Cannibalistic Hemophagocytosis in Acute Myeloid Leukemia with Trisomy 9

Excerpt

A 45-year-old male patient was subjective to bone marrow examination for evaluation of 10-day history of increasing fatigue secondary to severe anemia requiring packed red cell transfusion. His complete blood count at the time of admission revealed severe pancytopenia [hemoglobin-77 g/L, mean corpuscular volume-97 fL, total leukocyte count-0.8 × 10⁹/L, and total platelet count-27 × 10⁹/L, reticulocyte count-0.4 × 10⁹/L]. Peripheral smear examination showed macrocytic normochromic red cells, 3% myeloid blasts with sparse, fine granules, no Auer rods; severe thrombocytopenia; and no evidence of pseudo Pelger Huet type neutrophils. His serum iron profile, vitamin B₁₂, and folate levels were within normal reference range. Bone marrow aspiration from right posterior iliac crest revealed hypercellularity with infiltration by 75% myeloid blasts suppressing trilineage haematopoiesis. These blasts showed abundant pale basophilic finely vacuolated cytoplasm, few with sparse marginated granules and short slender Auer rod, few showing cytoplasmic blebs and pseudopod like extensions; round nuclei, fine chromatin and conspicuous nucleoli. Maturing myeloid elements constituted 10% of marrow nucleated cells. Ten percent of blasts had evidence of hemophagocytic activity of RBCs, platelets, and myeloid cells. Besides these, 3% of these blasts also showed engulfment of another blasts (cannibalism) (Fig. 1a–c). Flow cytometry immunophenotyping of the marrow aspirate using BD FACS Canto II flow cytometer (Becton–Dickinson, San Jose, CA, USA) revealed the following blast profile: SSC^low/CD45^+/dim, CD34^+/bright, HLADR^+/bright, CD13^+/moderate, CD33^+/bright, CD117^+/bright, and aberrant CD7^+/bright; but negative for cMPO, CD 14, CD 64, cCD 79a, CD 19, and cCD 3; consistent with a diagnosis of MPO negative acute myeloid leukemia (AML) (Fig. 2). Bone marrow trephine biopsy showed the infiltration by diffuse sheets of CD34⁺/CD117⁺/MPO⁻/CD31⁺/Glycophorin⁻/CD61⁻ myeloid blasts with evidence of hemophagocytosis and increased reticulin fibrosis (WHO grade 2). Conventional G-banding cytogenetics from the marrow aspirate sample revealed trisomy 9 as the sole abnormality in 9 of 20 analyzed metaphases (47, XY, + 9 [5]/46, XY [15]) (Fig. 3). His molecular work up did not show any abnormality; and his serum ferritin and fasting triglyceride levels were within normal limits. The patient refused induction chemotherapy; and subsequently lost to follow-up. The next of the kin of the patient gave verbal informed consent to write up the case.

…