A 37 year old woman developed axillary lymphadenopathy and a rash over a two week period after a trip to South America. The lymph node biopsy shows florid follicular hyperplasia. There is focal mild expansion of the paracortex, with a predominance of small mature lymphocytes and small foci of larger lymphoid cells. Immunophenotyping by flow cytometry demonstrates that all of the T-cells in the lymph node express CD2, CD3, CD5, CD45 and the T-cell receptor alpha-beta but completely lack CD7. The CD4:CD8 ratio is 6.3:1 on the aberrant T-cells. There is a mixture of CD4+, CD8- and CD4-, CD8+ T-cells. Gene rearrangement studies for the B- and T-cell receptors (beta and gamma chains) were negative. Lack of CD7 was noted with two different monoclonal antibodies from two different companies (Coulter and BD) with two different flourochromes (FITC and PE). The peripheral blood counts were normal. The lymphocytes appear unremarkable, except for rare mildly atypical/reactive forms. Immunophenotyping was performed by flow cytometry on the peripheral blood. Most of the lymphocytes are mature T-cells that, again, completely lack CD7, with a CD4:CD8 ratio of 3.7:1. Has anyone heard of a constitutional or hereditary or congenital lack of CD7? Although I considered a T-cell lymphoma, the morphology looks reactive; the gene rearrangement studies are negative; there are essentially no normal T-cells with expression of CD7; and these aberrant T-cells are a mixture of CD4+, CD8- and CD4-, CD8+ cells. Tim Singleton, MD Flow Cytometry William Beaumont Hospital
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