A diagnosis of myeloid sarcoma (granulocytic sarcoma or chloroma) usually refers to a tumor arising from the extramedullary infiltration of leukemic cells that (1) precedes or occurs concurrently with acute myelogenous leukemia (AML) of the bone marrow, or (2) heralds the blastic transformation of a chronic myeloproliferative disorder. The infiltration of leukemic cells into serous effusions is unusual. Extramedullary infiltration of effusions has been reported most often in cases of AML with monocytic differentiation, including M4 and M5 AML in the French American British classification.1,2 We present a case of leukemic ascites that illustrates how unexpected extramedullary sites of relapse in AML, such as the paranasal sinuses, female genital tract, and breast, are being recognized with increasing frequency as the long-term survival of leukemic patients improves.3
A 27-year-old man diagnosed with acute myelomonocytic leukemia (M4 AML) underwent induction chemotherapy followed by a female sibling matched allogeneic stem cell transplant. His karyotype at this time was 46,XY, - 18, + mar. Almost 2 years after his transplant he presented with an occipital subcutaneous myeloid sarcoma. Although immunohistochemical studies were not performed on this scalp mass, cytogenetic studies showed more complex abnormalities including t(2;7;7;5) and t(6; 16). A bone marrow biopsy did not reveal recurrent acute myelomonocytic leukemia (M4 AML) and yielded a 46,XX karyotype consistent with successful engraftment. His mass was successfully treated with local radiation therapy. One month later he presented with dyspnea, weight gain, abdominal distention, and pedal as well as scrotal edema. On examination, he had tense ascites with prominent shifting dullness. His peripheral white blood cell count was 9200/µL with 90% neutrophils and no circulating blasts. A chest x-ray film revealed bilateral pleural effusions. Axial postoral contrast computerized tomographic scans obtained through the upper abdomen (Figure 1) and pelvis demonstrated a large amount of ascitic fluid (indicated by stars) throughout the peritoneal cavity. Apart from some peripancreatic lymphadenopathy, there was no thickening of the peritoneal lining, and no masses or peritoneal implants were present. There was no evidence of another site of solid tissue involvement.
A diagnostic and therapeutic paracentesis was performed. Analysis of the patient's ascitic fluid showed an exudate with a white blood cell count of 288 cells/µL; red blood cell count of 72 cells/µL; total protein of 1.3 g/dL; glucose, 99 mg/dL (serum, 107 mg/dL); lactate dehydrogenase, 168 U/L (serum, 609 U/L); and albumin, 0.7 g/dL (serum, 3.5 g/dL). Cytologic examination of Wrightstained cytocentrifuged preparations showed a markedly cellular fluid (Figure 2) composed of immature granulocyte precursors including 85% myeloblasts. The blasts had a high nuclear to cytoplasmic ratio, with immature and folded nuclei containing fine granular chromatin and prominent nucleoli (Figure 3). They also had a deeply basophilic cytoplasm with numerous small vacuoles and were strongly myeloperoxidase positive. Coarse and sparse cytoplasmic granules were clearly evident in some of the differentiating immature myelocytes. Auer rods were not seen. Mitotic figures were abundant. Megakaryocytes and erythroid precursors were not apparent, and no microorganisms were identified. Flow-cytometric analysis of the ascitic fluid demonstrated that the majority of the cells (82% of total gated events) expressed CD34 and HLA-DR; myeloid-associated antigens CD13, CD33, CD117, CD11c, and CD15; as well as a subset that coexpressed monocytic markers CD14 and CD64. These findings are diagnostic of acute myelomonocytic leukemia (M4 AML). Cytogenetic studies were not performed on the ascites. The patient died within 1 month of his presentation with ascites.
The development of leukemic ascites at initial presentation and also as a late extramedullary relapse following bone marrow transplantation for AML, of monocytic differentiation as well as other subtypes, is rare.3 Infectious peritonitis in such cases needs to be excluded. The finding of large immature neoplastic cells in ascitic fluid can be seen with large cell lymphoma, natural killer cell lymphoma, poorly differentiated carcinoma, sarcoma, and melanoma. Cytochemistry to demonstrate peroxidase-positive leukemic cells and diagnostic immunohistochemical studies may help. If available, flow cytometry and cytogenetics can be used to further classify AML, particularly in cases such as this one, where the bone marrow did not reveal evidence of disease.
1. Simel DL, Weinberg JB. Leukemic ascites complicating acute myelomonoblastic leukemia. Arch Pathol Lab Med. 1985;109:365-367.
2. Domingo-Domenech E, Boque C, Narvaez JA, Romagosa V, Domingo-Claros A, Granena A. Acute monocytic leukemia in the adult presenting with associated extramedullary gastric infiltration and ascites. Haematologica. 2000;85:875-877.
3. Koc Y, Miller KB, Schenkein DP, Daoust P, Sprague K, Berkman E. Extramedullary tumors of myeloid blasts in adults as a pattern of relapse following allogeneic bone marrow transplantation. Cancer. 1999;85:608-615.
Liron Pantanowitz, MD; Richard Steingart, MD; Kenneth B. Miller, MD; Jonathan B. Kruskal, MD; German Pihan, MD
Accepted for publication August 27, 2004.
From the Departments of Pathology (Drs Pantanowitz and Pihan), Medicine (Hematology-Oncology Division) (Dr Miller), and Radiology (Dr Kruskal), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass; and the Departments of Pathology (Dr Pantanowitz) and Medicine (Hematology-Oncology Division) (Dr Steingart), Baystate Medical Center, Tufts Medical School, Springfield, Mass.
The authors have no relevant financial interest in the products or companies described in this article.
Reprints: Liron Pantanowitz, MD, Baystate Medical Center, Department of Pathology, 759 Chestnut St, Springfield, MA 01199 (e-mail: firstname.lastname@example.org).
Copyright College of American Pathologists Feb 2005
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