[1414] γ-Synuclein Is a Promising New Marker for Staining Reactive Follicular Dendritic Cells, Kaposi Sarcoma and Follicular Dendritic Cell Sarcoma.

Hailing Zhang, Robert Maitta, Joseph Albanese, Wa Shen, Howard Ratech. Albert Einstein College of Medicine, Bronx; Montefiore Medical Center, Bronx

Background: Synucleins are small soluble proteins found in normal brain and in diverse pathologic conditions. For example, α-synuclein comprises a major component of the Lewy body of neurodegernerative diseases and γ-synuclein has been implicated in aggressive carcinomas with a metastatic phenotype. The role of γ-synuclein has not yet been investigated in the hematopoietic system.
Design: We studied the protein expression of γ-synuclein by immunohistochemical staining of paraffin-embedded, formalin-fixed tissue sections from reactive tonsil (5), lymph node (7), spleen (5), thymus (5) and from neoplastic hematopoietic tumors, including B-cell non-Hodgkin lymphoma (NHL; 45), T-cell NHL (10), classic Hodgkin lymphoma (HL; 10), nodular lymphocyte-predominant HL (3), acute lymphoblastic lymphoma (7), acute myeloid leukemia (12), myelodysplastic syndrome (3), myeloproliferative neoplasm (3). In addition, we studied Kaposi sarcoma (KS; 3) and follicular dendritic cell (FDC) sarcoma (3).
Results: In reactive tissues, γ-synuclein strongly stained follicular dendritic cells as well as vascular and lymphatic endothelial cells. Also, γ-synuclein was strongly expressed in the mucosal epithelium of tonsil and in the Hassall's corpuscles (HC) of thymus. In contrast to CD21, which only stains the arms of the FDCs, γ-synuclein stained both the long slender cellular processes and the cell body, allowing one to clearly visualize the number of individual FDCs. Because γ-synuclein was expressed both in FDCs as well as in vascular and lymphatic endothelial cells, we stained related neoplasms. In 3/3 KS and 3/3 FDC sarcoma, γ-synuclein was strongly expressed in the spindle-shaped tumor cells. We did not detect γ-synuclein in the neoplastic cells of any hematopoietic neoplasm.
Conclusions: To our knowledge, this is the first report that γ-synuclein is strongly expressed in the reactive FDCs of lymph node, tonsil, spleen, and HC of thymus as well as in the neoplastic spindle cells of KS and FDC sarcoma. These results suggest that γ-synuclein may be a promising new adjunct marker for identifying reactive FDCs and for the diagnosis of KS and FDC sarcoma. Studies are currently underway to evaluate the sensitivity and specificity of γ-synuclein expression in a comprehensive panel of other spindle cell neoplasms.
Category: Hematopathology

Tuesday, March 1, 2011 11:00 AM

Platform Session: Section B, Tuesday Morning

 

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