[1326] Expression of Thymidine Phosphorylase in Lymph Nodes with Mycosis Fungoides Involvement.

Xingcao Nie, Rekha Bhat, Essel Dulaimi Al-Saleem, Eric Vonderheid, J Steve Hou. Drexel University College of Medicine, Philadelphia, PA; Johns Hopkins Medical Institutes, Baltimore, MD

Background: Thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor, has been known to be over-expressed in both tumor cells and tumor stromal cells in variety of cancers. TP is thought to be involved in tumor growth and metastasis via its anti-apoptotic and pro-angiogenic features. To date, there have been few studies in hematopoietic malignancies. The current study explores TP expression in lymph nodes involved with Mycosis Fungoides (MF).
Design: Archived paraffin blocks with lymph nodes from 51 patients with MF (1991-2010) were used to construct a tissue microarray. 51 MF patients had either a diagnosis of dermatopathic lymphadenopathy (DL: 34/51) or lymph nodes involved by MF (MF-LN: 17/51). Immunohistochemical (IHC) staining using antibodies to TP, CD68, CD21, CD3 and CD4 were performed.
Results: TP immunostaining was noted in subsets of intermediate to large neoplastic T lymphocytes with a characteristic intense cytoplasmic and nuclear staining pattern in all MF-LN cases. Small lymphocytes were negative for TP. In addition, TP staining was also noted in macrophages, dendritic cells and endothelial lining cells. Concurrent CD68 and CD21 staining support the above observations. TP immunostaining was noted in macrophages and follicular dendritic cell meshworks in both DL and benign lymph nodes.
Conclusions: This dataset for the first time demonstrates that TP staining in neoplastic T cells is present in Mycosis Fungoides but not in benign small lymphocytes, in addition to strong staining in macrophages and dendritic cells. This observation may be due to changes intrinsic to the tumor cells itself and/or it may reflect interactions between the tumor microenvironment and the lymphoma cells. The exact mechanism of increased TP expression in lymphoma cells needs further investigation.
Category: Hematopathology

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 229, Tuesday Morning


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