Indolent T-lymphoblastic proliferation associated with low grade follicular dendritic cell sarcoma and Castleman disease

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.

Case report: The stroma-rich variant of Castleman’s disease of hyaline-vascular type with atypical stromal cell proliferation and malignant potential: An exceptional rare case occurred in mediastinal lymph node

The stroma-rich variant of Castleman disease of hyaline-vascular type (SR-HVCD) is characterized by interfollicular proliferation of the fibroblastic, myofibroblastic, and/or histiocytic-derived stromal cells, occurred in a background of Castleman disease of hyaline-vascular type (HVCD). It has been considered as a hyperplastic disorder by far. Herein, we presented a case of a 40-year-old male suffering from an occupation in the right middle mediastinum. Microscopically, the lesion was characterized by atretic lymphoid follicles and overgrowth of the interfollicular spindle-shaped cells. Those spindle cells were histologically bland in some areas, while exhibited notable cellular atypia and focal necrosis in other areas. SMA and CD68 were immunostained with a subset of the spindle cells in both areas, whereas p53 staining was only perceived in areas with markedly cellular atypia. In addition, indolent T-lymphoblastic proliferation (iT-LBP) was present inside the lesion. The patient developed multiple sites metastases 4 months after surgery, and succumbed to the disease at 7 months. Our case demonstrates for the first time that SR-HVCD have a tumorigenesis potential rather than a simple hyperplastic process. Such disorder should be carefully evaluated to avoid underdiagnosis.

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).

Histiocytic and Dendritic Cell Neoplasms

Histiocytic and dendritic cell neoplasms are very rare, belonging to a group that share morphologic, immunophenotypic, and ultrastructural characteristics of mature histiocytic/dendritic neoplasms. Histiocytic and dendritic cell neoplasms may arise de novo or in association with B-cell, T-cell, or myeloid neoplasms. Recent molecular findings, particularly the discoveries of the mutations in the RAS-RAF-MEK-ERK pathway, have greatly advanced the diagnosis and treatment options. Histiocytic and dendritic cell neoplasms may closely resemble each other, non-hematopoietic neoplasms, and even reactive processes. Therefore, it is essential to understand the clinicopathologic characteristics, differential diagnoses, and pitfalls of each entity.

Castleman Disease

Castleman disease (CD) is divided clinically into unicentric or multicentric type. Pathologically, CD is divided into hyaline-vascular and plasma cell variants. Unicentric CD is most common, about 75% of these cases are hyaline-vascular variant, and surgical excision is often curative. In contrast, there are a number of types of multicentric CD including HHV8-associated, idiopathic, and a subset of cases that arise in association with POEMS syndrome. Therapy is required for most patients with multicentric CD, but there is no consensus approach currently. As is evidence, the designation Castleman disease encompasses a heterogeneous group of diseases of varied pathogenesis and which require different therapies.

Distinguishing thymoma from T-lymphoblastic leukaemia/lymphoma: a case-based evaluation

T-lymphoblastic lymphoma and thymoma are distinct primary mediastinal neoplasms that can have similar clinical presentations and overlapping histological features. Microscopic distinction is occasionally difficult because the immature lymphocytes associated with thymoma may resemble T-lymphoblastic leukaemia/lymphoma cells, morphologically and immunohistochemically. An accurate diagnosis assumes particular importance since the treatment approaches for these two entities differ considerably. Multimodality diagnostic approaches incorporating histological, flow cytometry immunophenotypic' and molecular approaches are required. In this article, we describe four patients, each presenting with a mediastinal tumour in different clinicopathological settings. A detailed report of each case will follow, illustrating the challenges involved in the diagnosis in patients with these mediastinal neoplasms.