Apoptosis and proliferation in subcutaneous panniculitis-like T-cell lymphoma

An update on genetic aberrations in T-cell neoplasms

T-cell neoplasms are a highly heterogeneous group of leukaemias and lymphomas that represent 10-15% of all lymphoid neoplasms. Traditionally, our understanding of T-cell leukaemias and lymphomas has lagged behind that of B-cell neoplasms, in part due to their rarity. However, recent advances in our understanding of T-cell differentiation, based on gene expression and mutation profiling and other high throughput methods, have better elucidated the pathogenetic mechanisms of T-cell leukaemias and lymphomas. In this review, we provide an overview of many of the molecular abnormalities that occur in various types of T-cell leukaemia and lymphoma. Much of this knowledge has been used to refine diagnostic criteria that has been included in the fifth edition of the World Health Organization. This knowledge is also being used to improve prognostication and identify novel therapeutic targets, and we expect this progress will continue, eventually resulting in improved outcomes for patients with T-cell leukaemias and lymphomas.

CD20-positive subcutaneous panniculitis-like T-cell lymphoma presenting as polycranial neuropathy: A CARE-compliant case report and literature review

BACKGROUND

Subcutaneous panniculitis-like T-cell lymphoma(SPTCL) is a very rare cytotoxic T-cell skin lymphoma involving subcutaneous tissue, and mainly affects young females. T-cell phenotype is characterized by CD3+, CD8+, and CD4-. SPTCT with polycranial neuropathy has rarely been described. SPTCL is believed to show an indolent clinical course unless patients develop haemophagocytic syndrome or sudden respiratory failure. Its treatment has not been established yet.

CASE PRESENTATION

We report a case of intractable SPTCT in a 66-year-old woman with multiple cranial nerve palsies and diabetes. She showed involvement of the bilateral facial nerve, left trigeminal nerve, left auditory nerve, and right oculomotor nerve. The single inconspicuous skin lesion in the trunk presented with an erythematous nodule with a diameter of <5 cm and a slightly pink infiltrated plaque. Electromyography revealed bilateral damage to the facial nerve. Differential immunohistochemical characteristics were observed. Immunohistochemistry demonstrated diffuse CD20 positivity. Cerebral spinal fluid analysis revealed elevated protein levels of 0.92 (0.15-0.45) g/L. Her condition regressed severely over time. She was treated with chemotherapy but died 10 months later, the probable cause of death was lung involvement.

CONCLUSION

The patient's involvement with the central nervous system may be associated with positivity for CD20. Molecular biomarkers may act as therapeutic targets for SPTCL.

Single-Cell RNA-seq Reveals Characteristics of Malignant Cells and Immune Microenvironment in Subcutaneous Panniculitis-Like T-Cell Lymphoma

Background

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a malignant primary T-cell lymphoma that is challenging to distinguish from autoimmune disorders and reactive panniculitides. Delay in diagnosis and a high misdiagnosis rate affect the prognosis and survival of patients. The difficulty of diagnosis is mainly due to an incomplete understanding of disease pathogenesis.

Methods

We performed single-cell RNA sequencing of matched subcutaneous lesion tissue, peripheral blood, and bone marrow from a patient with SPTCL, as well as peripheral blood, bone marrow, lymph node, and lung tissue samples from healthy donors as normal controls. We conducted cell clustering, gene expression program identification, gene differential expression analysis, and cell-cell interaction analysis to investigate the ecosystem of SPTCL.

Results

Based on gene expression profiles in a single-cell resolution, we identified and characterized the malignant cells and immune subsets from a patient with SPTCL. Our analysis showed that SPTCL malignant cells expressed a distinct gene signature, including chemokines families, cytotoxic proteins, T cell immune checkpoint molecules, and the immunoglobulin family. By comparing with normal T cells, we identified potential novel markers for SPTCL (e.g., CYTOR, CXCL13, VCAM1, and TIMD4) specifically differentially expressed in the malignant cells. We also found that macrophages and fibroblasts dominated the cell-cell communication landscape with the SPTCL malignant cells.

Conclusions

This work offers insight into the heterogeneity of subcutaneous panniculitis-like T-cell lymphoma, providing a better understanding of the transcription characteristics and immune microenvironment of this rare tumor.

High-throughput Sequencing of Subcutaneous Panniculitis-like T-Cell Lymphoma Reveals Candidate Pathogenic Mutations

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a malignant primary cutaneous T-cell lymphoma that is challenging to distinguish from other neoplastic and reactive panniculitides. In an attempt to identify somatic variants in SPTCL that may be diagnostically or therapeutically relevant, we performed both exome sequencing on paired tumor-normal samples and targeted sequencing of hematolymphoid-malignancy-associated genes on tumor biopsies. Exome sequencing was performed on skin biopsies from 4 cases of skin-limited SPTCL, 1 case of peripheral T-cell lymphoma, not otherwise specified with secondary involvement of the panniculus, and 2 cases of lupus panniculitis. This approach detected between 1 and 13 high-confidence somatic variants that were predicted to result in a protein alteration per case. Variants of interest identified include 1 missense mutation in ARID1B in 1 case of SPTCL. To detect variants that were present at a lower level, we used a more sensitive targeted panel to sequence 41 hematolymphoid-malignancy-associated genes. The targeted panel was applied to 2 of the biopsies that were evaluated by whole exome sequencing as well as 5 additional biopsies. Potentially pathogenic variants were identified in KMT2D and PLCG1 among others, but no gene was altered in >2 of the 7 cases sequenced. One variant that was notably absent from the cases sequences is RHOA G17V. Further work will be required to further elucidate the genetic abnormalities that lead to this rare lymphoma.

Primary Cutaneous Acral CD8+ T-Cell Lymphoma

Primary cutaneous acral CD8+ T-cell lymphoma is a new provisional entity in the 2016 revision of the World Health Organization classification of lymphoid neoplasms. This is a challenging diagnosis because of its rarity, as well as its morphologic and immunophenotypic overlap with other CD8+ cytotoxic lymphoid proliferations. Appropriate classification of this entity is crucial because of its indolent clinical behavior compared with other CD8+ T-cell lymphomas. Knowledge of the clinical setting, sites of involvement, and morphologic features can aid in correct diagnosis. Here, we review the clinical and pathologic features of primary cutaneous acral CD8+ T-cell lymphoma with an emphasis on the differential diagnosis among other C8+ T-cell lymphomas.

Primary T cell central nervous system lymphoblastic lymphoma in a child: case report and literature review

PURPOSE

Primary central nervous system lymphoma (PCNSL) of T cell origin is rare in pediatric patients. We report a case of T cell PCNSL in a 12-year-old boy and review the literature to highlight the importance of brain biopsy to definitively establish the diagnosis when PCNSL is suspected.

CASE REPORT

A 12-year-old boy presented with worsening left-sided weakness, nausea, vomiting, headache, blurred vision, and diplopia. Magnetic resonance imaging revealed right parietal gyral thickening with faint meningeal contrast enhancement. No clear diagnosis was identified after serum testing, cerebrospinal fluid analysis, and cerebral angiography. To establish the diagnosis definitively, a right craniotomy and open, frameless stereotactic biopsy were performed, which yielded the diagnosis of lymphoblastic T cell lymphoma.

CONCLUSIONS

PCNSL of T cell origin in children remains poorly studied, with only 18 detailed cases reported over the last three decades, including this case. Establishing a definitive diagnosis of PCNSL is challenging, and a brain biopsy is often required to obtain enough tissue for pathological analysis. Increasing awareness and identification of children diagnosed with T cell PCNSL is needed to better understand the molecular biology of this disease and develop more standardized treatment regimens.

CNS T-cell lymphoma: an under-recognized entity?

The incidence of CNS lymphoma has increased significantly in the past 30 years, primarily in the elderly and immunocompromised. While T-cell lymphomas comprise 15-20% of systemic lymphomas, they comprise less than 4% of primary CNS lymphomas, suggesting that they may be under-recognized compared to their systemic counterparts. To investigate this, we studied brain biopsies from three patients who were diagnosed with T-cell lymphoma confined to the brain. They had enhancing lesions by MRI, arising in the cerebellum and brainstem in one and temporal lobe in two. We compared these to biopsies from three patients who had reactive lymphoid infiltrates and who had clinical signs/symptoms and radiographic findings that were indistinguishable from the lymphoma group. Biopsies from both the lymphoma group and reactive group showed considerable cytomorphologic heterogeneity. Although one lymphoma case contained large atypical cells, the other two contained small, mature lymphocytes within a heterogeneous infiltrate of neoplastic and reactive inflammatory cells. Surface marker aberrancies were present in two lymphoma cases, but this alone could not reliably diagnose T-cell lymphoma. The proliferation index was not useful for differentiating lymphoma from reactive infiltrates. In five of the six cases the diagnosis was most influenced by clonality studies for T-cell receptor-gamma gene rearrangements. We conclude that because of the high degree of overlap in cytomorphologic and immunophenotypic features between T-cell lymphoma and reactive infiltrates, T-cell lymphoma may not be recognized unless studies for T-cell receptor gene rearrangements are performed for CNS lesions composed of a polymorphous but predominantly T-cell infiltrate.

Hepatosplenic and other gammadelta T-cell lymphomas

The 2005 Society for Hematopathology/European Association for Haematopathology Workshop session 11 was dedicated to hepatosplenic T-cell lymphoma (HSTCL). HSTCL is a rare aggressive type of extranodal lymphoma characterized by hepatosplenomegaly, bone marrow involvement, and peripheral blood cytopenias. HSTCL exhibits a distinctive pattern of infiltration; tumor cells preferentially infiltrate the sinusoids of the splenic red pulp, liver, and bone marrow. The tumor cells have a nonactivated cytotoxic T-cell immunophenotype and frequently carry a recurrent cytogenetic abnormality, isochromosome 7q. Most cases express the gammadelta T-cell receptor, but cases can have an alphabeta phenotype and are considered to be a variant of the disease. Although HSTCL is the prototype peripheral T-cell lymphoma expressing the gammadelta T-cell receptor, non-HSTCL proliferations of gammadelta T cells can involve other extranodal sites, mainly skin and mucosa. These gammadelta T-cell lymphomas display marked heterogeneity in clinical and histologic features. In contrast with HSTCL, non-HSTCL gammadelta T-cell lymphomas frequently have an activated cytotoxic phenotype and most likely are not a single disease entity.

The protean spectrum of non-Hodgkin lymphomas with prominent involvement of subcutaneous fat

BACKGROUND

Subcutaneous T-cell lymphoma (STCL) represents a controversial entity and a confused concept in the field of cutaneous T-cell lymphomas (CTCLs). Recently, alpha/beta+/CD8+ STCL has been recognized by the new World Health Organization (WHO)-European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphomas as a distinct entity in the group of CTCLs.

OBSERVATIONS

We reviewed a series of 53 biopsies from 26 patients (F : M = 19:7; median age: 48; range 18-87) of cutaneous B- and T-cell lymphomas characterized by prominent involvement of the subcutaneous tissue. We could classify our cases according to the following seven categories--(i) STCL: n = 16; (ii) extranodal NK/T-cell lymphoma, nasal type: n = 2; (iii) cutaneous gamma/delta T-cell lymphoma: n = 2; (iv) anaplastic CD30+ large T-cell lymphoma: n = 1; (v) diffuse large B-cell lymphoma, secondary cutaneous: n = 3; (vi) lymphoplasmacytic lymphoma, secondary cutaneous: n = 1; (vii) specific cutaneous manifestations of myelogenous leukemia: n = 1.

CONCLUSIONS

We demonstrated the protean nature of lymphomas with prominent involvement of the subcutaneous fat tissues. The term STCL should be restricted to a homogeneous group of cases characterized morphologically by an exclusive involvement of subcutaneous tissues, immunohistochemically by a T-cytotoxic alpha/beta phenotype, and biologically by a relatively good prognosis.

Immunophenotypic and molecular features, clinical outcomes, treatments, and prognostic factors associated with subcutaneous panniculitis-like T-cell lymphoma: a systematic analysis of 156 patients reported in the literature

BACKGROUND

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an uncommon type of skin lymphoma. The natural history, optimal treatment strategy, and prognostic factors associated with this malignancy are not well defined.

METHODS

The authors performed a systematic analysis of all patients with SPTCL reported on in the English-language medical literature, with emphasis on specific clinical features, experiences involving the use of radiotherapy and systemic agents, and prognostic factors predictive of treatment response and clinical outcome.

RESULTS

One hundred fifty-six patients with SPTCL were identified in the literature. Hemophagocytic syndrome (HPS) was a presenting feature in 37% of patients, and > 90% of patients required treatment at diagnosis. Prednisone was used frequently as initial therapy in patients who had less aggressive disease at presentation; however, durable complete remissions (CR) were infrequent. Anthracycline-based chemotherapy regimens were the most commonly used and most effective systemic treatment options, producing long-term CR in approximately 30% of patients. Among patients who received high-dose chemotherapy and stem cell transplantation (HDT-SCT) for refractory or recurrent disease, 92% achieved CR, with a median response duration of > or = 14 months. The presence of HPS at diagnosis and expression of the gamma/delta T-cell receptor (TCR) by tumor cells were associated with poor survival, whereas age was not. After a median follow-up of 24 months, 48% of patients died of disease. The median survival duration was 27 months.

CONCLUSIONS

SPTCL has an aggressive natural history. Nonetheless, a subgroup of patients with SPTCL can have long-term disease remission following anthracycline-based initial therapy or subsequent HDT-SCT. HPS and the TCR phenotype may be useful prognostic markers for patients with this malignancy.

Dysplasia and high proliferation rate are common in acute myeloid leukemia with inv(16)(p13q22)

Acute myeloid leukemia (AML) with inv(16)(p13q22), also known as M4Eo, is a distinct type of AML with a favorable prognosis associated with abnormal bone marrow eosinophils. We reviewed the morphologic findings of archival bone marrow specimens with M4Eo, specifically assessing for dysplasia, and performed immunohistochemical studies to assess the growth fraction using the MIB-1 (Ki-67) antibody. We also assessed the apoptotic rate by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labeling. All assessable cases had more than 10% dysplastic forms in at least 1 lineage. Seventeen cases had 10% or more dysplastic forms, and 3 cases had more than 50% dysplastic forms in at least 2 lineages. Immunoreactivity for Ki-67 was higher in M4Eo than in other AML types (P = .000). The apoptotic rate in M4Eo was similar to other AML types (P = .724). Our data show that dysplasia is a prominent feature, but not a prognostic indicator, in M4Eo. M4Eo is associated with a significantly higher proliferation rate than other AML types.