Evaluation of Lymphoid Cell Populations in Cytology Specimens Using Flow Cytometry and Polymerase Chain Reaction

Abstract

Differential diagnosis between lymphomas and reactive lymphoid proliferations often requires ancillary techniques and morphologic evaluation. Flow cytometry (FCM) and polymerase chain reaction (PCR) can aid the detection of monoclonal B-cell populations. In the present study, the sensitivity and specificity of these two methods in the study of cytology specimens were compared. Eighty-six cytologic specimens from 81 patients (lymph nodes, solid organs, and body cavities) were evaluated. These specimens were taken from three groups of patients: those who underwent an initial evaluation for suspected lymphoma; those who were previously diagnosed with B-cell lymphoma and were now evaluated for possible disease recurrence; and those who were diagnosed with a nonhematologic malignancy. Histologic diagnosis was available for 51 samples. All samples were tested by FCM for the detection of monoclonality using kappa:lambda ratio and for clonal immunoglobulin heavy chain (IgH) gene rearrangements using a single-round PCR after cytologic evaluation. Tissue morphology, FCM and PCR results, and clinical findings in specimens without histologic diagnosis were correlated. Histologic evaluation (N = 51) revealed 44 specimens with B-cell malignancy. Twenty of the 44 lymphoma specimens (45%) were accurately diagnosed in cytologic smears, 18 (41%) were classified as suspicious of lymphoma, and 6 (14%) were diagnosed as reactive. FCM had superior sensitivity compared with PCR (77% vs. 64%). Fifty-six percent of specimens with B-cell malignancy were FCM+/PCR+, 23% were FCM+/PCR-, 14% were FCM-/PCR+, and 7% were FCM-/PCR-. The combined use of FCM and PCR resulted in a diagnosis of B-cell lymphoma in 41 (93%) of 44 B-cell lymphoma specimens and increased the sensitivity of fine needle aspiration by 48%. Both FCM and PCR aid in the diagnosis of lymphoid lesions in cytology specimens, and both can detect monoclonal B-cell populations that may be interpreted in cytology smears as reactive, even by experienced cytologists. Although FCM had higher sensitivity than PCR test in the present study, their combined use should be considered because of a relatively large number of specimens that were detected as monoclonal only with PCR.

Adult T-cell leukemia/lymphoma

“…This has been evidenced by studies showing that nonHodgkin lymphomas can be accurately diagnosed in cytologic specimens utilizing ancillary techniques such as immunocytochemistry and flow cytometry. 4,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] In the REAL classification, ATLL belongs to the category of peripheral T-cell and natural killer cell neoplasms. Although several reports of peripheral Tcell lymphoma have been published in the cytology literature, [33][34][35][36][37] we are aware of only a single cytologic study of T-cell lymphoma in HTLV-1 positive patients.…”

Flow cytometric characterization of cerebrospinal fluid cells

“…Normal ranges for the LCR differ between laboratories. A LCR threshold of two was reported to have a specificity of 92.3% and a sensitivity of 73.1% (98), while other studies proposed thresholds ranging from 2 to 6, with highest specificities and sensitivities around 70% (99)(100)(101)(102)(103)(104). This indicates that if, for example, a threshold of two is used, $10% of patients with a LCR above 2 are reported to have a monoclonal B-cell population, but do not have a B-cell lymphoma.…”

Lymph Node Fine-Needle Cytology: Beyond Flow Cytometry

“…In particular, IGH/TCR PCR can confirm FNC/FC diagnoses of lymphoma or assess polyclonality, adding clinical value to the FNC diagnoses of nodal and extranodal processes [40,54]. Mayall et al [55] maintain that, because of its high efficiency and short turnaround time, IGH/TCR PCR may replace FC on FNC samples, whereas Davidson et al [56] suggested that their combined use should be advisable because of a relatively high rate of monoclonality detection by PCR only. Maroto et al [4] stressed that IGH/TCR PCR enhances the LN FNC and FC diagnosis and cautioned on the risk of false positives and negatives by using a single primer pair PCR amplification over seminested methods.…”