Differential Diagnosis

The patient's presentation of lethargy, slightly enlarged spleen, and abnormal blood work suggests a hematological disorder. The following differential diagnoses are considered:

• Single most likely diagnosis
  • Beta-Thalassemia Major: The patient's low MCV (52.7 fL) and elevated WBC count (13.0 X10^3 cells/µL) are consistent with beta-thalassemia major. The disease is characterized by a reduction in the production of the beta-globin chains of hemoglobin, leading to severe anemia, splenomegaly, and other complications.
• Other Likely diagnoses
  • Alpha-Thalassemia: Although less likely than beta-thalassemia major, alpha-thalassemia could also present with microcytic anemia and splenomegaly. However, the MCV is typically more severely reduced in alpha-thalassemia.
  • Iron Deficiency Anemia: The patient's microcytic anemia (low MCV) could be consistent with iron deficiency anemia. However, the elevated WBC count and splenomegaly are not typical of iron deficiency anemia.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sickle Cell Disease: Although the patient's symptoms and lab results do not strongly suggest sickle cell disease, it is a critical diagnosis to consider due to its potential severity and the need for prompt treatment.
  • Leukemia: The patient's elevated WBC count and splenomegaly could be indicative of leukemia, which would require immediate attention and treatment.
• Rare diagnoses
  • Other Hemoglobinopathies: Other rare hemoglobinopathies, such as hemoglobin C or E disease, could also present with microcytic anemia and splenomegaly.
  • Congenital Dyserythropoietic Anemia: This rare group of disorders is characterized by anemia, splenomegaly, and distinct morphological features on peripheral blood smear.

Given the Hb electrophoresis results, one would expect to see:

• Definite: Target cells on the peripheral blood smear, which are characteristic of hemoglobinopathies such as beta-thalassemia major.
• Variable: Variable degrees of anisopoikilocytosis (unequal size and shape of red blood cells) and basophilic stippling, which can be seen in various hematological disorders, including thalassemia and other hemoglobinopathies.

The Final Diagnosis/Interpretation is beta-thalassemia major, which is consistent with the patient's microcytic anemia (low MCV) and other laboratory findings. The reason for the low MCV in this case is the reduced production of beta-globin chains, leading to an imbalance in hemoglobin synthesis and the formation of small, immature red blood cells.