Morphological studies of pathologicals specimens. (A) Imprint of the three cases of NK-NHL. Case no. 1: Large blastic lymphoid cells looked like immunoblasts with a high mitotic rate (MGG, original magnification × 3,300). Case no. 2: Medium lymphoid cells with irregular nuclei and fine chromatin (MGG, original magnification × 3,300). Case no. 3: Medium and large lymphoid cells with vacuoles and azurophilic granules in the cytoplasm (MGG, original magnification × 3,300). (B) Immunophenotypic analysis. Coexpression study of CD3 and CD56 in the three cases found the unique tumoral phenotype CD3⁻ CD56⁺. Heterogeneity is described concerning CD4 and CD8 expression. Case no. 1: CD4⁻CD8⁺; Case no. 2: CD4⁺CD8⁻; Case no. 3: CD4⁻CD8⁻.