Pitfalls of diagnosis based on abnormal flow cytometry and [(18)F]fluorodeoxyglucose positron emission tomography

Observations on hematogones with light chain restriction

Light-chain restricted hematogones (LCR HGs) detected by flow cytometry (FC) may, occur in bone marrow mimicking involvement by a B-cell lymphoma. This phenomenon can present a diagnostic pitfall and negatively impact patient management, and may occur in other organs, including lymph nodes, For this reason, it is recommended to utilize, in case of LCR in lymph node, one additional morphological, phenotypical or molecular criteria for the diagnosis of lymphoma on cytological samples.

Utilization of Flow Cytometry in Pediatric Fine-Needle Aspiration Biopsy Specimens

BACKGROUND

Fine-needle aspiration (FNA) coupled with flow cytometry (FC) can be helpful in suspicious pediatric lymph nodes or masses to exclude a lymphoproliferative disorder. The aim of this study was to analyze FC findings in a series of pediatric FNAs and to correlate abnormal findings with follow-up information.

MATERIALS AND METHODS

All pediatric FNAs performed at a tertiary-care children's hospital over a 46-month period that had FC performed were retrospectively analyzed and correlated with follow-up.

RESULTS

A total of 163 FNA procedures were performed in children (age ≤21 years), and 47 (28.8%) of these cases had FC performed. Specimens were mostly obtained from the head and neck (72.3% of cases). Nine cases (19.1%) had abnormal FC findings, including double-negative T cells (n = 3; 33.3%), double-positive T cells (n = 3; 33.3%), excess λ light chains (n = 1; 11.1%), weak CD34 positivity (n = 1; 11.1%), and T-lymphoblastic lymphoma (n = 1; 11.1%).

CONCLUSION

Unusual FC results that are not diagnostic of malignancy can be seen in lymph node FNA in a minority of young patients. In our series, these findings were seen mainly in small populations of T cells and occurred primarily in the setting of reactive lymphoid hyperplasia or ectopic thymic tissue. Cytopathologists performing FNA on children should be aware of these abnormalities and, although they may warrant further investigation and follow-up, they are unlikely to be associated with malignancy.

Flow cytometric pattern recognition of lymph node biopsies with lymphomas that lack lineage characteristics

Although immunophenotyping (IPT) using flow cytometry is a routine technique that is applied in many laboratories as a diagnostic tool for lymphadenopathy, some diagnostic challenges persist. In this review, we will discuss pitfalls in the daily practice of lymph node diagnostics with the focus on general characteristics as lymphoid scatter patterns and lineage specific antigens that are used to define lymphoid populations. The absence of these characteristics on proliferating lymphoid cells can potentially lead to a wrong diagnosis. At the same time, this provides evidence for malignant transformation. Sporadic examples of reactive lymphoid proliferations with similar phenotypes are also discussed, illustrating the need for correlating IPT with morphology and clinical features.

Reactive tonsillar enlargement showing strong 18F-FDG uptake during the follow-up of follicular lymphoma

The 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a standard procedure for the diagnosis, staging, and restaging in lymphoma patients. However, a relative high rate of false-positive results has been reported. We report a case of a 40-year-old man with a previous history of a nodal follicular lymphoma, stage IVA, treated with R-CHOP, which showed strong 18F-FDG uptake in the Waldeyer's tonsillar ring during his follow-up, being considered highly suspicious of relapsed lymphoma. A surgical removal of the palatine tonsils and adenoids was performed, which showed reactive follicular hyperplasia. Furthermore, bone marrow biopsy revealed absence of neoplasia. The patient is still in follow-up with no signs of recurrent lymphoma. This case illustrates that, despite the high sensitivity for the detection of recurrent lymphoma, 18F-FDG uptake should be interpreted with great caution and confirmatory studies should be performed before any therapy.

Lung cancer in HIV Infection

Lung cancer is the most prevalent non-AIDS-defining malignancy in the highly active antiretroviral therapy era. Smoking plays a significant role in the development of HIV-associated lung cancer, but the cancer risk is two to four times greater in HIV-infected persons than in the general population, even after adjusting for smoking intensity and duration. Lung cancer is typically diagnosed a decade or more earlier among HIV-infected persons (mean age, 46 years) compared to those without HIV infection. Adenocarcinoma is the most common histological subtype, and the majority of patients are diagnosed with locally advanced or metastatic carcinoma. Because pulmonary infections are common among HIV-infected individuals, clinicians may not suspect lung cancer in this younger patient population. Surgery with curative intent remains the treatment of choice for early-stage disease. Although there is increasing experience in using radiation and chemotherapy for HIV-infected patients who do not have surgical options, there is a need for prospective studies because this population is frequently excluded from participating in cancer trials. Evidence-based treatments for smoking-cessation with demonstrated efficacy in the general population must be routinely incorporated into the care of HIV-positive smokers.

Human immunodeficiency virus-associated primary lung cancer in the era of highly active antiretroviral therapy: a multi-institutional collaboration

BACKGROUND

Human immunodeficiency virus (HIV)-infected individuals are at increased risk for primary lung cancer (LC). We wished to compare the clinicopathologic features and treatment outcome of HIV-LC patients with HIV-indeterminate LC patients. We also sought to compare behavioral characteristics and immunologic features of HIV-LC patients with HIV-positive patients without LC.

PATIENTS AND METHODS

A database of 75 HIV-positive patients with primary LC in the HAART era was established from an international collaboration. These cases were drawn from the archives of contributing physicians who subspecialize in HIV malignancies. Patient characteristics were compared with registry data from the Surveillance Epidemiology and End Results program (SEER; n = 169,091 participants) and with HIV-positive individuals without LC from the Adult and Adolescent Spectrum of HIV-related Diseases project (ASD; n = 36,569 participants).

RESULTS

The median age at HIV-related LC diagnosis was 50 years compared with 68 years for SEER participants (P < .001). HIV-LC patients, like their SEER counterparts, most frequently presented with stage IIIB/IV cancers (77% vs. 70%), usually with adenocarcinoma (46% vs. 47%) or squamous carcinoma (35% vs. 25%) histologies. HIV-LC patients and ASD participants had comparable median nadir CD4+ cell counts (138 cells/µL vs. 160 cells/µL). At LC diagnosis, their median CD4+ count was 340 cells/µL and 86% were receiving HAART. Sixty-three HIV-LC patients (84%) received cancer-specific treatments, but chemotherapy-associated toxicity was substantial. The median survival for both HIV-LC patients and SEER participants with stage IIIB/IV was 9 months.

CONCLUSION

Most HIV-positive patients were receiving HAART and had substantial improvement in CD4+ cell count at time of LC diagnosis. They were able to receive LC treatments; their tumor types and overall survival were similar to SEER LC participants. However, HIV-LC patients were diagnosed with LC at a younger age than their HIV-indeterminate counterparts. Future research should explore how screening, diagnostic and treatment strategies directed toward the general population may apply to HIV-positive patients at risk for LC.

Fine needle aspiration cytology and flow cytometry immunophenotyping of non-Hodgkin lymphoma: can we do better?

OBJECTIVE

To evaluate the diagnostic efficiency of fine needle aspiration cytology/flow cytometry (FNAC/FC) in the diagnosis and classification of non-Hodgkin lymphoma (NHL) in a series of 446 cases and to compare the results with those of previous experiences to evaluate whether there had been an improvement in FNAC/FC diagnostic accuracy.

METHODS

FNAC/FC was used to analyse 446 cases of benign reactive hyperplasia (BRH), NHL and NHL relapse (rNHL) in 362 lymph nodes and 84 extranodal lesions. When a diagnosis of NHL was reached, a classification was attempted combining FC data and cytological features. Sensitivity, specificity and positive and negative predictive values (PPV and NPV) of FNAC/FC in the diagnosis and classification of NHL were calculated and compared with those available in the literature.

RESULTS

FNAC/FC provided a diagnosis of NHL and rNHL in 245 cases and of BRH in 188 cases. In nine cases, the diagnosis was 'suggestive of NHL' (sNHL) and in four cases was inadequate. Histology and clinical follow-up confirmed 102 cases of NHL and detected one false positive. In 18 cases of BRH diagnosed by FNAC/FC, histological examination revealed 14 BRH and four NHL (false negatives). All nine cases diagnosed as sNHL were confirmed by histology. Including sNHL cases as false negatives, statistical analysis showed 94.9% sensitivity, 99.4% specificity, 99.6% PPV and 93.4% NPV in the diagnosis of NHL. A specific subtype was diagnosed in 125 cases and confirmed in 67 of 70 cases that had histological biopsies. Statistical analysis did not demonstrate significant improvements between the present series and previous studies either in diagnosis or in classification of NHL.

CONCLUSIONS

FNAC/FC is a fundamental tool in the diagnosis and classification of NHL but the exiguity of diagnostic material and other technical and clinical limitations will probably continue to limit further improvement of the technique.

Clonal B-cell population in a reactive lymph node in acquired immunodeficiency syndrome

A 40-year-old female, HIV positive, stage C, since 4 years, complained of a right cervical lymph node swelling. Two years before, the patient had been diagnosed with follicular B-cell non-Hodgkin lymphoma (FL); she had been treated with four cycles of multiagent chemotherapy plus rituximab, the last cycle being administered 10 months before coming to our attention. An ultrasound (US) guided fine-needle cytology (FNC) showed an atypical lymphoid cell proliferation. The phenotype evidenced by flow cytometry (FC) analysis was D5: 10%, CD19: 49%, CD23: 10%, FMC7: 0%, CD10: 40%, CD10/19: 40%, lambda light chain 40%, kappa light chain 0%. FDG-positron emission tomography (PET/CT) scan showed positivity in the corresponding cervical area. Since low LDH values and a reduced lymph node size were observed, the lymph node was therefore excised; the histology revealed a reactive hyperplastic lymph node with florid follicular pattern. A subsequent PCR analysis, performed on DNA extracted from a whole histological section, did not evidence IgH rearrangement. The patient is currently undergoing strict clinical and instrumental follow-up, including PET every 3 months; after 13 months, she is alive without recurrence of lymphoma. Clonal B-cell populations in non-lymphomatous processes have been described in mucosa-associated lymphoid cell populations and reactive lymph nodes, and are considered non-malignant, antigen driven, proliferations of B-lymphocytes determined by an abnormal response to bacterial or viral antigen stimulation. The present case occurred in an HIV patient and was clinically complex because of the patient's history of FL. This experience suggests much attention in the evaluation of radiological, cytological, and FC data and in clinical correlation in patients suffering from autoimmune or immunodeficiency syndromes.