Causes of hypereosinophilia in 100 consecutive patients.

BACKGROUND: Hypereosinophilia (HE, persistent peripheral blood eosinophilia > 1.5 × 109 /L) and hypereosinophilic syndrome (HES, HE with end-organ damage) are classified as primary (due to a myeloid clone), secondary (due to a wide variety of reactive causes), or idiopathic. Diagnostic evaluation of eosinophilia is challenging, in part because secondary causes of HE/HES such as lymphocyte-variant HES (L-HES) and vasculitis are difficult to diagnose, and emerging causes such as immunoglobulin G4-related disease (IgG4-RD) have rarely been examined. OBJECTIVE AND METHODS: We reviewed 100 consecutive patients with HE/HES who underwent extensive evaluation for primary and secondary eosinophilia at a single tertiary care center to determine causes of HE/HES in a modern context. RESULTS: Six patients had primary HE/HES, 80 had a discrete secondary cause identified, and 14 had idiopathic HE/HES. The most common causes of secondary eosinophilia were L-HES/HES of unknown significance (L-HESus) (20), IgG4-RD (9), and eosinophilic granulomatosis with polyangiitis (EGPA) (8). CONCLUSIONS: In contrast to other large published series of HE/HES, most patients in this study were found to have a discrete secondary cause of eosinophilia and only 14 were deemed idiopathic. These findings highlight the importance of extensive evaluation for secondary causes of eosinophilia such as L-HES, IgG4-RD, and EGPA.

Canadian anaplastic lymphoma kinase study: a model for multicenter standardization and optimization of ALK testing in lung cancer.

INTRODUCTION: Fluorescence in situ hybridization (FISH) is currently the standard for diagnosing anaplastic lymphoma kinase (ALK)-rearranged (ALK+) lung cancers for ALK inhibitor therapies. ALK immunohistochemistry (IHC) may serve as a screening and alternative diagnostic method. The Canadian ALK (CALK) study was initiated to implement a multicenter optimization and standardization of laboratory developed ALK IHC and FISH tests across 14 hospitals. METHODS: Twenty-eight lung adenocarcinomas with known ALK status were used as blinded study samples. Thirteen laboratories performed IHC using locally developed staining protocols for 5A4, ALK1, or D5F3 antibodies; results were assessed by H-score. Twelve centers conducted FISH using protocols based on Vysis' ALK break-apart FISH kit. Initial IHC results were used to optimize local IHC protocols, followed by a repeat IHC study to assess the results of standardization. Three laboratories conducted a prospective parallel IHC and FISH analysis on 411 consecutive clinical samples using post-validation optimized assays. RESULTS: Among study samples, FISH demonstrated 22 consensus ALK+ and six ALK wild type tumors. Preoptimization IHC scores from 12 centers with 5A4 and the percent abnormal cells by FISH from 12 centers showed intraclass correlation coefficients of 0.83 and 0.68, respectively. IHC optimization improved the intraclass correlation coefficients to 0.94. Factors affecting FISH scoring and outliers were identified. Post-optimization concurrent IHC/FISH testing in 373 informative cases revealed 100% sensitivity and specificity for IHC versus FISH. CONCLUSIONS: Multicenter standardization study may accelerate the implementation of ALK testing protocols across a country/region. Our data support the use of an appropriately validated IHC assay to screen for ALK+ lung cancers.

Increased incidence of spontaneous apoptosis in the bone marrow of hyperdiploid childhood acute lymphoblastic leukemia.

OBJECTIVE: Hyperdiploidy of 51-65 chromosomes is associated with a good prognosis in childhood B-lineage acute lymphoblastic leukemia (ALL). Blasts from childhood ALL patients with a hyperdiploid karyotype have a tendency to apoptosis when cultured on stromal layers in vitro. In this study, we apply a novel method to investigate the relationship between apoptosis and hyperdiploidy in lymphoblasts of childhood ALL. MATERIALS AND METHODS: The DNA content of individual ALL blasts in Feulgen-stained archival bone marrow smears can be determined by static cytometry. TUNEL (TdT-mediated dUTP-biotin nick end labeling) detects the DNA degradation associated with apoptosis. We performed TUNEL in situ sequential to DNA ploidy analysis in archival bone marrow smears from 12 patients with childhood ALL. RESULTS: Five patients were diploid and seven were hyperdiploid (51-65 chromosomes) by conventional cytogenetic analysis. In the five diploid cases, the percentage of TUNEL-positive blasts ranged from 1.0% to 1.3%; in the seven hyperdiploid cases, the percentage of TUNEL-positive blasts ranged from 3.6% to 9.0%. Comparing TUNEL and corresponding Feulgen images, we found that apoptotic blasts were predominantly of high DNA ploidy in both diploid and hyperdiploid cases. The mean DNA value of apoptotic blasts was larger than that of the total blast population in each case. CONCLUSIONS: The results demonstrate an increased incidence of spontaneous apoptosis in situ of hyperdiploid blasts in ALL bone marrow and indicate that this phenomenon is not restricted to in vitro cultures. The findings provide a possible rationale for the good prognosis associated with hyperdiploid childhood ALL.