A Case of CD20-Positive Adult T-cell Leukaemia/Lymphoma: Skin Biopsy and Analysis Contributed to Early Diagnosis and Improved Survival
Year: 2026
Type: article
Abstract: Dear Editor, Adult T-cell leukaemia/lymphoma (ATLL) is a refractory leukaemia of mature T-cells, associated with infection by human T-cell leukaemia virus type 1 (HTLV-1). HTLV-1 infection is endemic in southwestern Japan, particularly in Kyushu, as well as in the Caribbean islands, Central and South America, Central and southern Africa, aboriginal regions of Central Australia, parts of the Middle East and Melanesia, certain areas of Europe, and other smaller regions. The estimated lifetime risk of developing ATLL among HTLV-1 carriers is approximately 6.6% for men and 2.1% for women.[1] Typically, ATLL cells exhibit a helper-inducer T-cell phenotype, characterised by the expression of CD2+, CD3+, CD4+, CD8-, CD5+, and CD25+. However, in rare cases, variant phenotypes such as CD4-CD8-, CD4+ CD8+, or CD4-CD8+ have been observed. The CD20 antigen is one of the markers frequently utilised in the investigation of lymphomas. This marker has been considered specific to both benign and malignant B-cells and has been used to differentiate between T-cell and B-cell neoplasms. However, there have been rare cases reported in the literature where ATLL expresses CD20.[2-4] In this report, we present a case of CD20-positive ATLL diagnosed through a skin biopsy, along with a review of the relevant literature. A 76-year-old female patient presented to our hospital with indurated erythema accompanied by pruritus on the left posterior neck and trunk [Figure 1a]. Laboratory studies showed a WBC count 10,400/μL (3,300–8,600/μL), lymphocyte count 1144/μl(<4000/μL) with no atypical lymphocytes, LDH 377 U/L (120–220 U/L), corrected serum calcium (Ca)level 9.9 mg/dL (8.8–10.1 mg/dL), soluble interleukin-2 receptor 8720 U/ml (122–496 U/mL), and anti-HTLV-1 antibody positive. A skin biopsy was performed on the erythema with induration on the neck. Histopathologically, there was no epidermotropism, and the dermis showed diffuse infiltration by medium to large-sized lymphoid cells with nuclear pleomorphism [Figure 1b and c]. Immunohistochemical evaluation showed the neoplastic cells for CD3(+), CD4(+), CD8(-), CD20(+), CD79a (-), and PAX5(-) [Figure 1d-i]. By southern blot analysis, TCR gene rearrangement showed monoclonal rearrangements of the TCR β chains [Figure 1j] and monoclonal integration of HTLV-I provirus DNA into the leukaemia cell DNA was detected [Figure 1k]. Therefore, a diagnosis of CD20-positive ATLL was made. After that, PET-CT showed accumulation in the inguinal lymph nodes, and a biopsy was performed. Histopathological findings from the lymph node biopsy were consistent with CD20-positive ATLL, similar to the skin lesions. Based on the above findings, a diagnosis of lymphoma-type ATLL was made. The neoplastic cells were positive for the CCR4 antibody, and the patient underwent eight courses of combination chemotherapy, including mogamulizumab and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone); a partial response (PR) was achieved. Subsequently, the patient developed a new lesion on the skin of the left knee socket and was treated with lenalidomide. The patient died 16 months after the initial diagnosis.Figure 1: (a) The left posterior neck showed induration and erythematous plaques. (b) H and E stain at 40× magnification, diffuse lymphoid infiltrate in the superficial to deep dermis (c) H and E stain at 400× magnification, large to medium-sized, pleomorphic atypical lymphocytes diffusely infiltrate the dermis (Hematoxylin and eosin staining). Immunohistochemically, atypical lymphocytes were positive for (d) CD3, (e) CD4, and (f) CD20 and negative for (g) CD8, (h) CD79a, and (i) PAX-5. Southern blot analysis of the neoplastic cells demonstrated a clonal population of T-cells expressing the beta TCR clonality (j) (yellow arrow: left; negative control, right; this case) and HTLV-1 proviral DNA monoclonality (k) (yellow arrow: M; size marker, 1; positive control, 2; negative control, 3: this case)The literature review identified nine cases of CD20-positive ATLL, including our own case [Table 1].[2,5,6] The median age was 73 years, ranging from 45 to 90 years, with three males and six females. Biopsy was performed in eight cases, with only our case being definitively diagnosed through skin biopsy. In the remaining seven cases, the diagnosis was confirmed by lymph node biopsy. Extranodal involvement was observed in only two cases, both of which presented with skin lesions. According to the Shimoyama classification of ATLL, seven cases were of the lymphoma type, and two cases were of the acute type.[3]Table 1: Summary of current and reported cases of CD20-positive adult T-cell leukemia/lymphomaWe investigated the clinical course of six cases of CD20-positive ATLL of the lymphoma type and one case of the acute type, finding that the survival time ranged from 10 days to 16 months for the lymphoma type and was 11 days for the acute type [Table 1].[2,5,6] In general, the acute and lymphoma types show a median survival of 8.3 and 10.6 months, respectively.[4] Compared to the general prognosis of acute and lymphoma types, these cases had a poorer prognosis. The impact of CD20 expression on the prognosis of ATLL remains unclear. On the other hand, our patient had the longest survival time of 16 months. Two factors may have contributed to the patient’s long-term survival. First, the early diagnosis of ATL was made based on the analysis of cutaneous lesions. Second, treatment with mogamulizumab in combination with CHOP may have been effective. A recent phase 2 trial showed that mogamulizumab in combination with CHOP achieved a 1-year progression-free survival (PFS) rate of 36.2%, a complete response (CR) rate of 64.6%, and a median survival time (MST) of 1.6 years, all of which were higher than those observed in the historical control from the JCOG9801 trial (CHOP-14 arm: CR rate, 25%; 1-year PFS, 16%; MST, 10.9 months).[7] The mechanism for the expression of CD20 is still undetermined. One hypothesis is that a few CD20 dim T-cells exist among normal peripheral blood T-cells. The weak expression of CD20 in CD20-positive T-cell lymphomas suggests that these lymphomas may originate from the CD20 dim T-cell subset.[8] This possibility is also suggested for CD20-positive ATLL. An alternative hypothesis is that CD20 could serve as a marker for activation or proliferation when it appears on T-cells. Reduced surface expression of CD20 is associated with increased phosphorylation of internal residues of the molecule, a phenomenon observed in activated and proliferating B-cells.[9] To the best of our knowledge, the role of CD20 on human T-cells remains unexplored. However, in vitro studies have shown that monkey lymph node-derived T-cells temporarily express CD20 mRNA and surface CD20 when stimulated with mitogens and IL-2. Additionally, in monkeys infected with simian immunodeficiency virus, T-cells in enlarged lymph nodes display increased CD20 expression, indicating that T-cell activation may trigger CD20 expression.[10] In conclusion, we report the case of CD20-positive ATLL, diagnosed by skin biopsy and analysis of skin lesions. Although the number of reported cases of CD20-positive ATLL remains limited, it is recognized as having a poor prognosis. However, the prompt identification, biopsy, and analysis of skin lesions may lead to early diagnosis and treatment, potentially improving patient survival outcomes. Declaration of patient consent Since the patient had already passed away, informed consent was obtained from the patient’s son. The paper was written with the utmost care to ensure that the individual could not be identified. This matter was decided in consultation with the ethics committee of our institution. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Source: Indian Journal of Dermatology
Authors: Kosuke Mochida, Yukiyo Narita, Kyoko Nogami, Toshihiro Gi, Masaaki Sekine, Masahiro Amano
Institution: University of Miyazaki
Language: English
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: diamond
OpenAlex ID: W7141502003