Aberrant Immunophenotypic Expression of CD5 in a Case of B Acute Lymphoblastic Leukemia: A Case Report

HIF-1α regulates the expression of the non-conventional isoform of the cd5 gene in T cells under the hypoxic condition: A potential mechanism for CD5neg/low phenotype of infiltrating cells in solid tumors

CD5, a T-cell receptor (TCR) negative regulator, is reduced on the surface of CD8+ lymphocytes in the tumor microenvironment (TME). Reduced surface CD5 expression (sCD5) occurs due to the preferential transcription of HERV-E derived exon E1B, i.e., anon-conventional formofthe cd5gene instead of its conventional exon E1A. A tumor employs several mechanisms to evade anti-tumor response, and hypoxia is one such mechanism that prevails in the TME and modulates the infiltrated T lymphocytes. We identified hypoxia response elements (HREs) upstream of E1B. We showed binding of HIF-1α onto these HREs and increased E1B mRNA expression in hypoxic T cells. This results in decreased sCD5 expression and increased cytoplasmic accumulation in T cells. We also validated our study in a solid tumor, i.e., colorectal cancer (CRC) patient samples. This hypoxia-driven mechanism reduces the surface CD5 expression on infiltrated T-cells in solid tumors.

Aberrant expression of CD5 in a case of B acute lymphoblastic leukemia positive Philadelphia chromosome

INTRODUCTION

B acute lymphoblastic leukaemia (B-ALL) is a proliferation of hematopoietic precursor cells characterized by the expression of various B-cell antigens. Expression of T cell antigens has rarely been reported in B-ALL. We report the second case CD5+ (Cluster of differentiation 5) B-ALL associated with Philadelphia chromosome (Phi+).

OBSERVATION

A 38-year old male presented with anorexia and generalized weakness for the last ten days. Hemogram revealed bicytopenia and hyperleukocytosis made of 93% difficult to classify cells. A diagnosis of diffuse large B-cell lymphoma was suspected. An immunophenotyping on peripheral blood was performed. The panel for B- cell lineage chronic lymphoproliferative disorders (B-CLPD) was used. The dim expression of CD45 and the lack of surface immunoglobuline helped to exclude a CD5 expressing mature B cell neoplasm. Then, the diagnosis of ALL was confirmed by ALL panels. Karyotype showed a Phi+. Thus, a diagnosis of B-ALL with aberrant expression of CD5 and Phi+ was established. The patient received chemotherapy according to the modified group for research on adult acute lymphoblastic leukemia philadelphia positive 2005 protocol (GRAAPH 2005). A complete remission at the end of induction was obtained. The patient received consolidation and then, hematopoietic stem cell transplantation. The patient is in complete hematological remission till the date of submission of this report.

CONCLUSION

Aberrant expression of CD5 associated with Phi+ has rarely been reported in B cell lineage ALL and having a poor prognosis. Pathologists and clinicians should be aware of this entity to avoid confusion with other tumors.

B-Lymphoblastic Leukemia With Aberrant CD5 Expression

OBJECTIVES

B-acute lymphoblastic leukemia (B-ALL) is a neoplasm of precursor lymphoid cells committed to the B-lineage. Expression of CD5 is rare in B-ALL.

METHODS

We studied the clinicopathologic, immunophenotypic, and molecular genetic features of 10 cases of B-ALL with aberrant CD5 expression, and compared with CD5-B-ALL.

RESULTS

B-ALL with aberrant CD5 expression is rare and predominantly affects men. Patients with CD5+ B-ALL had shorter median overall survival (21 vs 45 months, P = .0003). Expression of CD5 imposed a challenge in the differential diagnoses between B-ALL and other CD5+ B-cell lymphomas with blastic morphology. Dim CD20 and CD45, lack of surface immunoglobulin, expression of CD34 and TdT, negative immunostain for cyclin D1, and absence of t(11;14)(q13;q32) support a diagnosis of B-ALL.

CONCLUSIONS

CD5 expression is rare in B-ALL and associated with poor clinical outcome. CD5+ B-ALL represents a distinct entity that needs to be considered in the differential diagnoses of CD5+ B-cell lymphoproliferative disorders.

Precursor B-lineage acute lymphoblastic leukemia patients with aberrant natural killer cell and T cell - lineage antigen expression: experience from a tertiary cancer care center

Introduction

Flow cytometric immunophenotyping (FCI) plays a major role in diagnosing hematologic malignancies. In patients diagnosed with precursor B-lineage acute lymphoblastic leukemia (B-ALL), expression of certain non-lineage/cross lineage antigens is of prognostic and cytogenetic relevance. There is a paucity of studies that have comprehensively analyzed the clinical and laboratory profiles of B-ALL patients showing aberrant T/natural killer (NK) cell antigen expression.

Materials and methods

This is a prospective study where 152 consecutive B-ALL patients were analyzed for aberrant expression of T/NK cell antigens (CD1a, CD5, CD4, CD7, CD8 and CD56) by FCI. The clinical and laboratory profile of these T/NK-cell antigen-expressing B-ALL patients was statistically analyzed against conventional B-ALL patients.

Results

In our B-ALL cohort, CD5, CD7 and CD56 expression were observed in one, six and nine patients, respectively. CD56-expressing B-ALL patients were predominantly children (89%) and presented as standard clinical risk (p = 0.010) disease with frequent ETV6-RUNX1 fusion (p = 0.021) positivity. On the contrary, CD7-expressing B-ALL patients were adolescent-young adult/adult-age skewed (83%) and had an adverse cytogenetic profile (p = 0.001), especially for the frequent presence of BCR-ABL1 fusion (p = 0.004) and KMT2A rearrangement (p = 0.045). CD7-expressing B-ALL patients had inferior event-free survival (p = 0.040) than their CD56-expressing counterparts, but there was no significant difference in the overall survival (p = 0.317).

Conclusion

In comparison to conventional B-ALL patients, there are significant differences in the age, cytogenetic profile and event-free survival of T/NK-cell antigen-expressing B-ALL patients.

Prognostic significance of aberrant CD5 expression in B-cell leukemia

Aberrant expression of CD5 (as a T-cell marker) is seen in some leukemia and lymphoma of B lineage origin. Given that the signaling resulting from the expression of this marker plays an essential role in the development of leukemia and lymphoma, evaluating the expression of this marker is of paramount importance. Therefore, our goal in this study was to investigate the prognostic importance of CD5 expression in B-cell leukemia and lymphoma. We evaluate CD5 expression in normal and leukemic B-cells by identifying relevant literature through a PubMed search (1998-2018) of English language papers using the terms: ‘CD5,’ ‘B-cell,’ ‘Leukemia,’ and ‘Lymphoma.’ We are doing this thorough comparison of results from CD5 positive and negative cases to make a correct decision about prognostic importance of CD5 expression in these malignancies. In a number of B-cell malignancies, CD5 is expressed in varying degrees. Due to the different origins and characteristics of these malignancies, the results of CD5 expression evaluations are heterogeneous and impossible to generalize. However, CD5 expression is sometimes associated with clinicopathologic findings, more invasive clinical course, and even resistance to treatment (specifically in DLBCL) among CD5- positive patients, which appears to be a function of CD5 signaling and its downstream factors such as STAT3. Depending on the type of malignancy, CD5 expression is associated with good or bad prognosis, which can be used as an auxiliary prognostic factor to assess the clinical course of B-cell malignancies. Moreover, the difference in expression levels of CD5 in a variety of B-cell malignancies allows for differential diagnosis of these malignancies, which can be helpful when diagnosis is difficult.

CD5 positive B-ALL, a uniquely aggressive subcategory of B-ALL? A case report and brief review of the literature

CD5 antigen expression in B-cell acute lymphoblastic leukemia (B-ALL) is exceptionally rare. There are six detailed case reports in the literature, with only 16 cases described. Case series analyzing the frequency of aberrant B-ALL immunophenotypes suggest that this variant may occur in as little as 2-4.5% of all B-ALL cases, with one series having no CD5⁺ positive cases. Herein we report a case of CD5⁺ B-ALL in a 15-year-old female, and review the previously reported cases. As limited information is available, more data from prospective clinical trials are required to determine whether CD5 positivity portends a poorer prognosis.

Diffuse large B-cell lymphoma, not otherwise specified presenting with bone and bone marrow involvement in the absence of lymphadenopathy

A 74-year-old woman visited our hospital because of right chest pain and fatigue. Laboratory examinations revealed pancytopenia and an elevated level of serum lactate dehydrogenase. Although bone lesions were detected by computed tomography, there was no lymphadenopathy. Blastoid cells were evident in the bone marrow. From the patient's medical history and results of immunohistological and chromosomal analysis, she was diagnosed as having diffuse large B-cell lymphoma, not otherwise specified. This form of presentation of diffuse large B-cell lymphoma is very rare, and emphasizes the need for careful evaluation of such cases, including bone marrow biopsy for accurate diagnosis.

CD5 Positive B Lymphoblastic Leukemia: Report of a Case with Review of Literature

We report a rare CD5 positive B cell acute lymphoblastic leukemia (B-ALL) with a review of the clinopathological features and prognosis of previously reported cases in the literature. The aberrant expression of CD 5 antigen is uncommon in B-ALL; the morphological differential diagnosis includes blastic mantle cell lymphoma, denovo CD5(+) diffuse large B cell lymphoma and secondary diffuse large cell lymphoma/Richter's transformation. CD5(+) B cell ALL is commonly reported in younger patients (<18 years). Though the expression of T cell antigens is reported to have poor prognosis, the experience with CD5(+) B-ALL is limited to draw any firm conclusion regarding its prognosis.