[1512] The Clonal Myeloid Disorder Associated with Isolated del(20q) Is Frequently Subtle, Unclassifiable and May Be Associated with Prior Cytotoxic Chemotherapy

Charanjeet Singh, Michelle Dolan, Michael Berger, Timothy Singleton, Kaveh Naemi, Robert W McKenna. University of Minnesota, Minneapolis, MN

Background: Isolated del (20q) bone marrow (BM) chromosome abnormality is not considered definitive evidence of myeloid neoplasm in the absence of supporting morphologic abnormalities (WHO-2008). The purpose of this study is to identify the spectrum and recurring features of myeloid disorders with isolated del(20q).
Design: In the interval between the years 2002-2012, karyotyping identifed 50 cases of BM chromosome del(20q) in our institution. BM biopsies from these cases were reviewed. Data analyzed included patient demographics, CBCs, blood & BM blast counts, degree & nature of dysplasia, and morphologic diagnosis.
Results: 42 of the 50 cases had del(20q) as sole cytogenetic abnormality. Eight cases (6 myelomas, 2 MDS) had complex coexistent cytogenetic abnormalities & were excluded from further analysis. 20 of the 42 patients with isolated del(20q), (48%; mean age= 64.5y, range 35-84y; M:F=3:1) had a classifiable myeloid neoplasm; 4 with primary myelofibrosis & a JAK2 mutation and 16 with MDS (RCMD or RAEB). The remaining 22 patients (52%; mean age=63.4y, range=31-83y; M:F=2.6:1) had BM exams to evaluate for cytopenias, red cell macrocytosis or a non-myeloid neoplasm. 16 of these (38%) had subtle morphologic abnormalities in various myeloid lineages but insufficient to definitively classify them into a category of MDS, and were considered MDS-unclassifiable (MDS-U), 1 patient had a MPN-unclassifiable and in 5 (12% of patients) the BM was normal. The 16 patients with MDS-U had slight macrocytosis and/or slight cytopenias but less than 10% dysplastic cells in any lineage. Occasional hypogranular neutrophils, hypolobate megakaryocytes and/or terminal dyserythropoiesis were present in most but none of these cases showed significant nuclear dysplasia in granulocytic or erythroid lineages or increased myeloblasts or ring sideroblasts. 5/20 cases with a classifiable myeloid neoplasm and 8/22 with unclassifiable disease had received prior cytotoxic chemotherapy for a non-myeloid neoplasm.
Conclusions: In this study isolated del(20q) was associated with a definable myeloid neoplasm in <50% cases. In a majority, 22/42 (52%), isolated del(20q) was found in the absence of morphologic abnormalities sufficient for the diagnosis of a specific category of MDS. Isolated del(20q) is not presently considered a recurrent abnormality in therapy related myeloid neoplasms but may be a component of a complex karyotype. In this study 13/42 patients (31%) with isolated del(20q) had received prior cytotoxic chemotherapy.
Category: Hematopathology

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 233, Monday Morning

 

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