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Case Reports in Pathology
Volume 2015, Article ID 594970, 4 pages
Case Report

Extramedullary Hematopoiesis in a Sentinel Lymph Node as an Early Sign of Chronic Myelomonocytic Leukemia

1Physicians Laboratory, 4840 F Street, Omaha, NE 68117, USA
2Department of Pathology, University of Manitoba, MS559S Thorlakson Building, 820 Sherbrook Street, Winnipeg, MB, Canada R3A 1R9
3Department of Pathology and Microbiology, University of Nebraska Medical Center, 985900 Nebraska Medical Center, Omaha, NE 68198, USA
4Jane Anne Nohl Division of Hematology and Center for the Study of Blood Diseases, University of Southern California (USC) and Norris Cancer Center, USC University Hospital, 1441 Eastlake Avenue, Norris Topping Tower 3463, MC 9172, Los Angeles, CA 90033-9172, USA

Received 26 February 2015; Revised 27 March 2015; Accepted 3 April 2015

Academic Editor: Sami Shousha

Copyright © 2015 Joslin M. Bowen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic malignancy with features of both a myeloproliferative neoplasm and a myelodysplastic syndrome. Even though extramedullary leukemic infiltration is common in CMML patients, lymph node involvement has rarely been reported in the literature. We present an unusual case of a 72-year-old female who was found to have extramedullary hematopoiesis (EMH) in a sentinel lymph node that was excised during mastectomy for lobular breast carcinoma. One year later bone marrow biopsy was performed due to persistent anemia, thrombocytopenia, and monocytosis and the patient was diagnosed with CMML. Our case illustrates the importance of recognizing EMH in a lymph node during routine histological examination, especially in adults. Proliferation of bone marrow elements in a lymph node, in a patient with no known hematologic disorder, should trigger immediate bone marrow evaluation, as this could be the first clue in diagnosing underlying bone marrow disorder.