Diagnosis of Lymphoid Lesions in Limited Samples

A Guide for the General Surgical Pathologist, Cytopathologist, and Cytotechnologist

Hector Mesa, MD; Ajay Rawal, MD; Pankaj Gupta, MD

Disclosures

Am J Clin Pathol. 2018;150(6):471-484. 

In This Article

Abstract and Introduction

Abstract

Objectives: Advances in interventional techniques allow obtaining samples from most body sites through minimally invasive procedures that yield limited samples. We provide practical guidelines for diagnosis of lymphoid lesions in these samples.

Methods: Guidelines for selection of biopsy site and triage of the specimen according to results of rapid on-site evaluation (ROSE), and description of the advantages and limitations of currently available ancillary studies are described, based on the experience of the authors, complemented by a comprehensive review of the literature.

Results: Five diagnostic categories are observed at ROSE: (1) preponderance of small cells, (2) large cells, (3) mixed small and large cells, (4) blast-like cells, and (5) rare large pleomorphic cells. Detailed description of the diagnostic work-up and subsequent classification for each of these groups is provided.

Conclusions: A definitive diagnosis of lymphoid neoplasms in limited samples is possible in most cases through correlation of morphology, ancillary studies, and clinical scenario.

Introduction

Recent advances in medical imaging have resulted in improved and earlier detection of tumoral lesions and lymphadenopathy. This development has been accompanied by advances in interventional radiology and endoscopic techniques that allow obtaining tissue samples from virtually any body site through minimally invasive procedures with very low rates of complications. For morphologists, this trend has resulted in progressively smaller tissue samples in which tissue architecture, an important parameter for establishing a histologic diagnosis, is difficult to assess or no longer evaluable. While excisional/large incisional biopsies are ideal for diagnosis and ancillary testing, nowadays in many centers, including ours, the initial diagnostic approach for suspected lymphomas includes fine-needle aspirates (FNAs), FNAs with cell block, and core needle biopsies (CNBs).[1,2] A search of the electronic pathology database at the Minneapolis Veterans Administration (VA) Medical Center showed that the diagnosis of lymphoma in limited samples of lymph nodes (FNAs or CNBs) was 15% in 1991 (n = 26), 20% in 2004 (n = 25), and 70% in 2016 (n = 59). Similarly, Amador-Ortiz et al[1] reported an increase from 28% in 2003 to 70% in 2007 at a tertiary center, reflecting a trend that is occurring in many centers around the world. Difficulties in establishing a reliable diagnosis in these samples have been at least partially offset by continuous advances in ancillary techniques. These techniques provide objective supporting evidence for establishing clonality, assessing cell lineage/aberrant antigenic expression, and evaluating for tumor-specific translocations or mutations. Recent studies on the use of FNAs and CNBs for establishing and subclassifying lymphomas report diagnostic success rates ranging from 75% to 98%.[1,2]

Some of the studies used for pathologic diagnosis have now become targeted therapy-specific ancillary tests (eg, CD20, CD30, CD52, ALK, BCL2). Equally important, the adoption of electronic medical records by most medical centers gives pathologists access to clinical and radiologic information for optimal clinicopathologic correlation.

To guide clinical decision making, the oncologist looks for the following information from the pathologist: Is the lesion benign or malignant? If malignant, is it a lymphoma, and if so, is a definitive subclassification possible? Since each diagnostic category of lymphoma is a unique disease entity with characteristic morphology, immunophenotype, molecular genetics, and gene expression profile, precise identification is of utmost importance for prognostication and therapy. Further evaluation, and the urgency with which it needs to be undertaken, depends on the type and grade of lymphoma: for low-grade lymphoid neoplasms (eg, low-grade follicular lymphoma [FL], marginal zone lymphoma [MZL], or small lymphocytic lymphoma [SLL]), workup for staging and determining the need for treatment vs observation can be arranged electively on an outpatient basis. For intermediate-grade lymphomas, such as diffuse large B-cell lymphoma (DLBCL) or grade 3 FL, expedited staging workup, assessment of cardiac function, and initiation of combination chemoimmunotherapy (eg, rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone [R-CHOP] regimen) are indicated. If a high-grade lymphoma is present (eg, Burkitt lymphoma [BL], acute lymphoblastic leukemia/lymphoblastic lymphoma [ALL/LBL]), then urgent workup, including assessment of cardiac function and sampling of the cerebrospinal fluid, aggressive hydration, and prophylaxis against tumor lysis followed by initiation of intensive multiagent chemoimmunotherapy and central nervous system (CNS) prophylaxis, usually in the inpatient setting, is required. In addition, identification of specific lymphoma subtypes such as mantle cell lymphoma (MCL), anaplastic large cell lymphoma (ALCL), classical Hodgkin lymphoma (CHL) vs nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL), or the presence of molecular therapeutic targets, such as the BCR/ABL translocation, is critical to determination of prognosis and treatment. In addition to a specific diagnosis, the clinician may seek additional information from the pathologist for selection of therapy. For some of the most common lymphoid disorders, these are as follows:

  • Chronic lymphocytic leukemia (CLL): Interphase fluorescent in situ hybridization (FISH) for detection of prognostically relevant chromosomal abnormalities, sequencing for TP53 mutations, karyotype for detection of complex cytogenetic abnormalities, and molecular analysis for detection of immunoglobulin heavy chain variable region mutation status. Whether del(17p)/TP53 mutations are present or absent is of particular relevance for prognosis and treatment.[3]

  • FL: FISH detection of t(14;18), BCL6, 1p36, and IRF4/MUM1 rearrangements to determine whether the lymphoma represents typical FL, FL with 1p36 deletion, or cutaneous or pediatric-type FL (in adults) for planning optimal treatment and prognosis.[4]

  • DLBCL: Distinguish germinal center B-cell (GCB) vs non-GCB (activated B-cell) cell of origin by ancillary tests. Karyotype or FISH for detection of MYC, BCL2, and BCL6 rearrangements, to identify double- and triple-hit DLBCL. These two aspects (cell of origin and double/triple hit) are of particular relevance for prognosis, optimal treatment, and referral for clinical trials.[4–6]

The interested reader is advised to consult the most current version of standard sources such as the National Comprehensive Cancer Network guidelines for up-to-date and detailed information about the specific test results the clinician looks for to determine prognosis and guide treatment for the wide variety of lymphoid malignancies at https://www.nccn.org.

The authors describe here their approach to the evaluation of lymphoid lesions, aimed at serving as a guide for the general pathologist.

Dr Gupta is professor of medicine in the Division of Hematology/Oncology/Transplantation at the University of Minnesota and staff physician in hematology/oncology at the Minneapolis VA Medical Center, Minneapolis, a tertiary referral academic hospital with one of the largest tumor registries in the VA system. As a faculty member for over 23 years, he has been actively involved in clinical practice, teaching, and basic and clinical research. Dr Mesa is a surgical pathologist and hematopathologist with 19 years' experience. He provides consultation services in hematopathology, flow cytometry, immunology, and coagulation to VA hospitals in the Midwest and Ohio Veterans Integrated Service Networks. Dr Rawal is a surgical pathologist and hematopathologist with 18 years of experience, currently working at Health Partners, a large consortium of over 90 clinics and hospitals, serving 1.2 million patients annually.

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