[1476] The Genetics of Interdigitating Dendritic Cell Tumors Shares Some Changes with Langerhans Cell Histiocytosis in Select Cases

Dennis P O'Malley, Lawrence Zuckerberg, Lauren Smith, Todd S Barry, Shelley Gunn, Wayne Tam, Attilio Orazi, Young S Kim, Lawrence Weiss. Clarient Inc./GE Healthcare, Aliso Viejo, CA; Massachusetts General Hospital, Boston, MA; University of Michigan, Ann Arbor, MI; Spectrum Pathology, Mission Viejo, CA; PathCentral, Irvine, CA; Weill-Cornell Medical Center, New York, NY; City of Hope National Medical Center, Duarte, CA

Background: Histiocytic disorders have been noted to have evidence of transdifferentiation; examples of cases with combinations of different lineages have been shown. In our index case, we identified interdigitating dendritic cell (IDC) differentiation in a case of Langerhans cell histiocytosis (LCH). Little is currently known about the genetics of IDC tumors (IDCT), as they are exceedingly rare. Using array comparative genomic hybridization (aCGH), we evaluated 4 cases of IDCT, and compared them to our index case, as well as other published genetic abnormalities of Langerhans cell histiocytosis.
Design: 4 cases of paraffin embedded samples of IDCT and one case of LCH with IDC differentiation were evaluated using aCGH.
Results: aCGH results showed no abnormalities in the index case. In 3/4 cases of IDCT, genetic abnormalities were identified; one case had no identifiable abnormalities. IDCT case 1 had gains of 3q and 13q. IDCT case 2 had trisomy 12. IDCT case 3 had deletions of 7p, 12p, 16p, 18q, 19q, and 22q. IDCT case 4 had no detectable abnormalities.
Conclusions: Our index case, LCH with IDC differentiation, showed no abnormalities by aCGH. A number of LCH cases do not have detectable genetic abnormalities, suggesting some cases may be non-neoplastic. In contrast, 3/4 cases of IDCT evaluated had identifiable abnormalities by aCGH. Further, two of these shared abnormalities, albeit of large genetic regions, with published abnormalities seen in LCH. No recurrent abnormalities were identified in the IDCT cases. However, the possibility of a relationship between IDCT and LCH cannot be entirely excluded by these results.
Category: Hematopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 269, Tuesday Afternoon


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