Indolent T-lymphoblastic proliferation in Castleman lymphadenopathy

Indolent T-lymphoblastic proliferation involving hepatocellular carcinoma-presentation in novel settings and comprehensive review of literature

Indolent T-lymphoblastic proliferation (iT-LBP) is a rare, non-clonal, extrathymic lymphoid proliferation with an immature T cell phenotype, indolent clinical course, and excellent prognosis. Although their pathogenesis is unclear, they are reported to be associated with Castleman disease, follicular dendritic cell tumors/sarcomas, angioimmunoblastic T cell lymphoma, hepatocellular carcinoma (HCC), myasthenia gravis, and acinic cell carcinoma. There are around 51 reported cases of iT-LBP in the literature. Recognition and accurate diagnosis of this entity is critical as it shares morphologic and immunophenotypic features with an aggressive malignancy-acute T cell leukemia/lymphoma (T-ALL). IT-LBP in HCC post-liver transplant and in metastatic sites has not been reported in the literature. Two case reports of patients presenting with recurrent and metastatic HCC in post-liver transplant settings are described. A 50-year-old man with an end-stage liver disease with HCC underwent liver transplant. A year later, he developed pulmonary metastasis with associated iT-LBP. A 69-year-old man underwent liver transplant for end-stage liver disease and HCC. Eighteen months later, he developed recurrent HCC in the transplanted liver and omental metastasis; both sites showed HCC with iT-LBP. iT-LBP in both patients expressed TdT, CD3, and CD4 and lacked CD34 and clonal T cell receptor gene rearrangements. On retrospective review, the pre-transplant HCC specimens lacked iT-LBP. We present two cases of iT-LBP associated with HCC in novel settings-in post-liver transplant patients and in recurrent/metastatic sites of HCC. In addition, a comprehensive literature review of clinical, histological, and immunophenotypic characteristics of reported cases of iT-LBP is presented.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms

We herein present an overview of the upcoming 5^th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4^th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5^th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

Indolent T-lymphoblastic proliferation: A systematic review of the literature analyzing the epidemiologic, clinical, and pathologic features of 45 cases

An indolent T-lymphoblastic proliferation (iT-LBP) is a rare benign disorder characterized by an abnormal expansion of immature T-cells, which morphologically can mimic malignancy. Since the first case was described in 1999, dozens more have been reported in the literature. However, the epidemiologic, clinical, pathologic, and biologic features of this disease have not been well described. Here, we retrospectively reviewed all known cases reported in the literature to better understand this entity. A PubMed search up to January 2022 highlighted 25 papers describing cases/case series of iT-LBP, one of which was a case presentation in a slide workshop. Except for 9 of the cases in one of the papers, where it was evident that the number of CD3+/TdT+ cells were too few to conform with a diagnosis of iT-LBP, all papers and all the cases reported were included in the study amounting to a total of 45 cases. Clinicopathologic characteristics were analyzed using descriptive statistics and frequencies. Our analysis highlighted the previously known association with Castleman disease and Castleman-like features and underlined its association with dendritic cell proliferations in general, as well as uncovering high frequency of concurrence with hepatocellular carcinoma and autoimmune diseases, most notably myasthenia gravis, paraneoplastic pemphigus and paraneoplastic autoimmune multiorgan syndrome. Furthermore, the co-expression of CD4 and CD8 and high prevalence of extranodal disease and recurrences were other less well described features that were revealed.

Indolent T-Lymphoblastic Proliferation in Idiopathic Multicentric Castleman Disease

Benign and polyclonal proliferation of immature T cells in a lymph node with preserved morphological architecture is called indolent T-lymphoblastic proliferation (iT-LBP). Although overall rare, they have been described in association with both benign and malignant disorders including Castleman disease. We report the first case of idiopathic multicentric Castleman disease associated with iT-LBP, all previous reports of iT-LBP in Castleman disease were unicentric. A 37-year-old-male presented with 3 months of fevers and B-symptoms and was found to have enlargement of multiple bilateral lymph node sites on both sides of diaphragm along with splenomegaly. Anemia, elevated C-reactive protein, hypoalbuminemia, and elevated interleukin-6 levels were present. Biopsy of a lymph node showed features suggestive of idiopathic multicentric Castleman disease and iT-LBP. Bone marrow biopsy was unremarkable. Siltuximab and steroids were used to treat the condition.

Indolent T-lymphoblastic proliferation: a report of three cases

Indolent T-lymphoblastic proliferation (iT-LBP) is the extrathymic proliferation of nonclonal TdT + T cells and is typically associated with lymphoid disorders. Although one study revealed that iT-LBP occurred in angioimmunoblastic T-cell lymphoma, no other lymphoma-related cases have been reported. Here, we report three cases of concurrent iT-LBP and benign or malignant lymphoid disorders. The first patient had bilateral cervical lymph node enlargement, and the resected lymph node showed polyclonal precursor T-cells distributed between benign hyperplastic lymphoid follicles. In the second case, iT-LBP occurred in peripheral T-cell lymphoma with a follicular growth pattern, showing that precursor T-cells were distributed between neoplastic follicles composed of CD4 + and CXCL13 + T-cells. In the third case, polyclonal precursor T-cells were distributed between the neoplastic follicles of follicular lymphoma. In summary, our results indicate an association between iT-LBP and reactive lymphoid hyperplasia (case 1) and lymphoma (cases 2 and 3).

[Indolent T-lymphoblastic proliferation in association with localized Castleman disease: A case report]

Herein we report the case of a 41-year-old woman who presented with pelvic pain. Magnetic Resonance Imaging exhibited a single pelvic mass, measuring 50mm long axis, alongside the right iliac vessels. Histological examination of the excision specimen showed a lymphoid tumor with features of localized Castleman disease, hyaline vascular type. Moreover we identified multiple interfollicular dark clusters, composed of cells morphologically resembling cortical thymocytes. Their immunophenotype was consistent with an intermediate stage of T-cell differentiation, with the expression of CD3, CD4, CD8, TdT, CD1a, CD99, CD2, CD5, CD7 and CD10, with 40% Ki67. After integration of clinical and molecular data, the retained diagnosis was an indolent T-cell lymphoblastic proliferation associated with hyaline vascular localized Castleman disease. The clinical course confirmed the indolent nature of the proliferation, despite a late local recurrence at 7 years of the initial diagnosis, without histological modification, due to an incomplete initial resection surgery.

Indolent T-lymphoblastic proliferation concomitant with acinic cell carcinoma mimicking T-lymphoblastic lymphoma: case report and literature review

AIMS

Indolent T-lymphoblastic proliferation (iT-LBP) is a non-clonal benign condition showing extrathymic proliferation of T-lymphoblasts positive for CD3, CD4, CD8, and TdT. Isolated iT-LBP has been observed, but the majority of iT-LBPs have been seen in conjunction with other disorders, including Castleman disease, hepatocellular carcinoma, follicular dendritic cell tumours, angioimmunoblastic T-cell lymphoma, myasthenia gravis, and acinic cell carcinoma (ACC). The clinical course of iT-LBP is indolent, and no therapy is usually required. A major concern is misdiagnosis as T-lymphoblastic lymphoma, and a correct diagnosis of iT-LBP often requires not only pathological analysis but also careful monitoring of the clinical course. The aim of this study was to broaden the knowledge of pathologists and physicians concerning this as yet not well-recognised entity.

METHODS AND RESULTS

We report a case of iT-LBP concomitant with ACC, along with a literature review of all 14 cases of iT-LBP reported to date.

CONCLUSIONS

iT-LBP should always be considered as a differential diagnosis of T-lymphoblastic lymphoma, as the two disorders show extremely similar traits.

Indolent T-lymphoblastic proliferation with disseminated multinodal involvement and partial CD33 expression

Although indolent T-lymphoblastic proliferations (iT-LBP) are rare, this diagnosis should be excluded in any patient with an extrathymic proliferation of immature TdT+T cells. Unlike T-lymphoblastic leukemia/lymphoma, patients with iT-LBP do not require chemotherapy. We report a case of iT-LBP with disseminated multinodal involvement in an otherwise healthy 49-year-old woman. Multiple lymph node biopsies were performed over the course of several months demonstrating persistent and anatomically diffuse involvement. Over 18 months, and without therapy, she has remained healthy, and her lymphadenopathy significantly improved. No bone marrow or peripheral blood involvement was ever identified. Atypical T cells showed an immunophenotypic spectrum of T-cell antigen expression with partial CD33 on a subset of T cells detected by both flow cytometry and immunohistochemistry. Both T-cell clonality and Human Androgen Receptor Assay (HUMARA) studies, performed on lymph node biopsy specimens, were negative. This case represents the first detailed clinical, morphologic, molecular, and immunophenotypic description of disseminated multinodal involvement by nonclonal iT-LBP with partial CD33 expression on T cells.

Indolent T-lymphoblastic proliferation (iT-LBP): a review of clinical and pathologic features and distinction from malignant T-lymphoblastic lymphoma

In recent years, a new pathologic entity has emerged: indolent T-lymphoblastic proliferation (iT-LBP). iT-LBPs share immunophenotypic similarities with T-lymphoblastic lymphoma; however, T-lymphoblastic proliferations are clinically indolent, and unlike the malignant counterpart, these expansions of nonclonal terminal deoxynucleotidyl transferase (TdT)+ T cells do not require treatment. Here we review the clinical and pathologic features, which are required for an accurate diagnosis of an iT-LBP. We demonstrate specific criteria can be used to accurately diagnose iT-LBP, notably: (1) confluent groups of TdT+ T cells in a biopsy specimen, (2) relative preservation of surrounding normal lymphoid architecture, (3) TdT+ T cells without morphologic atypia, (4) absence of thymic epithelium, (5) nonclonal TdT+ T cells, (6) immunophenotype of developmentally normal immature thymic T cells, and (7) clinical evidence of indolence (follow-up >6 mo without progression).