Indolent T-lymphoblastic proliferation: report of a case with an 11-year history and association with myasthenia gravis

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.

Indolent T-lymphoblastic proliferation with fibrolamellar hepatocellular carcinoma developed after colorectal adenocarcinoma: a case report

Objective: Indolent T-lymphoblastic proliferation (iT-LBP) is a non-neoplastic disease with an indolent clinical course, manifesting as hyperplasia of immature extrathymic T-lymphoblastic cells. Isolated iT-LBP has been observed, but the majority of iT-LBP cases has been seen in conjunction with other diseases. iT-LBP is easily misdiagnosed as T-lymphoblastic lymphoma/leukemia, and understanding the disease of indolent T-lymphoblastic proliferation may prevent misdiagnosis and missed diagnosis in pathological diagnosis. Case presentation: We report a case morphology, immunophenotypic, and molecular features of iT-LBP combined with fibrolamellar hepatocellular carcinoma developed after colorectal adenocarcinoma and review relevant literature. Conclusion: iT-LBP combined with fibrolamellar hepatocellular carcinoma developed after colorectal adenocarcinoma is relatively rare and should always be considered as a differential diagnosis of T-lymphoblastic lymphoma and scirrhous hepatocellular carcinoma as the two disorders show highly similar clinical features.

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: 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).

Myasthenia Gravis and Large Granular Lymphocytic Leukemia: a rare association

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disorder sometimes observed in hematologic malignancies as a paraneoplastic syndrome. T-cell Large Granular Lymphocytic Leukemia (T-LGLL) is a rare lymphoproliferative clonal frequently associated with autoimmune disorders. Here we report two patients with T-LGLL who developed MG. In both patients the MG was bulbar without generalized weakness and did not involve the thymus. The treatment of T-LGLL led to the resolution of MG symptoms and decrease in acetylcholine receptor antibody titers in both patients suggesting a causative association.

LIM domain only 2 (LMO2) expression distinguishes T-lymphoblastic leukemia/lymphoma from indolent T-lymphoblastic proliferations

AIMS

An indolent T-lymphoblastic proliferation (iT-LBP) is a benign, reactive expansion of immature terminal deoxynucleotidyl transferase (TdT)-positive T cells found in extrathymic tissues. iT-LBP can be challenging to distinguish from malignant processes, specifically T-lymphoblastic lymphoma (T-LBL), given the overlapping clinical and histological features. Recently, it has been shown that LIM domain only 2 (LMO2) is overexpressed in T-LBL but not in reactive immature TdT+ T cells in the thymus. On the basis of these findings, the aim of this study was to investigate the expression of LMO2 by using immunohistochemistry and its role in differentiating iT-LBPs from T-LBLs.

METHODS AND RESULTS

We retrospectively identified cases of iT-LBP and T-LBL from the pathology archives of four institutions. Seven iT-LBP cases (including five new cases that have not been reported in the literature) and 13 T-LBL cases were analysed. Clinical, morphological, immunophenotypic and molecular data were analysed. Immunohistochemical staining with LMO2 was performed on all iT-LBP and T-LBL cases. A review of five new iT-LBP cases showed similar morphological, immunophenotypic and molecular features to those of previously reported cases. All iT-LBP cases were negative for LMO2 (0/7), whereas 92% of T-LBL cases (12/13) expressed LMO2; the sensitivity was 92% (confidence interval 64-100%) and the specificity was 100% (confidence interval 59-100%).

CONCLUSION

We confirm previously published findings that iT-LBP cases show highly overlapping morphological and immunophenotypic features with T-LBL. Importantly, LMO2 expression is a sensitive and specific marker with which to rule out iT-LBP.

Scientific Advances and the Evolution of Diagnosis, Subclassification and Treatment of Lymphoma

The diagnosis of lymphoma has evolved tremendously over time. Initially, diagnosis of lymphoma was largely based on morphology alone. Over time, immunophenotyping using flow cytometry and immunohistochemistry, and then in situ hybridization, have contributed dramatically to the pathologist's ability to recognize, diagnose and subclassify lymphomas more precisely. In recent years, cytogenetic and molecular genetic techniques have developed that allow evaluation of abnormalities in lymphomas, leading to an understanding of their pathogenesis and opening the door to targeted therapies that will lead to better outcomes for lymphoma patients.

Sirolimus for the Treatment of Airway Obstruction due to Indolent T-Lymphoblastic Proliferation

Introduction

Indolent T-lymphoblastic proliferation (iT-LBP) is a rare nonmalignant entity that presents as a proliferation of T-lymphoblasts. We report a first such case with a recurrent laryngeal obstruction presentation that was successfully controlled with Sirolimus.

Case presentation

This is the case of a 29-year-old female who presented with a recurrent significant lymphoid hyperplasia in the adenoid and tongue base region as well as a right cervical lymph node. After repeated adenoidectomies and tonsillectomies, and based on pathological and clinical findings she was diagnosed with iT-LBP. Trials of radiotherapy and immunotherapy with cyclosporine and rituximab all failed to control the progression of the disease. Sirolimus was finally able to restrict the growth and improve her symptoms.

Conclusion

While It-LBP does not usually require treatment, it is important to report cases in which treatment was crucial for the survival of the patient, and the effective role of Sirolimus in doing so, without any major adverse effects.

Benign TdT-positive cells in pediatric and adult lymph nodes: a potential diagnostic pitfall

Benign terminal deoxynucleotidyl transferase (TdT)-positive cells have been documented in a variety of nonhematopoietic tissues. Scant data are, however, available on their presence in nonneoplastic lymph nodes. This study is aimed to (1) characterize the presence/distribution of benign TdT-positive cells in pediatric and adult reactive lymph nodes and (2) define the phenotype and nature of such elements. This retrospective study considered 141 reactive lymph nodes from pediatric and adult patients without history of neoplastic disease. TdT-positive cells were characterized by immunohistochemical and morphometric analyses, and their presence was correlated with the clinical-pathological features. The nature of TdT-positive cells was investigated by (1) double immunostaining for early lymphoid cell markers and (2) assessment of TdT expression in fetal lymph nodes. Sparse TdT-positive cells were documented in all pediatric cases and in most (76%) adult lymph nodes. TdT-positive cell density was higher in children than adults (15.9/mm² versus 8.6/mm²; P < .05). TdT positivity did not correlate with any clinical or histological parameter, and double immunostaining disclosed a phenotype compatible with early lymphoid precursors (positivity for CD34 and CD10, and variable expression of CD7). A very high TdT-positive cell density (802.4/mm²) was reported in all fetal lymph nodes. In conclusion, TdT-positive cells are a common finding in pediatric and adult lymph nodes. The interstitial distribution and low number of such cells allow for the differential diagnosis with precursor lymphoid neoplasms. The high density in fetal lymph nodes and the phenotype of such cells suggest their belonging to an immature lymphoid subset gradually decreasing with age.

Myasthenia Gravis Complicated with Peripheral T-cell Lymphoma, Not Otherwise Specified (PTCL-NOS), Following Thymectomy and Longstanding Tacrolimus Therapy

Myasthenia gravis (MG), a neuromuscular junction autoimmune disease, sometimes complicates second malignancies; however, T-cell lymphoproliferative disorders have rarely been reported. A 55-year-old man, who received oral tacrolimus and prednisolone for MG for 16 years after thymectomy, presented with left abdominal pain, lymphadenopathy, and splenomegaly. A lymph node biopsy revealed peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). This is the first report of oral tacrolimus leading to a T-cell lymphoproliferative disorder in patient without a history of transplantation. Physicians should be aware of the possibility of rare T-cell lymphoproliferative disorders, such as PTCL-NOS, occurring as complications in MG patients on immunosuppressive regimens after thymectomy.

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.

Flow cytometric characteristics of extrathymic thymocytes in adenoid tissue: A case report and comparison to normal thymus and thymoma

BACKGROUND

Normal thymocyte precursors in secondary lymphoid organs have previously been described. It is important to recognize normal thymocyte precursors by flow cytometry to differentiate them from T-cell lymphoblastic leukemia.

METHODS

A 3-year-old boy status 2 years post-allogenic cardiac transplant underwent adenoidectomy to exclude post-transplant lymphoproliferative disorder. Microscopic, immunohistochemical, and flow cytometry analyses of the adenoid were performed.

RESULTS

By flow cytometry, a population of CD45+(dim)/CD7+(bright)/CD3- cells were observed at 1.0% of lymphocytes. These cells expressed CD10, partial CD34, and exhibited acquisition of CD4 followed by CD8. Within the brighter CD45+ lymphocytes, a population of CD3-/CD4+/CD8+ thymocytes and a similarly sized population of CD4+/CD8+ cells exhibiting acquisition of low-density CD3 were identified. By immunostaining, clusters of TdT+/CD1a+/CD4+/CD8+ T-cells were identified in the interfollicular areas. Compared to normal thymus, thymocytes in the adenoid tissue lacked the classic CD4xCD8 winged differentiation profile but showed a normal early precursor pattern.

CONCLUSIONS

Thymocytes in adenoid show a similar differentiation pattern to thymus and thymoma. However, the classic winged pattern of common thymocyte differentiation may not be readily apparent in thymocytes differentiating outside of the thymus. Recognition of the early thymocyte precursor antigen acquisition profile can be crucial to correct interpretation. © 2017 International Clinical Cytometry Society.

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.

Nasopharyngeal tonsils (adenoids) contain extrathymic corticothymocytes

Adenoidal tissue (also known as nasopharyngeal tonsils) of 58% of humans in the pediatric age group contains immature T-lymphoid cells with the phenotype of thymocytes (TdT+,CD1abc+, cytoplasmic CD3+, coexpressing CD4 and CD8, lacking an Intraepithelial Lymphocyte-associated phenotype). The notable difference in comparison to palatine tonsils is the clustering in groups and sheets, comprising hundreds or thousands of cells (1.7%±0.2 of total T cells). The thymic epithelium is morphologically and phenotypically absent. Adenoids share with tonsils and lymph nodes the presence of immature B cell precursors (TdT+, CD1a-, Pax5+, Surrogate light chain±), however in these latter the presence of TdT+, CD1a+, Pax5- precursors is absent or limited to individual cells. Human adenoids are distinct among the Waldeyer's ring lymphoid tissue because of the known embryogenic derivation from the third pharyngeal pouch, from which the thymus develops; in addition, they may display phenotypic incomplete features of a vestigial thymus.

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).

The Hammersmith Hospital hematopathology case of the month: paraspinal B lymphoblastic lymphoma &#x2013; problems in diagnosis and initial indolent behavior

We describe a young man who presented with neurological signs and symptoms, and with a paraspinal soft tissue mass involving the vertebral body at T4. The patient was treated with dexamethasone prior to neurosurgical decompression and debulking. Biopsy showed features of a small B-cell lymphoma possibly of follicle center cell origin. The patient achieved complete remission with radiotherapy. However, he experienced relapse 10 months later with a soft tissue mass close to and involving the posteroinferior aspect of the sternum. Biopsy of the recurrent lesion showed features of B lymphoblastic leukemia/lymphoma. The first biopsy was revisited to demonstrate the lymphoblastic immunophenotype of the lesional cells. The 'indolent' appearance of the cells in the first biopsy was attributable to treatment with dexamethasone prior to the biopsy.

Hepatocellular carcinoma with immature T-cell (T-lymphoblastic) proliferation

Indolent T-lymphoblastic proliferation has been rarely reported in the upper aerodigestive tract. The lymphoid cells associated with this condition have the morphological and phenotypical features of immature thymocytes. However, their pathogenesis and biology are unknown. We present an unusual type of tumor infiltrating lymphocytes in a case with hepatocellular carcinoma, presumed to be a T-lymphoblastic proliferation. A 58-yr-old female patient presented with indigestion and a palpable epigastric mass. The abdominal computed tomography revealed a mass in the S6 region of the liver. A hepatic segmentectomy was performed. Microscopic examination showed dense isolated nests of monomorphic lymphoid cells within the tumor. Immunohistochemically, the lymphoid cells were positive for CD3, terminal deoxymucleotide transferase (TdT) and CD1a. In addition, they showed dual expression of CD4 and CD8. The polymerase chain reaction used to examine the T-cell antigen receptor gamma gene rearrangement showed polyclonal T-cell proliferation. This is the second case of hepatocellular carcinoma combined with indolent T-lymphoblastic proliferation identified by an unusual tumor infiltrating lymphocytes.

Follicular dendritic cell sarcoma with immature T-cell proliferation

Follicular dendritic cell sarcoma is characterized by proliferation of spindled to ovoid cells reminiscent of follicular dendritic cells. However, the association of follicular dendritic cell sarcoma with a dense infiltration of immature T cells has not hitherto been reported. We report an unusual case of follicular dendritic cell sarcoma of the mesentery with immature T-cell proliferation in a 68-year-old man. The infiltrating immature T cells demonstrated expression of CD3, CD1a, TdT, and coexpression of CD4 and CD8 by immunohistochemistry. In addition, the patient was subsequently diagnosed with myasthenia gravis and paraneoplastic pemphigus and died of distant metastasis within 2 years after initial diagnosis of follicular dendritic cell sarcoma. The aggressive clinical course of this case contrasts with the indolent course of follicular dendritic cell sarcomas, and thus, the prognostic implications of follicular dendritic cell sarcoma with immature T-cell proliferation require clarification. The complication of myasthenia gravis and paraneoplastic pemphigus may suggest that immature T-cell proliferation has an autoimmunity-related systemic influence.

Lymphoid progenitor cells in human tonsils

To investigate the occurrence of lymphoid progenitor cells in human tonsils, we studied tonsils from children and adults by immunohistochemistry by using a panel of antibodies to antigens associated with lymphoid progenitor cells, including terminal deoxynucleotidyl transferase (TdT), CD10 (CALLA), CD34, CD99 (p30/32mic2), and CD117 (c-kit), and compared them to reactive lymph nodes. Lymphoid progenitor cells, positive for TdT, CD10, and CD99, but not CD34 or CD117, were readily identified in tonsils from children and adults (TdT, 14 of 15; CD10, 15 of 15; CD99, 11 of 15), but were rarely present in lymph nodes (TdT, 1 of 8; CD10, 1 of 8; CD99, 0 of 8). Lymphoid progenitor cells in tonsils were localized to discrete foci at the periphery of lymphoid lobules adjacent to fibrous septae. Lymphoid progenitor cells are present in human tonsils, and the tonsils are a potential site of postnatal lymphopoiesis. The presence of lymphoid progenitor cells in human tonsils should not be confused with lymphoblastic lymphoma or leukemia.

Terminal deoxynucleotidyl transferase-positive cells in human tonsils

To study the possible cellular origin of recently recognized indolent terminal deoxynucleotidyl transferase (TdT)-positive T-lymphoblastic proliferations of the tonsils and oropharynx, we studied normal human tonsils for the presence of TdT-positive cells. TdT-positive cells were readily demonstrated in the tonsils from 15 children and adults by immunohistochemical staining. TdT-positive cells were distributed in discrete foci at the periphery of lobules of lymphoid tissue and adjacent to fibrous septa and had the morphologic features of small to medium-sized lymphocytes. Double-antibody staining indicated the TdT-positive cells had the phenotype of uncommitted early lymphoid precursors (CD3-, CD79a-, CD10-). Foci of TdT-positive cells were not identified in 6 reactive lymph nodes studied as controls. These studies indicate that tonsils, like bone marrow and thymus, are sites of lymphopoiesis. The presence of TdT-positive precursor cells in human tonsils may be a factor in the pathogenesis of recently described indolent T-lymphoblastic proliferations involving the tonsils and oropharynx. The presence of TdT-positive cells in human tonsils should not be misinterpreted as evidence of lymphoblastic lymphoma or leukemia.