To the Editor: The inversion of chromosome 16, inv(16), a cytogenetic abnormality expressed in core binding factor acute myeloid leukemias (AML), is associated with myelomonocytic differentiation and eosinophilia.¹ Even though inv(16) generally portends a good prognosis, accompanying mutations detected by molecular genetic methods, such as KIT and Ras mutations, alter their response to treatment.² Infiltration of leukemic cells into serous effusions is unusual. To our knowledge, there are only a few reports of AML with inv(16) presenting with leukemic ascites.² 

We present a 33-year-old woman with jaundice and massive ascites. The laboratory tests showed the following: hemoglobin 8.3 g/dL, hematocrit 25%, total leukocyte count 135800/mm³, and platelet count 32000/mm³, erythrocyte sedimentation rate 45 mm/hr, AST 597 U/L, ALT 111 U/L, ALP 417 U/L, GGT 191 U/L, lactate dehydrogenase 6515 U/L, total bilirubin 9 mg/dL and direct bilirubin 8.2 mg/dL. On peripheral blood smear, myeloblasts comprised 67% of the cells and the bone marrow analysis showed 57% myeloblasts with eosinophilic differentiation. Immunophenotypic analysis of the bone marrow was positive for CD13, CD14, CD45, CD33, CD34 and HLA-DR. FISH analy.sis of the bone marrow revealed an inv(16) signal. The final diagnosis was acute myelomonocytic leukemia (FAB Classification M4e) with inv(16). Abdominal computed tomography revealed massive ascites and multiple lympadenopathies with a maximal diameter of 1.5 cm at the mesenteric region. A diagnostic and therapeutic paracentesis was performed. Analysis of the ascitic fluid showed an exudate with a white blood cell count 3140 cells/ mL; red blood cell count 70000 cells/mL; monocyte count 1910 cells/mL. The ascitic total protein was 3.9 g/dL (serum, 7.1 g/dL), glu.cose 208 mg/dL (serum, 216 mg/ dL), lactate dehydrogenase 1918 U/L (serum, 2813 U/L) and albumin 2.4 g/dL (serum, 3.9 g/dL). Cytocentrifuge preparation of the patient’s ascitic fluid showed myelo.blasts and monoblasts with irregular nuclei and prominent nucleoli (Figure 1). Flow cytometric analysis of the ascitic fluid showed the expression of CD13, CD14, CD33, CD34, CD45 and HLA-DR compatible with the diagnosis of acute myeloid leukemia-M4 (AML-M4) (Figure 2). The patient was treated with cytarabine 100 mg/m2 for 7 days and idarubucin 12mg/m2 for 3 days. On the third day of the remis.sion induction therapy, ascites dis.appeared and the liver enzymes and bilirubin levels returned to normal on completion of the first week of therapy. The patient was under follow up at our hematology depart.ment at the time of writing. 

Leukemic infiltration of effusions have been mostly reported in AML with monocytic differentiation, including M4 and M5 AML in the FAB classification.^3,4 Yet, development of leukemic ascites at initial presentation of AML, as in our case, is a rare entity.⁵ Also, in few previous cases, leukemic ascites has been reported as the present.ing feature in inv(16) AML.² Our case emphasizes the importance of performing paracentesis and an extensive diagnostic work-up in AML presenting with ascites to differenti.ate leukemic infiltration from other causes. Further studies are needed to to identify the clinical significance of inv(16) in the presence of leukemic ascites. 

References

1. Le Beau MM, Larson RA, Bitter MA, Vardiman JW, Golomb HM, Rowley JD. Association of an inversion of chromosome 16 with abnormal marrow eosinophils in acute myelomonocytic leukemia. A unique cytogenetic-clinicopathological associa.tion. N Engl J Med. 1983 Sep 15;309(11):630-6.

2. Fujieda A, Nishii K, Tamaru T, Otsuki S, Kobayas.hi K, Monma F, et al. Granulocytic sarcoma of mesentery in acute myeloid leukemia with CBFB/ MYH11 fusion gene but not inv(16) chromosome: case report and review of literature. Leuk Res. 2006 Aug;30(8):1053-7.

3. Simel DL, Weinberg JB. Leukemic ascites complicating acute myelomonoblastic leukemia. Arch Pathol Lab Med. 1985 Apr;109(4):365-7.

4. Domingo-Domènech E, Boqué C, Narváez JA, Romagosa V, Domingo-Clarós A, Grañena A. Acute monocytic leukemia in the adult presenting with associated extramedullary gastric infiltration and ascites. Haematologica. 2000 Aug;85(8):875-7.

5. Koc Y, Miller KB, Schenkein DP, Daoust P, Sprague K, Berkman E. Extramedullary tumors of myeloid blasts in adults as a pattern of relapse fol.lowing allogeneic bone marrow transplantation. Cancer. 1999 Feb 1;85(3):608-15.