Cytogenetics of lymphomas: a brief review of its theoretical and practical significance

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.

The Prognostic Significance of the Serum p53 Protein Concentration in Chinese Patients with Non-Hodgkin Lymphoma

Objective: To investigate the prognostic significance of cytogenetic abnormalities, staging, patient factors, and the serum p53 protein concentration in Chinese non-Hodgkin lymphoma (NHL) patients.

Material and Methods: The study included 43 patients with NHL that were identified between August 2003 and December 2008. Patient clinical characteristics patients were determined based on morphological, immunohistochemical, and cytogenetic analysis, and the serum p53 protein concentration was measured quantitatively.

Results: Following conventional chemotherapy, the complete/partial remission (CR/PR) rate was significantly higher and overall survival (OS) was significantly longer in the patients with early-stage (stage I-II) lymphoma, normal karyotype, and a low serum p53 protein concentration than in those with advanced-stage (stage III-IV) lymphoma, cytogenetic abnormalities, and a high serum p53 protein concentration (≥0.35 U/mL). Bone marrow infiltration was also a predictor of poor response and OS. There weren’t any significant differences in disease remission between the male and female patients, older and younger patients (aged <70 years vs. ≥70 years), or B-cell lymphoma and T-cell lymphoma patients.

Conclusion: Staging is an effective means of assessing the severity of NHL. Cytogenetic examination can provide useful information for diagnosis, staging, and prognostication. The serum p53 protein level may be a potential prognostic marker in patients with NHL.

Conflict of interest:None declared.

Chronic lymphoproliferative disorders at an Indian tertiary cancer centre - the panel sufficiency in the diagnosis of chronic lymphocytic leukaemia

BACKGROUND

Flow cytometry has come to occupy the vanguard of the high through put diagnostic techniques that have been used to differentiate between various chronic lymphoproliferative disorders (CLPD). However, economic considerations have created the need for minimal consensus panels that can yield maximum information at reasonable costs.

AIMS

To collect, analyse and correlate the morphologic, immunophenotypic, and the cytogenetic data from the cases of chronic lymphoproliferative disorders, which were diagnosed at an Indian speciality cancer centre.

METHODS AND MATERIAL

The morphology was recorded after staining the samples with the Leishman or the MGG stains. The lineage assignment was done by using three colour flow cytometry with a primary panel of antibodies. For the cytogenetic studies, the short term culture of the sample cells were arrested by using colcemid and they were G-banded by using trypsin and Giemsa stain. FISH studies were conducted by using a CLL-specific diagnostic kit.

RESULTS AND CONCLUSIONS

A total of 66 cases were evaluated, which had a median age of 64.5 years and a sex ratio of 2.3:1. Of these 66 cases, 40 cases were of CLL and 9 cases were of atypical CLL. 17 cases were classified as CLPD and these included 13 cases of Non-Hodgkin's Lymphoma, two cases of Hairy Cell Leukaemia, one case of Follicular Lymphoma and one case of Prolymphocytic Leukaemia. In immunophenotyping, the lack of expression of CD22 had the highest correlation with a definitive diagnosis of CLL. Cytogenetics demonstrated a classical follicular lymphoma abnormality, t (14; 18) (q32; q21), in one case. A basic minimal panel is sufficient for the routine diagnosis of CLL. However, the stratification of CLPD requires the use of more extensive panels.

Chromosomal abnormalities of 200 Chinese patients with non-Hodgkin's lymphoma in Taiwan: with special reference to T-cell lymphoma

BACKGROUND

The distribution of the histopathological subtypes of non-Hodgkin's lymphoma (NHL) is different among various geographical areas. However, there are few reports concerning cytogenetic findings of NHL, especially T-cell lymphoma, in Asian people.

PATIENTS AND METHODS

We analyzed the chromosomal abnormalities of 200 adult patients with NHL in Taiwan and correlated the non-random aberrations with the histological subtypes.

RESULTS

One hundred and thirty-eight patients (69%) had B-cell lymphoma. The incidence of the t(14;18) in total lymphoma was lower in Taiwan (12%) than in the West (20-30%), but its incidence in follicular lymphoma was comparable between the two areas (17 of 28 patients, 61% versus approximately 50-60%). Sixty-two patients (31%) had T-cell lymphoma, including 11 angiocentric T/natural killer (NK)-cell lymphoma and only two angioimmunoblastic T-cell lymphoma (AILD). The recurrent chromosomal abnormalities in T-cell lymphoma comprised 6q deletion (30%), 11q deletion (20%), 17p deletion (16%), -17 (16%), -Y (14%) and + 8 (11%). Angiocentric T/NK-cell lymphoma had a significantly higher frequency of 1q duplication (P=0.001), 6p duplication (P <0.001) and 11q deletion (P=0.011) than other T-cell lymphoma. The incidences of +3 and +5, two common abnormalities in AILD, were quite low in T-cell lymphoma in Taiwan (4% and 2%, respectively), compared with those in the West (16-32% and approximately 15%, respectively). The 11q deletion, not a common aberration in T-cell lymphoma in western countries, occurred quite frequently in Taiwan.

CONCLUSIONS

The chromosomal aberrations of NHL are quite different among various geographical areas, which may reflect the differences in the distribution of the histological subtypes of lymphoma among various areas.