CD4 and CD8 double-negative adult T-cell leukemia/lymphoma with monomorphic cells expressing CD99: A diagnostic challenge in a country non-endemic for human T-cell leukemia virus

An aggressive CD4- CD8- T-cell neoplasm in young English bulldogs

T-cell leukemia/lymphoma accounts for roughly 30% of all types of lymphoproliferative neoplasia in dogs. Two forms of T-cell lymphoma (T-zone and peripheral T-cell lymphoma) exhibit breed-specific predilections. During the course of routine immunophenotyping, we observed a breed-specific presentation of a unique form of T-cell leukaemia in young English bulldogs. To describe the clinical presentation and outcome of a novel T-cell leukaemia in English bulldogs and determine the frequency of this neoplasm in other breeds. The Clinical Hematopathology database, containing immunophenotyping data from peripheral blood of nearly 11 900 dogs, was queried for the phenotype observed in young English bulldogs: CD45⁺ CD4^- CD8^- CD5⁺ CD3⁺ class II major histocompatibility complex (MHC)-low T-cell leukaemia. Clinical presentation, treatment, and survival data were collected for a subset of cases. Fifty-five English bulldog cases and 64 cases of other breeds were identified. No other breed was represented by >5 cases. Complete medical records were obtained for 50 bulldogs. Median age at diagnosis was 3 years and 76% of cases were male. Median lymphocyte count was 44 286 lymphocytes/μl (range, 1800-317 684/μl) and lymphocytes were described as small to intermediate-sized. Many dogs were thrombocytopenic and had liver and spleen involvement, but not lymphadenopathy. Bulldogs that received multi-agent chemotherapy had longer median survival times (83 days) compared to dogs that received no treatment (6 days) or less aggressive therapy (15 days) (p = .001). Non-bulldogs had similar outcomes. CD4^- CD8^- class II MHC-low T-cell leukaemia has an aggressive clinical course and predilection for young English bulldogs. Breed-specific presentation suggests an underlying genetic cause.

Updates in lymph node and skin pathology of adult T-cell leukemia/lymphoma, biomarkers, and beyond

Adult T-cell leukemia/lymphoma (ATLL) is a mature T-cell lymphoproliferative disorder associated with the human T lymphotropic virus (HTLV-1) infection. ATLL predominantly affects individuals within HTLV-1 endemic areas such as Japan, areas of Africa, South America, and the Caribbean. HTLV-1 preferentially infects CD4+ T-cells, and several genetic hits must occur before ATLL develops. ATLL is classically divided into four clinical variants based on manifestations of disease: acute, chronic, lymphomatous, and smouldering. As of 2019, a new subtype has been described: lymphoma type of ATL, extranodal primary cutaneous. In this review, emphasis will be taken to describe the common clinicopathologic manifestations of the disease, advances in biomarker discovery, mutational landscape and targeted therapeutic approaches to treat this highly aggressive and frequently lethal type of T-cell lymphoma.

Adult T-type lymphoblastic lymphoma presenting as hypercalcemic crisis and aplastic anemia: a case report

BACKGROUND

Hypercalcemia and aplastic anemia are two uncommon presentations of non-Hodgkin lymphoma that potentially worsen the disease prognosis. Although hypercalcemia has been reported in the B-cell subtypes and some T-cell subtypes of non-Hodgkin lymphoma, it has not been described in T-cell lymphoblastic lymphoma. The same applies to aplastic anemia, which is also not described in T-type lymphomas.

CASE PRESENTATION

We report a case of a 52-year-old Cameroonian man with acute kidney injury who presented with confusion, abdominal pain, constipation, polyuria, polydipsia, calciphylaxis, enlarged lymph nodes, tachycardia, and a blood pressure of 170/88 mmHg. Laboratory investigations revealed hypercalcemia (total/ionized 199.5/101.75 mg/L), normal serum phosphorus (40.20 mg/L), and a low intact parathyroid hormone (9.70 pg/ml). Complete blood count revealed pancytopenia. Peripheral blood smear confirmed thrombocytopenia but showed neither blasts nor flower cells. Bone marrow aspirate revealed hypocellularity with no blasts or fibrosis. Lymph node biopsy was suggestive of T-cell precursor lymphoma. T-lymphoblastic lymphoma presenting with hypercalcemic crisis and aplastic anemia was diagnosed, and the patient received the cyclophosphamide-doxorubicin-vincristine-prednisone protocol of chemotherapy together with filgrastim and whole-blood transfusion for aplastic anemia. The short-term outcome was fatal, however.

CONCLUSIONS

Severe hypercalcemia and aplastic anemia are potential paraneoplastic syndromes of adult T-type lymphoblastic lymphoma, with fatal short-term outcome.

miR-664 negatively regulates PLP2 and promotes cell proliferation and invasion in T-cell acute lymphoblastic leukaemia

MicroRNAs (miRNAs) play important roles in the pathogenesis of many types of cancers by negatively regulating gene expression at posttranscriptional level. However, the role of microRNAs in leukaemia, particularly T-cell acute lymphoblastic leukaemia (T-ALL), has remained elusive. Here, we identified miR-664 and its predicted target gene PLP2 were differentially expressed in T-ALL using bioinformatics methods. In T-ALL cell lines, CCK-8 proliferation assay indicated that the cell proliferation was promoted by miR-664, while miR-664 inhibitor could significantly inhibited the proliferation. Moreover, migration and invasion assay showed that overexpression of miR-664 could significantly promoted the migration and invasion of T-ALL cells, whereas miR-664 inhibitor could reduce cell migration and invasion. luciferase assays confirmed that miR-664 directly bound to the 3'untranslated region of PLP2, and western blotting showed that miR-664 suppressed the expression of PLP2 at the protein levels. This study indicated that miR-664 negatively regulates PLP2 and promotes proliferation and invasion of T-ALL cell lines. Thus, miR-664 may represent a potential therapeutic target for T-ALL intervention.

Adult T-cell leukemia/lymphoma with an unusual CD1a positive phenotype

BACKGROUND

Acute T-cell leukemia lymphoma (ATLL) tumor cells generally express CD2/CD3/CD5, but lack CD7. These T cells are usually CD4+CD8- and strongly express CD25, although some variability in this basic pattern may be found. Here we report a case with a very unusual CD1a positive phenotype.

METHODS

Samples from peripheral blood, bone marrow aspirate, lymph node, and cerebrospinal fluid obtained from a 45-year-old male patient with a T-cell lymphoproliferative disorder were immunophenotyped by multiparametric flow cytometry. Analysis of HTLV-I genome integration in tumoral cells was performed by PCR.

RESULTS

Neoplastic T cells were cCD3, CD2/CD5/CD30/CD25, and CD1a positive, but CD3/CD7/CD4/CD8/CD34/CD10/TdT negative. Serology and integration of HTLV-I were positive.

CONCLUSION

To the best of our knowledge, CD1a expression has not been previously described in this entity. Its detection raised the differential diagnosis with acute T lymphoblastic leukemia. The rest of the phenotypic markers, the morphology of the neoplastic cells, and the demonstration of HTLV-I genome integration provided the final diagnosis.