy of Pediatrics recommends proceeding immediately with complete blood count with differential, peripheral blood smear review, comprehensive metabolic panel, and abdominal ultrasound to confirm splenomegaly and evaluate for hematologic malignancy or other serious causes 1
Abdominal ultrasound should be obtained to confirm splenomegaly (normal spleen length <11 cm; mild splenomegaly 11-13 cm; clinically significant >13 cm) and assess for focal lesions or hepatomegaly 1, 2
Physical examination should document the exact spleen size below the costal margin, as pediatric patients with hematologic disorders frequently present with larger spleens than adults 3

Complete blood count with differential should be performed to identify cytopenias, leukocytosis, lymphocytosis, or abnormal cell populations that suggest hematologic malignancy 1
Peripheral blood smear review is critical to identify atypical lymphocytes (>10% suggests infectious mononucleosis despite negative monospot), blasts, or other abnormal cells suggestive of leukemia or lymphoma 1
Comprehensive metabolic panel including liver function tests should be obtained, as elevated transaminases can occur with infectious mononucleosis even when heterophile antibody is negative, and hepatomegaly suggests hematologic disorders 1
Lactate dehydrogenase (LDH) should be tested to screen for hemolysis or malignancy 1
Flow cytometry of peripheral blood for immunophenotyping should be performed if lymphoproliferative disorder is suspected based on CBC findings 1

Lymphoproliferative disorders (lymphoma, leukemia) are suggested by anemia, leukocytosis with lymphocytosis, and hepatosplenomegaly in this age group 2
Chronic myeloid leukemia (CML) should be considered, as pediatric CML-CP presents with high leukocyte counts, splenomegaly (often larger than in adults), and mild anemia 3
Bone marrow aspiration and biopsy should be performed if abnormal cells are found in peripheral blood, unexplained cytopenias are present, or myeloproliferative/lymphoproliferative disorder is suspected 1
Myeloproliferative neoplasms should be considered; testing for JAK2, CALR, and MPL mutations is recommended if this is suspected 1, 2
Sickle cell disease with splenic sequestration presents with rapidly enlarging spleen and hemoglobin decrease >2 g/dL below baseline, though this typically occurs in younger children 4

CT or MRI of the abdomen should be considered if ultrasound findings are equivocal or if lymphadenopathy needs further characterization 1
Advanced imaging can help identify focal splenic lesions, assess for lymphadenopathy, and evaluate liver involvement 1

Immediate hematology referral is warranted if peripheral smear shows blasts, abnormal lymphocytes beyond typical reactive changes, or if cytopenias are present 1
Lymph node biopsy should be performed if lymphadenopathy is present and lymphoma is suspected 1
For suspected CML, conventional cytogenetics, FISH, and/or RT-PCR to detect tyrosine kinase fusion gene rearrangements is recommended 1
Assess for signs of splenic complications including acute splenic sequestration (rapid enlargement with hemoglobin drop) or impending rupture (abdominal pain, left shoulder pain) 4