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

Cytogenetics with flow cytometry in lymph node/extranodal tissue biopsies is sensitive to assist the early diagnosis of suspected lymphomas

Few studies have examined the value of cytogenetic studies with flow cytometry (FC) in lymph node/extranodal tissue biopsies with suspected lymphoma. To evaluate this, G-banded karyotyping and/or fluorescence in situ hybridization (FISH) with FC immunophenotyping were performed on 185 lymph node or extranodal tissue biopsy specimens with suspected lymphoma. Complete cytogenetic analysis of lymph node/extranodal tissue was successful in 174 cases (94.1%) and 57.5% demonstrated chromosomal abnormalities. In 116 malignant lymphoma cases, 83.8% showed abnormalities. In 74 B cell lymphomas (B-NHL), abnormalities were more frequent in lymph node/extranodal tissues than in bone marrow by conventional cytogenetics (CC, 97.2 vs 26.1%), FISH (70.6 vs 17.6%), and FC (98.6 vs 28.4%). Three B-NHL diagnoses were confirmed by re-biopsy of lymph nodes due to the presence of abnormalities in the first biopsy, but no evidence of malignancy in pathological, FC, or IgH/TCR gene rearrangement analyses. In 29 T cell lymphomas (T-NHL), abnormalities were more frequent in lymph nodes than in bone marrow by CC (67.9 vs 21.4%) and FC (75.9 vs 27.6%) analyses. As expected, in 13 Hodgkin lymphoma cases, abnormalities were more frequent in lymph nodes than bone marrow by CC (41.7 vs 16.7%) and FC (30.8 vs 7.7%) analyses. In 56 reactive lymphoid hyperplasias (RLH), 7.1% had conventional clonal cytogenetic abnormalities. Two of these patients died of disease progression and two had their pathological diagnosis revised after the second review. These findings indicate that cytogenetic analysis combined with FC in lymph node/extranodal tissue biopsies can provide critical information in the auxiliary diagnosis of lymphoma.

Clonal cytogenetic abnormalities are predictor in developing non-Hodgkin lymphomas?

Pathological analysis is the cornerstone for diagnosing malignant lymphoma. Status of cytogenetic abnormalities is frequently left unexamined if no evidence of malignancy is found in pathological analysis. In this study, we presented 3 cases in which clonal cytogenetic abnormalities were detected but morphological alterations of the same tissue did not support malignant non Hodgkin lymphoma at the first lymph node biopsy. Case 1 is a 55-year-old female with lymphadenopathy neoplastic process confirmed by flow cytometry and polymerase chain reaction (PCR). Chromosome analysis revealed 47,XX,t(3;22)(q27;q11),+del(9)(p12)[16]/46,XX[4]. The pathological analysis of subsequent lymph node biopsy indicated diffuse large B-cell lymphoma (DLBCL). Case 2, a 74-year-old female, for whom the pathological analysis, molecular studies and flow cytometric analysis of the first lymph node biopsy found no evidence of clonal cell. Cytogenetic analysis demonstrated a terminal deletion of chromosome 7 and 1, and the patient received a second lymph node biopsy and splenectomy. A pathological diagnosis of splenic marginal zone lymphoma (SMZL) was made. In Case 3 who was a 66-year-old female with right cervical and axillary lymph node enlargement. Cytogenetic analysis showed clonal karyotypic abnormalities: 48,XX, t(14;18)(q32;q21) [13]/46, XY [7]. The diagnosis of follicular lymphoma was rendered by the second biopsy of axillary lymph node according to the analysis of morphology and immunohistochemistry. We propose that clonal cytogenetic abnormalities may be a high potential risk for developing non-Hodgkin lymphomas. Follow-up and rebiopsy must be performed in patients who are cytogenetically abnormal but morphologically benign.