Usefulness of routine conventional cytogenetic analysis in tissues submitted for "lymphoma work-up"

Non-Hodgkin lymphomas (NHLs) are often characterized by specific cytogenetic abnormalities. We evaluate the utility of routine cytogenetic studies in 261 "lymphoma work-ups". These include 4 non-hematolymphoid malignancies and 257 hematolymphoid processes submitted over 3 years, including even those initially appearing benign by morphology and immunophenotyping. About 64/257 yielded no results and 5/78 "lymphoid hyperplasia/lymphadenitis" were abnormal; 3 of these 5 appeared clonal [1, shortly followed by follicular lymphoma (FL)]. Increasing FL grades showed decreased t(14;18)/increased del 6q abnormalities. 1/4 Burkitt lymphomas (BL) (i.e., an atypical BL) showed t(8;14) and t(14;18) (i.e., a double-hit). 1/4 post-transplant lymphoproliferative disorders (PTLD) showed abnormalities, confirming clonality. One "extramedullary hematopoiesis" with a previous myelodysplastic syndrome and 1 erythroblastic sarcoma showed abnormalities, confirming myelodysplasias (MDS). A monocytic sarcoma revealed a t(9;11)(p22;q23). Routine cytogenetic studies aid in "lymphoma work-ups" by (1) detecting rare abnormalities in cases without apparent malignancy, indicating close follow-up, (2) detecting abnormalities in FL correlating with increasing grade, (3) detecting co-existent t(8;14) and t(14;18) in BL, indicating a worst prognosis, (4) establishing clonality in PTLD and (5) establishing diagnoses of MDS or chloroma in tissues. The findings by the conventional karyotyping studies in many of these cases added significant data to the diagnostic cases, beyond morphologic and immunophenotypic findings, and were not amenable to directed fluorescent-in-situ hybridization studies.