Fine needle aspiration of lymphoblastic lymphoma: A multiparameter diagnostic approach

Sixteen fine needle aspiration (FNA) biopsies of lymphoblastic lymphoma (LBL) that were used to either initially diagnose disease (12) or document relapse (4) were reviewed. Cellular aspirates (2 x 10⁷ cells) were readily obtained for immunologic, DNA/RNA flow cytometric and immunoglobulin and/or T-cell receptor gene rearrangement studies. Cytologically, aspirates were characterized by intermediate-sized cells (9.5-18.5 μm) with fine nuclear chromatin, small, inconspicuous nucleoli, irregular nuclear contours and scant basophilic cytoplasm. Frequent mitotic figures were seen (1-14 figures per 1,000 cells). Fourteen cases demonstrated a T-cell phenotype with considerable phenotypic variability. One case demonstrated a precursor B- cell phenotype, and another demonstrated biphenotypic expression with both T- cell and myeloid differentiation. Eleven of 14 cases (79%) were positive for terminal deoxynucleotidyl transferase. Thirteen of 15 cases (87%) manifested diploid DNA content by flow cytometric analysis and were characterized by intermediate proliferative activity (S + G₂M 12.7 ± 8.7% SD) and intermediate mean RNA index (1.3 ± .5 SD). Tβ gene rearrangements were demonstrated in four of five phenotypic T-cell LBL cases analyzed, with concomitant J(H) gene rearrangements observed in three cases, confirming that bigenotypic rearrangements characterize some T-cell LBLs. We conclude that FNA samples are adequate for accurate characterization of LBL and may obviate the need for surgical biopsy.