CD20 antigen may be expressed by reactive or lymphomatous cells of transformed mycosis fungoides: diagnostic and prognostic impact

Unveiling the Rarity: CD20 Expression in Mycosis Fungoides and Its Clinical Significance

ABSTRACT

Although CD20 expression is typically scarce in mycosis fungoides (MF), it is more commonly associated with T-cell lymphomas. Nevertheless, isolated instances of CD20-positive MF have been documented infrequently. Here, we present a unique case of CD20-positive MF in a 30-year-old man who manifested with a hypopigmented patch on the anterior chest. Histopathological examination revealed epidermotropic infiltrates of small- to medium-sized lymphocytes with hyperchromatic and cerebriform nuclei aligned along the basal and low-mid layers of the epidermis. Immunophenotypic analysis demonstrated neoplastic T cells expressing CD4+, CD8+, and CD3+ with the loss of CD7. Intriguingly, a notable subset of the neoplastic T cells exhibited CD20 expression. This case contributes to the sparse literature on CD20-positive MF and underscores its diagnostic and clinical ramifications. The role of B cells has been more thoroughly characterized in T-cell lymphomas other than MF. However, its significance in MF remains unclear due to the scarcity of reported cases. Some hypotheses propose that the B cells' expression might indicate immune dysregulation or complex interactions within the tumor microenvironment. Another perspective suggests it could signify a progression of the disease towards a more aggressive lymphoma phenotype. Further investigation and documentation of similar cases is imperative to elucidate the clinical features, prognosis, and optimal therapeutic strategies. The long-term prognosis and outcomes in patients with hypopigmented MF and CD20 positivity remain ambiguous, underscoring the necessity for continued research and scrutiny of analogous cases.

Concurrent Presentation of Mycosis Fungoides and Primary Cutaneous Marginal Zone LPD: Clinicopathological Study of 4 Cases and Literature Review

BACKGROUND

Mycosis fungoides is rarely associated to B-cell malignancies, and the few reported cases are mainly internal lymphomas involving secondarily the skin (ie, chronic lymphocytic leukemia).

OBJECTIVES

The aim of our study is to describe the clinical and histopathological features of 4 patients presenting with 2 concurrent primary cutaneous lymphomas and review the pertinent literature.

METHODS

We identified 4 cases of concurrent primary cutaneous lymphomas in our institutions. An extracutaneous lymphoma was ruled out on the basis of a complete work out. We performed a PubMed search to identify reported cases of primary cutaneous composite or concurrent lymphomas.

RESULTS

Eleven cases of primary cutaneous concurrent lymphomas have been described in the literature. Counting all together (our cases and the cases previously described in the literature), mycosis fungoides was the most frequent primary cutaneous T-cell lymphoma (TCL) (13/15), followed by 1 case of peripheral TCL-NOS and 1 case of subcutaneous panniculitis-like TCL. Regarding the associated primary cutaneous B-cell lymphomas, 8/15 cases consisted of low-grade B-cell lymphomas [that is, 5 marginal zone lymphoma (in the most recent classification reclassified as marginal zone lymphoproliferative disorder, MZLD, 2 follicular-center B-cell lymphoma (primary cutaneous follicle-center lymphoma) and 1 low-grade NOS B-cell lymphoma]; 4/15 were associated to Epstein-Barr virus; 1 case consisted of a methotrexate-associated lymphoproliferative disease, and 2 cases consisted of primary cutaneous diffuse large B-cell lymphoma-leg type.

CONCLUSIONS

Primary cutaneous concurrent lymphomas are exceptional. Clinicopathological correlation and a complete workout to reach the correct diagnosis may guide the appropriate treatment in each case.

The Transcription Factor Twist1 Has a Significant Role in Mycosis Fungoides (MF) Cell Biology: An RNA Sequencing Study of 40 MF Cases

The purpose of this RNA sequencing study was to investigate the biological mechanism underlying how the transcription factors (TFs) Twist1 and Zeb1 influence the prognosis of mycosis fungoides (MF). We used laser-captured microdissection to dissect malignant T-cells obtained from 40 skin biopsies from 40 MF patients with stage I-IV disease. Immunohistochemistry (IHC) was used to determinate the protein expression levels of Twist1 and Zeb1. Based on RNA sequencing, principal component analysis (PCA), differential expression (DE) analysis, ingenuity pathway analysis (IPA), and hub gene analysis were performed between the high and low Twist1 IHC expression cases. The DNA from 28 samples was used to analyze the TWIST1 promoter methylation level. In the PCA, Twist1 IHC expression seemed to classify cases into different groups. The DE analysis yielded 321 significant genes. In the IPA, 228 significant upstream regulators and 177 significant master regulators/causal networks were identified. In the hub gene analysis, 28 hub genes were found. The methylation level of TWIST1 promoter regions did not correlate with Twist1 protein expression. Zeb1 protein expression did not show any major correlation with global RNA expression in the PCA. Many of the observed genes and pathways associated with high Twist1 expression are known to be involved in immunoregulation, lymphocyte differentiation, and aggressive tumor biology. In conclusion, Twist1 might be an important regulator in the disease progression of MF.

Co-Expression of T- and B-Cell Markers in a Canine Intestinal Lymphoma: A Case Report

An 8-year-old female neutered Labrador retriever was presented for a second opinion consultation due to vomiting and lethargy, having failed to respond to symptomatic therapy. Blood analysis revealed hyperbilirubinemia and hypoalbuminemia, associated with hypocobalaminemia. An abdominal ultrasound identified diffused bowel thickening and hypoechoic hepatomegaly. An ultrasound-guided liver fine-needle aspiration was performed for cytology and also for cell block immunocytochemistry. Gastric and duodenal biopsies were collected by gastroduodenoscopy. Liver cytology showed numerous lymphocytes, suggesting lymphoma at the hepatic infiltration stage, and immunocytochemistry in the cell block of the hepatic aspirate indicated co-expression of CD3 and CD20 in the lymphoid cells present. The histopathology of gastric and duodenal biopsies supported the hypothesis of gastrointestinal lymphoma due to heavy lymphoid infiltration of the gastric epithelium and intestinal mucosa, including the villi. Concurrent immunohistochemistry was performed using CD3, CD20, PAX5, and CD79αcy antibodies. Immunomarking was positive for CD3 and CD20, which overlapped populations of lymphoid cells, and was negative for all other antibodies. In the clonality test, lymphocyte co-expression of CD3 and CD20 was confirmed by monoclonal rearrangement of T-cell gamma receptors. The final diagnosis was type 2 enteropathy-associated T-cell lymphoma with hepatic infiltration. Co-expression was examined in conjunction with the PARR result in the presence of T-cell monoclonal rearrangement.

Primary Cutaneous Anaplastic Large-Cell Lymphoma With Aberrant CD20 Expression: Case Report and Review of the Literature

ABSTRACT

Cutaneous CD20 + T-cell lymphomas are exceedingly rare. Differentiating cases of T-cell lymphoma with aberrant expression of the B-cell marker CD20 from B-cell lymphoma may be associated with misdiagnosis or delays in diagnosis. We report, to the authors' knowledge, the first case of CD20 + primary cutaneous anaplastic large-cell lymphoma and review the literature to characterize published cases of CD20 + cutaneous T-cell lymphoma (n = 40). There is no accepted explanation for this phenomenon; however, it is suspected that these cases may be due to neoplastic transformation of CD20 + T cells or that CD20 may represent a T-cell activation marker. Expression of CD20 may have clinical significance in prognostication and consideration of treatment options with anti-CD20 therapies such as rituximab.

Gamma-Delta and CD20 Mycosis Fungoides: Two Cases Uncovered by Broad-Spectrum Immunostaining

ABSTRACT

Mycosis fungoides (MF) expresses T-cell markers and the alpha-beta T-cell receptor (TCR) complex. Here, we describe a case of MF with dual expression of TCR delta and TCR beta and a case of MF expressing the B-cell marker CD20. Both anomalies were detected after we instituted a broad-spectrum immunostaining panel for cutaneous T-cell lymphomas. These findings suggest anomalous immunophenotypes may be more common in MF than previously appreciated. Histopathologists should be aware of unexpected malleability in the immunophenotype of MF to avoid confusion with other subtypes of cutaneous lymphoma. Further research into the prevalence and significance of CD20 and TCR-delta expression in MF is encouraged.

Targeted Deep Sequencing of Mycosis Fungoides Reveals Intracellular Signaling Pathways Associated with Aggressiveness and Large Cell Transformation

INTRODUCTION

Large-cell transformation (LCT) of mycosis fungoides (MF) has been associated with a higher risk of relapse and progression and, consequently, restricted prognosis. Its molecular pathogenesis has not been elucidated yet.

MATERIALS AND METHODS

In order to address molecular mechanisms of LCT, we performed hybrid capture panel-based sequencing of skin biopsies from 10 patients suffering from MF with LCT versus 17 patients without LCT including follow-up biopsies during clinical course, respectively (51 samples in total). The analyzed patients were attributed to three different groups based on the presence of LCT and clinical behavior.

RESULTS

While indolent MF cases without LCT did not show pathogenic driver mutations, a high rate of oncogenic alterations was detected in patients with LCT and aggressive clinical courses. Various genes of different oncogenic signaling pathways, including the MAPK and JAK-STAT signaling pathways, as well as epigenetic modifiers were affected. A high inter-individual and distinctive intra-individual mutation diversity was observed. Oncogenic RAS mutations were exclusively detected in patients with LCT.

CONCLUSION

Our data demonstrate that LCT transition of MF is associated with increased frequency of somatic mutations in cancer-associated genes. In particular, the activation of RAS signaling-together with epigenetic dysregulation-may crucially contribute to the molecular pathogenesis of the LCT phenotype, thus conveying its adverse clinical behavior.

Outcomes and prognostic factors in canine epitheliotropic and nonepitheliotropic cutaneous T-cell lymphomas

Canine cutaneous lymphoma is an uncommon lymphoma in dogs. Most canine cutaneous lymphoma cases have a T-cell origin. Canine cutaneous T-cell lymphoma (CTCL) is classified into epitheliotropic and nonepitheliotropic cutaneous lymphomas, and each type of lymphoma is subclassified into several histological subtypes. Limited information is available regarding the prognostic significance of clinical variables and histopathological subtypes in dogs with CTCL. This retrospective study aimed to investigate the influence of clinical variables and histopathological subtypes on the prognosis of dogs with CTCL. Forty-six dogs diagnosed with CTCL by histopathological examination were included. Histopathological specimens were reexamined and classified into CTCL subtypes. The influence of the type of skin lesion, histopathological subtype, haematological examination results and treatment response on the overall survival time (OS) was examined. Thirty-one dogs were diagnosed with epitheliotropic CTCL (mycosis fungoides in 28 dogs; pagetoid reticulosis in 3 dogs) and 15 dogs were diagnosed with nonepitheliotropic CTCL (anaplastic large T-cell lymphoma in 6 dogs; peripheral T-cell lymphoma, not otherwise specified, in 9 dogs). The OS of dogs diagnosed with epitheliotropic CTCL (141 days) was significantly shorter than that of dogs diagnosed with nonepitheliotropic CTCL (374 days). As clinical variables, the presence of neoplastic lymphocytes in peripheral blood, thrombocytopenia and initial chemotherapeutic response was related to prognosis. Our results demonstrated that histopathological subtype and several clinical variables were found to influence the prognosis of dogs with CTCL.

Primary Cutaneous CD4+ Small/Medium T-Cell Lymphoproliferative Disorders: A Clinical, Pathologic, and Molecular Study of 60 Cases Presenting With a Single Lesion: A Multicenter Study of the French Cutaneous Lymphoma Study Group

Primary cutaneous CD4 small/medium T-cell lymphoproliferative disorder (PCSMLPD) is a recently recognized entity in the 2017 World Health Organization (WHO) classification. It belongs to the T-follicular helper (TFH) lymphoproliferations. The clinical, pathologic, and molecular features of this localized disease are underresearched. We conducted a retrospective multicentric study of 60 patients with a PCSMLPD that presented as a single cutaneous lesion. Clinical, pathologic, and targeted molecular analyses were performed. PCSMLPD presented mostly as a nodule (45%), located on the head and neck area (50%) in adults (mean age: 59 y [43.3 to 75.2]). All patients had an indolent disease course, either at initial staging or during follow-up (mean: 16.6 mo [1.3 to 31.9]). Spontaneous regression was reported in 31.9% of cases. The infiltrates were most often nodular and/or diffuse, expanding in the whole dermis (78%, Pattern 1), rather than subepidermal band-like in the superficial dermis (22%, Pattern 2). Epidermotropism, folliculotropism, and capillary hyperplasia were common. The expression of TFH lineage markers was more extensive in lesions with Pattern 2, but a substantial B-cell infiltrate was seen in both types of lesions. A clonal rearrangement of the TCR genes was identified in 68% of cases. One sample of the 13 tested revealed a mutation in the DNMT3A gene among the 9 genes studied (TET2, DNMT3A, IDH2, RHOA, SETD2, PLCG1, STAT3, STAT5B, and CD28). PCSMLPD follows a benign clinical course and can spontaneously regress after biopsy. Although PCSMLPD expresses TFH lineage markers, mutations usually found in angioimmunoblastic T-cell lymphomas are uncommon.

CD20-positive extranodal NK/T cell lymphoma: clinicopathologic and prognostic features

Extranodal natural killer (NK)/T cell lymphoma (ENKTCL) with aberrant CD20 expression is extremely rare. Here, we describe the clinicopathologic features of 11 CD20-positive ENKTCLs from three institutions in China along with a literature review. Membranous expression of CD20 was identified in 1.29% (11/851) of ENKTCLs. CD20-positive ENKTCLs primarily occurred in extra-nasal sites (72.2%, 13/18) rather than in the nasal cavity (27.8%, 5/18). Most evaluated patients (71.4%, 10/14) presented ENKTCL at advanced stage IV. The percentage of CD20-positive tumor cells ranged from 20 to 90%, and the CD20 staining intensity was dimmer in tumor cells than in normal B cells. Among four cases with multiple biopsies, three cases showed discordant expression of CD20 between the disseminated and primary lesions. All evaluated cases were negative for other B cell markers, including PAX5, CD79a, and CD19, except for one case that showed focally positive for CD79a. Patients with CD20-positive ENKTCL more frequently had advanced diseases (stage III/IV: 70% vs 17%, p = 0.001), with older age (median age at diagnosis: 60 years vs. 43.5 years, p = 0.006) and had inferior outcome (median survival: 18.7 moths vs 36.0 moths, p = 0.017) compared with CD20-negative cases. Four nonsynonymous single nucleotide variants (C > T) and one stop-gain mutation (C > T) in the exonic region of CD20 gene (MS4A1) were detected in one of seven cases with target region next-generation sequencing. Thus, ENKTCL with aberrant CD20 expression is rare, tends to occur in older patients, and is characterized by a highly aggressive clinical course and poor outcomes. The mechanism underlying the expression of CD20 in ENKTC still remains unknown.

Another window into tumor microenvironment: a case of Β-cell rich folliculotropic mycosis fungoides responding to rituximab

The role of tumor infiltrating immune cells in cancer development and progression is a new, promising field in oncological research. An increasing number of novel anti-cancer agents are focussing on the tumor microenvironment. Various studies have reported on B-cell infiltrates in mycosis fungoides (MF), but despite the substantial volume of interesting findings, solid evidence regarding their specific role in cancer is still vague. We present a case of tumor stage  MF responding to rituximab. We support the hypothesis that lymphoma-infltrating B-cells have a significant impact on cutaneous lymphoma course and seem to be both an important and effective therapeutic target. The reduction of B-cell population led to disease's overall remission, probably by restoring patient's immunologic tumor control.

Prevalence of CD20+ cutaneous epitheliotropic T-cell lymphoma in dogs: a retrospective analysis of 24 cases (2011-2018) in the USA

BACKGROUND

Limited information is known about the baseline frequency of canine CD20 positive (⁺ ) cutaneous epitheliotropic T-cell lymphoma. A single canine case report has been published.

OBJECTIVES

To characterize the baseline frequency of CD20⁺ staining in cases of canine cutaneous epitheliotropic T-cell lymphoma; to assess its values as a prognostic indicator.

ANIMALS

Skin biopsies from 24 client-owned animals diagnosed with cutaneous epitheliotropic lymphoma were assessed.

METHODS AND MATERIALS

A retrospective review of medical records from 2011 to 2018. Clinical histories and previous histological and immunohistochemical slides were collected from 24 dogs and additional immunohistochemical staining was performed as needed to assess cases of cutaneous epitheliotropic T-cell lymphoma for CD3, CD20, CD79a and PAX5 staining characteristics. Staining characteristics were assessed for their statistical relationship to median survival time.

RESULTS

Overall median survival time was 189 days following the onset of clinical signs and 99 days following definitive diagnosis; 54% of cases had CD20⁺ staining. There was no statistically significant correlation between staining characteristics and median survival time from onset of signs (P = 0.54) or from diagnosis (P = 0.61).

CONCLUSIONS AND CLINICAL SIGNIFICANCE

Canine cutaneous epitheliotropic lymphoma has a higher instance of CD20 positivity than documented previously. This indicates that CD20 staining may be unsuitable to differentiate T-cell and B-cell cutaneous epitheliotropic lymphoma. This also may have therapeutic implications with the advent of canine CD20 monoclonal antibody therapies.

Primary Cutaneous Composite Lymphomas

Composite lymphomas have been defined as 2 distinct subtypes of lymphoma occurring at a single anatomic site. Composite lymphomas limited to the skin are a rare occurrence and pose a unique challenge. Many reported cases within the skin are combined B-cell and T-cell lymphomas, typically mycosis fungoides and a low-grade B-cell lymphoma. These cases are challenging to recognize because lymphoid infiltrates within the skin often include a mixed population of B cells and T cells. In particular, reactive lymphoid proliferations (pseudolymphomas), primary cutaneous low-grade B-cell lymphomas, and primary cutaneous CD4+ T-cell lymphoproliferative disorder may show nearly equal numbers of B cells and T cells. In order to exclude these possibilities, overwhelming evidence in support of each lymphoma is helpful, including abnormal architecture, cytology, and immunophenotype, as well as molecular genetic evidence of clonality.

CD3 and CD20 co-expression in a case of canine peripheral T-cell lymphoma with prominent cardiac and peripheral nerve involvement

An 8-y 9-mo-old male Pug dog was presented because of anorexia, hindlimb ataxia, vomiting, and progressive weight loss. Clinical examinations revealed atrophic hindlimb muscles with decreased postural reaction, enlargement of the cardiac silhouette and megaesophagus on radiograph, and reduced cardiac contractility on ultrasonography. The dog died 10 d after the initial examination, and an autopsy was performed. Grossly, the heart was enlarged, with multifocal-to-coalescing extensive plaque-like areas of discoloration on the epicardial surface. On cross-section, the ventricles were moderately dilated, and discoloration extended into the myocardium. Peripheral lymph nodes were of normal size. Histologically, atypical lymphoid cells replaced the myocardium and also extensively infiltrated peripheral nerve bundles in various organs. With immunohistochemistry, the neoplastic cells exhibited strong immunoreactivity for CD3 and CD20, and were negative for CD8, granzyme B, CD79α, and Pax5. Double-label immunofluorescence confirmed co-expression of CD3 and CD20 by the neoplastic cells. Molecular clonality analysis presented a clonal T-cell receptor gamma gene rearrangement. The case was diagnosed as a CD3+/CD20+ peripheral T-cell lymphoma with prominent cardiac and peripheral nerve involvement, indicating neurolymphomatosis.

Flow Cytometric Analysis of T, B, and NK Cells Antigens in Patients with Mycosis Fungoides

We retrospectively analyzed the clinicopathological correlation and prognostic value of cell surface antigens expressed by peripheral blood mononuclear cells in patients with mycosis fungoides (MF). 121 consecutive MF patients were included in this study. All patients had peripheral blood flow cytometry as part of their first visit. TNMB and histopathological staging of the cases were retrospectively performed in accordance with International Society for Cutaneous Lymphomas/European Organization of Research and Treatment of Cancer (ISCL/EORTC) criteria at the time of flow cytometry sampling. To determine prognostic value of cell surface antigens, cases were divided into two groups as stable and progressive disease. 17 flow cytometric analyses of 17 parapsoriasis (PP) and 11 analyses of 11 benign erythrodermic patients were included as control groups. Fluorescent labeled monoclonal antibodies were used to detect cell surface antigens: T cells (CD3(+), CD4(+), CD8(+), TCRαβ(+), TCRγδ(+), CD7(+), CD4(+)CD7(+), CD4(+)CD7(-), and CD71(+)), B cells (HLA-DR(+), CD19(+), and HLA-DR(+)CD19(+)), NKT cells (CD3(+)CD16(+)CD56(+)), and NK cells (CD3(-)CD16(+)CD56(+)). The mean value of all cell surface antigens was not statistically significant between parapsoriasis and MF groups. Along with an increase in cases of MF stage statistically significant difference was found between the mean values of cell surface antigens. Flow cytometric analysis of peripheral blood cell surface antigens in patients with mycosis fungoides may contribute to predicting disease stage and progression.

CD3 and CD20 Coexpression in a Case of Canine Cutaneous Epitheliotropic T-Cell Lymphoma (Mycosis Fungoides)

A 14-year-old female spayed Dachshund was presented with generalized scaling, erythema, pruritus, poor quality of hair coat, and progressive weight loss. Cutaneous epitheliotropic T-cell lymphoma (CETCL) was suspected. Skin biopsies were suggestive of CETCL. However, immunohistochemistry revealed the presence of numerous CD20+ and CD3+ cells. Clonality assay demonstrated a clonal T-cell receptor gamma rearrangement and a polyclonal IgH gene rearrangement. Double-label immunofluorescence confirmed coexpression of CD3 and CD20 by neoplastic cells. By double immunohistochemistry, neoplastic cells were CD3+ and PAX5–. The results are compatible with a CD3+, CD20+ CETCL. Coexpression of CD20 and CD3 has been recognized in peripheral T-cell lymphomas. Although documented in human CETCL, it has not been reported in canine CETCL. The pathogenetic basis of CD20 expression in mycosis fungoides is explored.

Phase II Investigator-Initiated Study of Brentuximab Vedotin in Mycosis Fungoides and Sézary Syndrome With Variable CD30 Expression Level: A Multi-Institution Collaborative Project

PURPOSE

In contrast to Hodgkin lymphoma and systemic anaplastic large-cell lymphoma, CD30 expression of malignant lymphocytes in mycosis fungoides (MF) and Sézary syndrome (SS) is quite variable. Clinical activity and safety of brentuximab vedotin, a CD30 targeting antibody-drug conjugate, was evaluated in MF and SS. Tissue and blood biomarkers of clinical response were explored.

PATIENTS AND METHODS

In this phase II study, patients with MF or SS with negligible to 100% CD30 expression levels were treated with brentuximab vedotin (1.8 mg/kg) every 3 weeks for a maximum of sixteen doses. The primary end point was overall global response rate. Secondary end points included correlation of tissue CD30 expression level with clinical response, time to response, duration of response, progression-free and event-free survivals, and safety.

RESULTS

Of the 32 patients enrolled and treated, 30 patients had available efficacy evaluations. Objective global response was observed in 21 (70%) of 30 patients (90% CI, 53% to 83%). CD30 expression assessed by immunohistochemistry was highly variable, with a median CD30max of 13% (range, 0% to 100%). Those with <5% CD30 expression had a lower likelihood of global response than did those with 5% or greater CD30 expression (P < .005). CD163 positive tumor-associated macrophages, many of which coexpress CD30, were abundant in tissue. Peripheral neuropathy was the most common adverse event.

CONCLUSION

Brentuximab vedotin demonstrated significant clinical activity in treatment-refractory or advanced MF or SS with a wide range of CD30 expression levels. Additional biomarker studies may help optimize rational design of combination therapies with brentuximab vedotin.

CD8-positive peripheral T-cell lymphoma with aberrant expression of CD20 and concurrent in situ follicular lymphoma

A case of a 78-year-old woman with a CD8-positive peripheral T-cell lymphoma with aberrant expression of CD20 associated with follicular lymphoma in situ (FLIS) is reported. The neoplasm presented initially as cutaneous macules, papules, plaques and nodules. A skin biopsy was performed and the diagnosis of peripheral T-cell lymphoma (PTCl) with aberrant expression of CD20 was made. The staging procedures included an excisional inguinal lymph node biopsy that showed findings similar to those of the previous diagnosis. In addition, FLIS was identified. The clinicopathologic features of PTCLs with aberrant CD20 expression involving the skin as well as this uncommon association are reviewed.