A four year old boy was admitted with a history of abdominal pain and fever for two months maculopapular rash for ten days, and dry cough, dyspnea and wheezing for three days. On examination liver and spleen were enlarged 4 cm and 3 cm respectivley below the costal margin. His hemoglobin was 10.0 g/dl, platelet count 3.7 x 1091L and total leukocyte count 70 x 109/L, which included 80% eosinophils Bone marrow examination revealed a cellular marrow comprising of 45% blasts and 34% Eosinophils and eosinophil precursors. The blasts stained negative for my eloperoxidase and nonspecific esterase and were positive for CD19, CD10, CD22 and CD20. Which one of the following statements is not true about disease?

**Core Concept**
The patient's presentation suggests a hematological malignancy, specifically acute lymphoblastic leukemia (ALL) with a unique feature of eosinophilia. The bone marrow examination reveals a predominance of blasts expressing B-cell markers, indicating a B-cell lineage ALL.

**Why the Correct Answer is Right**
The presence of 45% blasts in the bone marrow is diagnostic of ALL. The expression of CD19, CD10, CD22, and CD20 on the blasts confirms a B-cell lineage. Eosinophilia in the context of ALL is often associated with the presence of eosinophilic precursors in the bone marrow, which is consistent with the findings in this patient. The negative staining for myeloperoxidase and nonspecific esterase rules out a myeloid lineage origin.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the presence of eosinophilia in the context of ALL is a distinct feature, not a rare occurrence. Eosinophilia is observed in approximately 20-30% of ALL cases.

**Option B:** This option is incorrect because the bone marrow examination reveals a cellular marrow with 45% blasts, which is diagnostic of ALL. The presence of eosinophilic precursors further supports the diagnosis.

**Option C:** This option is incorrect because the blasts in this patient are negative for myeloperoxidase and nonspecific esterase, ruling out a myeloid lineage origin. The expression of B-cell markers confirms a B-cell lineage ALL.

**Option D:** This option is incorrect because the patient's presentation and bone marrow examination are consistent with a diagnosis of B-cell ALL with eosinophilia.

**Clinical Pearl / High-Yield Fact**
ALL is the most common type of acute leukemia in children, and eosinophilia is a distinct feature in approximately 20-30% of cases. The presence of eosinophilic precursors in the bone marrow is a characteristic finding in these patients.

**Correct Answer: D. The patient's presentation and bone marrow examination are consistent with a diagnosis of B-cell ALL with eosinophilia.

✓ Correct Answer: D. Inv (16) is often detected in the blasts and the eosinophils