Q. I was reading your post about hypereosinophilic syndrome – can you please explain why the other answers are incorrect?

A. Sure! For those of you who didn’t see the previous post, here’s the question:

A 62-year-old male presents with hepatosplenomegaly, skin lesions, and cardiomyopathy. A representative field of his blood smear is shown here. Of the following, which is the most likely diagnosis?

A. Multiple myeloma
B. Chronic myeloid leukemia
C. Metastatic prostate carcinoma
D. Hypereosinophilic syndrome
E. Bacterial sepsis

The answer is D, hypereosinophilic syndrome (check out the original post for a discussion of this diagnosis). Let’s look at the reasons the other answers are wrong.

A. In a blood smear from a patient with myeloma, the main thing you see is rouleaux (red cell stacking up on top of each other). You generally don’t see plasma cells in the blood – but you do see them in the marrow. This blood smear just has a lot of eosinophils – so it’s not consistent at all with myeloma. The clinical history also doesn’t fit. In myeloma patients usually have bone pain, signs of anemia (fatigue, palpitations), and maybe signs of renal failure. Hepatosplenomegaly, skin lesions, and cardiomyopathy aren’t generally seen in myeloma.

B. In CML (check out the photo above), you see a massive leukocytosis which is composed of neutrophils and precursors. There is a big left shift, with “bulges” (more cells) at the myelocyte and segmented neutrophil stages. Most cases also show a distinct basophilia. This smear just has a ton of eosinophils, which is not a finding you see in CML. The patient’s hepatosplenomegaly would be consistent with CML (especially the splenomegaly part) – but the skin lesions and cardiomyopathy don’t go along with that diagnosis.

C. In metastatic prostate cancer, it’s possible that you might see a rare tumor cell in the blood; you might also see a monocytosis (you occasionally can see that with solid tumors). Eosinophilia is not consistent with prostate cancer. The history, too, doesn’t fit. Patients with prostate cancer often have urinary symptoms (trouble urinating, blood in the urine), and some have signs of metastasis (bone pain, particularly in the spine).

D. The characteristic blood finding in bacterial sepsis is a neutrophilia, with or without a left shift. You may also see toxic changes in the neutrophils: toxic granulation, Dohle bodies, and/or cytoplasmic vacuolization. Bacterial infections generally don’t produce an eosinophilia – but some parasitic infections can.