Enteropathy-associated intestinal T-cell lymphoma in cavitating mesenteric lymph node syndrome: Fine-needle aspiration contributes to the diagnosis

A Proposal for the Performance, Classification, and Reporting of Lymph Node Fine-Needle Aspiration Cytopathology: The Sydney System

BACKGROUND

The evaluation of lymph nodes (LN) by fine-needle aspiration cytology (FNAC) is routinely used in many institutions but it is not uniformly accepted mainly because of the lack of guidelines and a cytopathological diagnostic classification. A committee of cytopathologists has developed a system of performance, classification, and reporting for LN-FNAC.

METHODS

The committee members prepared a document that has circulated among them five times; the final text has been approved by all the participants. It is based on a review of the international literature and on the expertise of the members. The system integrates clinical and imaging data with cytopathological features and ancillary techniques. The project has received the endorsement and patronage of the International Academy of Cytology and the European Federation of the Cytology Societies.

RESULTS

Clinical, imaging, and serological data of lymphadenopathies, indications for LN-FNAC, technical procedures, and ancillary techniques are evaluated with specific recommendations. The reporting system includes two diagnostic levels. The first should provide basic diagnostic information and includes five categories: inadequate/insufficient, benign, atypical lymphoid cells of undetermined/uncertain significance, suspicious, and malignant. For each category, specific recommendations are provided. The second diagnostic level, when achievable, should produce the identification of specific benign or malignant entities and additional information by utilizing ancillary testing.

CONCLUSION

The authors believe that the introduction of this system for performing and reporting LN-FNAC may improve the quality of the procedure, the report, and the communication between cytopathologists and the clinicians. This system may lead to a greater acceptance and utilization of LN-FNAC and to a better interdisciplinary understanding of the results of this procedure.

T- and NK-cell lymphoproliferative disorders of the gastrointestinal tract: review and update

T- and NK-cell lymphoproliferative disorders of the gastrointestinal (GI) tract are uncommon, but are important to recognise as there may be morphological and immunophenotypic overlap between lymphoid lesions with vastly different clinical outcomes. Recent data have led to the reclassification of some lymphomas and inclusion of new entities in the 2016 revision of World Health Organization (WHO) classification of lymphoid neoplasms. It has become clear that enteropathy associated T-cell lymphoma (EATL), formerly thought to be composed of two subtypes known as type I and type II, are distinct entities. Type I EATL is now simply classified as EATL; it is strongly associated with coeliac disease and occurs mainly in Western populations. Type II EATL has been renamed monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL); it shows no definite association with coeliac disease and occurs worldwide with a predominance in Asian populations. There is also a group of aggressive intestinal T-cell lymphomas which do not meet criteria for EATL, MEITL, extranodal NK/T-cell lymphoma of nasal type or anaplastic large cell lymphoma. These neoplasms are now designated intestinal T-cell lymphoma, not otherwise specified. Indolent T-cell lymphoproliferative disorder of the GI tract has been included as a provisional entity in the most recent WHO classification. It is a clonal T-cell lymphoproliferative disorder (CD4+ or CD8+) with an indolent clinical course. Finally, benign NK-cell proliferations of the GI tract, variably designated 'NK-cell enteropathy' and 'lymphomatoid gastropathy' have also been recognised in the last two decades but have not been included in the WHO classification as their neoplastic nature is not established. This review covers the aforementioned lymphoid proliferations, emphasising their salient clinicopathological features and genetic abnormalities. It also provides practical insights into resolving difficult differential diagnoses in daily surgical pathology practice.

Pathology of T-cell lymphomas: diagnosis and biomarker discovery

T-cell lymphomas are a group of predominantly rare hematologic malignancies that tend to recapitulate different stages of T-cell development, in a similar way that B-cell lymphomas do. As opposed to B-cell lymphomas, the understanding of the biology and the classification of T-cell lymphomas are somewhat rudimentary, and numerous entities are still included as 'provisional categories' in the World Health Classification of hematolopoietic malignancies. A relevant and useful classification of these disorders have been difficult to accomplish because of the rarity nature of them, the relative lack of understanding of the molecular pathogenesis, and their morphological and immunophenotypical complexity. Overall, T-cell lymphomas represent only 15 % of all non-Hodgkin lymphomas. This review is focused on addressing the current status of the categories of mature T-cell leukemias and lymphomas (nodal and extranodal) using an approach that incorporates histopathology, immunophenotype, and molecular understanding of the nature of these disorders, using the same philosophy of the most recent revised WHO classification of hematopoietic malignancies.