Ondrejka, Sarah L.

Abstract Follicular lymphoma (FL) is clinically heterogeneous, with select patients tolerating extended watch-and-wait, whereas others require prompt treatment, suffer progression of disease within 24 months of treatment (POD24), and/or experience aggressive histologic transformation (t-FL). Because our understanding of the relationship between genetic alterations in FL and patient outcomes remains limited, we conducted a clinicogenomic analysis of 370 patients with FL or t-FL (from Cancer and Leukemia Group B/Alliance trials 50402/50701/50803, or real-world cohorts from Washington University School of Medicine, Cleveland Clinic, or University of Miami). FL subsets by grade, stage, watch-and-wait, or POD24 status did not differ by mutation burden, whereas mutation burden was significantly higher in relapsed/refractory (rel/ref) FL and t-FL than in newly diagnosed (dx) FL. Nonetheless, mutation burden in dx FL was not associated with frontline progression-free survival (PFS). CREBBP was the only gene more commonly mutated in FL than in t-FL yet mutated CREBBP was associated with shorter frontline PFS in FL. Mutations in 20 genes were more common in rel/ref FL or t-FL than in dx FL, including 6 significantly mutated genes (SMGs): STAT6, TP53, IGLL5, B2M, SOCS1, and MYD88. We defined a mutations associated with progression (MAP) signature as ≥2 mutations in these 7 genes (6 rel/ref FL or t-FL SMGs plus CREBBP). Patients with dx FL possessing a MAP signature had shorter frontline PFS, revealing a 7-gene set offering insight into FL progression risk potentially more generalizable than the m7–Follicular Lymphoma International Prognostic Index (m7-FLIPI), which had modest prognostic value in our cohort. Future studies are warranted to validate the poor prognosis associated with a MAP signature in dx FL, potentially facilitating novel trials specifically in this high-risk subset of patients.

Abstract Objectives Oil Red O (ORO) positivity in bronchoalveolar lavage (BAL) fluid macrophages in the setting of e-cigarette, or vaping, product use–associated acute lung injury (EVALI) has been frequently requested by clinicians based on rare reports and subsequent US Centers for Disease Control and Prevention guidelines. The aim of this study was to determine the specificity of ORO staining in BAL specimens with disease states other than EVALI. Methods Consecutive BAL specimens (October-December 2019) were stained with ORO. The lipid-laden macrophage index (LLMI) was calculated for each case. Results We studied BAL samples from 50 patients. Indications for BAL were surveillance bronchoscopy for lung transplantation (27/50), suspected infection (12/50), sarcoidosis/suspected sarcoidosis (3/50), nodules or ground-glass opacities (3/50), hemoptysis (2/50), asthma or eosinophilic pneumonia (2/50), and idiopathic pulmonary fibrosis (1/50). ORO staining was seen in BAL fluid macrophages in 45 of 50 cases (focal in 18, moderate in 23, diffuse in 4); LLMI ranged from 0 to 218. Using a threshold of LLMI of 85 or higher as positive, ORO was positive in 7 of 50 (14%) cases (range, 85-218). Conclusions ORO staining in BAL fluid macrophages is not specific for EVALI. Even when an LLMI of 85 or higher is used as a threshold for positivity, ORO positivity occurs in a significant subset of non–vaping-related cases.

PURPOSE Peripheral T-cell lymphoma (PTCL) includes heterogeneous clinicopathologic entities with numerous diagnostic and treatment challenges. We previously defined robust transcriptomic signatures that distinguish common PTCL entities and identified two novel biologic and prognostic PTCL-not otherwise specified subtypes (PTCL-TBX21 and PTCL-GATA3). We aimed to consolidate a gene expression–based subclassification using formalin-fixed, paraffin-embedded (FFPE) tissues to improve the accuracy and precision in PTCL diagnosis. MATERIALS AND METHODS We assembled a well-characterized PTCL training cohort (n = 105) with gene expression profiling data to derive a diagnostic signature using fresh-frozen tissue on the HG-U133plus2.0 platform (Affymetrix, Inc, Santa Clara, CA) subsequently validated using matched FFPE tissues in a digital gene expression profiling platform (nCounter, NanoString Technologies, Inc, Seattle, WA). Statistical filtering approaches were applied to refine the transcriptomic signatures and then validated in another PTCL cohort (n = 140) with rigorous pathology review and ancillary assays. RESULTS In the training cohort, the refined transcriptomic classifier in FFPE tissues showed high sensitivity (> 80%), specificity (> 95%), and accuracy (> 94%) for PTCL subclassification compared with the fresh-frozen–derived diagnostic model and showed high reproducibility between three independent laboratories. In the validation cohort, the transcriptional classifier matched the pathology diagnosis rendered by three expert hematopathologists in 85% (n = 119) of the cases, showed borderline association with the molecular signatures in 6% (n = 8), and disagreed in 8% (n = 11). The classifier improved the pathology diagnosis in two cases, validated by clinical findings. Of the 11 cases with disagreements, four had a molecular classification that may provide an improvement over pathology diagnosis on the basis of overall transcriptomic and morphological features. The molecular subclassification provided a comprehensive molecular characterization of PTCL subtypes, including viral etiologic factors and translocation partners. CONCLUSION We developed a novel transcriptomic approach for PTCL subclassification that facilitates translation into clinical practice with higher precision and uniformity than conventional pathology diagnosis.

Objectives: Signet-ring cells (SRCs) in effusion specimens represent a diagnostic challenge. In this study, a consecutive series of pleural and peritoneal effusions with benign SRCs are examined and compared with malignant SRCs. Material and Methods: We reviewed consecutive Wright-stained serous effusion slides and searched for cases with SRCs. Corresponding ThinPrep slides and clinical histories were reviewed. Cytology cases with known signet-ring adenocarcinoma were retrieved and reviewed. Results: Four hundred Wright-stained serous effusions were reviewed. Eighteen cases were identified with SRC-like cells. Thirteen patients had liver cirrhosis, three patients had end-stage renal disease, one patient had a history of pancreatic adenocarcinoma, and one patient had endometrioid carcinoma. For the latter two patients, the primary tumor showed no histologic findings of signet-ring features. In all cases, no SRCs were found on the corresponding ThinPrep slides. Five cytology cases with malignant SRCs were reviewed. Benign SRCs have a uniformly pale and markedly distended cytoplasm, and the nuclei are thin and curved. The malignant SRCs showed larger non-curved nuclei and bubbly mucin-containing cytoplasm. Conclusion: Mesothelial cells and histiocytes can mimic signet-ring adenocarcinoma cells on Wright-stained slides. Correlation with ThinPrep specimens is necessary before reporting, as the SRCs typically are not present in ThinPrep preparations.

Abstract Abstract 1545 Introduction: The diagnosis of peripheral T-cell lymphoma (PTCL) is difficult and accurate diagnosis and subclassification relies on correlating histologic, immunophenotypic, molecular genetic, and clinical data. Evidence-based guidelines for the appropriate diagnostic work-up of PTCL are lacking. The objective of this study was to evaluate a large series of PTCLs by experienced hematopathologists with a tiered approach to immunohistochemistry (IHC) and molecular genetic characterization to document overall diagnostic accuracy and clinical relevance using this approach. Methods: 7 experienced hematopathologists from 5 institutions reviewed 374 cases of peripheral T and NK cell lymphomas (referred to collectively as PTCL). 6 cases of cutaneous T-cell lymphoma were excluded after final review in addition to 29 non-PTCL cases submitted as control cases to mimic diagnostic practice during the review. Cases received tier 0, 1 and 2 diagnoses by 3 independent pathologists, based on review of hematoxylin and eosin (HE) stain with basic demographic data, panel 1 IHC (CD3, CD5, CD10, CD20, CD21, CD30, CD45, PAX5), and panel 2 IHC (CD2, CD4, CD7, CD8, CD23, PD1, CD56, EBER, ALK, TIA1, TCRg, TCRbF1), respectively. A tier 2b diagnosis was then rendered after gene rearrangement data were available. A final consensus diagnosis was rendered after discussion of each case by the 3 reviewers with all available clinical data. Overall survival (OS) was assessed using Kaplan-Meier (KM) curves and Cox proportional hazards models. Results: 1122 individual diagnoses leading to 339 final consensus PTCL diagnoses were rendered. 341 (91%) cases had complete phenotypic data and 241 had gene rearrangement data. There was no bias of missing data according to final diagnosis subtype. Reviewer diagnoses using specific WHO subclassification were 16.3%, 36.9%, 82.7%, and 85.9% for tier 0, 1, 2, and 2b, demonstrating a significant increase in diagnostic certainty after a complete IHC panel. Gene rearrangement only contributed to a change in diagnosis in 51/650 (8%) individual reviews. Across all 374 cases, a small number of cases (n=28, 7.5%) showed no agreement among the 3 independent reviewers after tier 2b and required debate. These generally represented refinement of the subclassification of a PTCL. The most common disagreements were between PTCL, not otherwise specified (nos) vs. unclassifiable T-cell lymphoma, and PTCL, nos vs. angioimmunoblastic T-cell lymphoma (AITL). Currently, OS data was available in 198 cases and 52% have died (median age follow-up of 15 months for those still alive, range 0–160 mo). Figure 1 shows the KM survival curves for types with more than 10 cases. Of note, unclassifiable PTCL cases had poor OS, comparable to PTCL nos; a trend was seen for CD30+ ALK- ALCL to have a longer OS compared to PTCL nos (HR=0.5, 95% CI: 0.21–1.19, P=.09). EBER positivity in tumor cells was associated with poor OS in the cohort of all PTCL patients (HR=2.32, 95% CI: 1.28–4.23, p=0.006, Figure 2); the association was similar when nasal NK/T-cell lymphoma cases were excluded (HR=2.50, 95% CI: 1.00–6.26, p=0.05). Trends for poor prognosis were also seen for TIA-1 expression in PTCL, nos (HR=1.9, 95% CI 0.91–3.96, P=.09) and PD1 expression in AITL (HR=6.25, 95% CI 0.85–46.09, P=.07). Clinical data collection is still ongoing and will be updated. Conclusions: We demonstrate the diagnostic accuracy among experienced hematopathologists of a defined IHC panel, showing an overall ability to reach consensus diagnosis of 93% in PTCL cases. The resulting consensus diagnostic subtypes showed expected outcomes relative to other large series of PTCLs, and EBER positivity is a poor prognostic marker among T and NK cell lymphomas. A tiered approach to IHC is recommended when a PTCL is under differential diagnostic consideration since the first tier can often resolve the main question of whether a lesion is reactive or lymphoma. This can lead to more efficient use of the expanded tier 2 panel that will enable diagnosis and specific subclassification of PTCL. Gene rearrangement studies are not required in the great majority of cases. This evidence-based approach to the diagnosis of PTCL should inform practicing pathologists, clinical trial design, and policy makers regarding required ancillary studies in this group of diseases. Disclosures: Hsi: Allos: Research Funding. Said:Allos: Research Funding. Macon:Allos: Research Funding. Rodig:Allos: Research Funding. Gascoyne:Seattle Genetics: Research Funding. Ondrejka:Allos: Research Funding. Dorfman:Allos: Research Funding. Maurer:Allos: Research Funding. Dogan:Allos: Research Funding.

One-third of peripheral T-cell lymphomas are “not otherwise specified” (PTCL-NOS), but they have been subdivided into 2 subgroups based on gene expression profiling. Amador and colleagues generated an immunohistochemical algorithm that parallels the molecular separation of PTCL-NOS and provides useful prognostic information.

Key Points ALK-negative ALCLs have chromosomal rearrangements of DUSP22 or TP63 in 30% and 8% of cases, respectively. DUSP22-rearranged cases have favorable outcomes similar to ALK-positive ALCLs, whereas other genetic subtypes have inferior outcomes.