1. Patient history 70 year-old male with macrocytic anemia for 10 years, became transfusion dependent. Splenectomy for refractory anemia: 670gm B12, folate, thyroid function: unremarkable Two prior BM biopsies: hypercellular with no specific diagnosis; normal cytogenetics

2. Peripheral blood WBC 5.6 x10 9 /L HGB 8.0 g/dL MCV106 fL Plt 485 x10 9 /L Neutrophil 65.0% Lymphocyte 20.0% Monocyte 14.5% Basophil 0.5% Abs. lymphocyte: 1.1 x 10 9 /L

3. Bone marrow aspirate

4. H&E CD3 Bone marrow core biopsy

5. Example case 2 H&E CD3 Intrasinusoidal infiltration (single-cell layer)

6. CD3   CD3 CD7 CD5 CD3 CD4 CD2 CD8 CD4-CD8-  T cells Normal  T cells Flow cytometry Immunophenotype summary: CD3+, CD4-/CD8-, TCR  +, CD2+, CD5-, CD7+ TIA-1+, partial granzyme B+ CD158 a-/b+/e- CD56-, CD16-, CD57-

7. TIA-1 CD3 Spleen

8. Molecular analysis: Identical clonal TCR gene rearrangement in peripheral blood & spleen samples Cytogenetic studies: 46, XY FISH for i(7q): Negative