CD20-positive T-cell lymphoma with indolent clinical behaviour

CD20-positive NK/T-cell lymphoma with indolent clinical course: report of case and review of literature

Abstract

CD20-positive T-cell lymphoma is extremely rare and only two cases of CD20-positive NK/T-cell lymphoma with aggressive clinical courses have been described in the literature. We present a case of unusual NK/T-cell lymphoma with CD20 expression in nasal cavity occurring in an elder female patient. The patient had presented with left nasal cavity nodule for 10 years. CT scan revealed a mass was located at the left anterior nasal cavity and was observed to extend into the ethmoid sinus. There was no regional lymph node involvement. Biopsy was performed and microscopical inspection revealed the lesion was composed of small- to middle-size atypical lymphoid cell, histiocytes, eosinophils, and neutrophils. The lymphoid cells were strongly immunoreactive to CD3, CD20, CD56, TIA-1 and granzyme-B. The Epstein-Barr virus genomes were also found in tumor cells by in situ hybridization. By genetic analysis, however, no clonal rearrangement of the T cell receptor-γ genes (TCRG), or the immunoglobulin heavy chain (IgH) gene was found. A diagnosis of CD20-positive extranodal NK/T-cell lymphoma, nasal type was made. The patient refused chemotherapy, and had been only on regular follow-up for 6 months. There was no sign of enlargement of tumor and extra-nasal dissemination by whole body positron emission tomography/computed tomography (PET/CT) study. The accurate diagnosis of NK/T-cell lymphoma with CD20 expression is important, but the indolent behavior of the present case is more unusual. A long-term follow-up is suggested to be performed to inspect the progression for this tumor.

Virtual slides

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CD20 Positive T Cell Lymphoma Involvement of Skin

CD20 positive T cell lymphoma is a rare condition that is associated with the coexpressions of CD20 and T cell markers, such as, CD3, CD5, or UCHL-1. Positivity for CD20 in this tumor represents an aberrant immunophenotype, but the presence of monoclonal T cell receptor (TCR) gene rearrangements and negativity for immunoglobulin heavy chain gene rearrangement indicate that this tumor is a T cell lymphoma. The majority of cases of CD20 positive T cell lymphoma have been reported as immature peripheral T cell lymphoma not otherwise specified. However, we believe that this disease is likely to be re-listed as a new disease entity after its pathogenesis has been elucidated and more cases have been evaluated. Here, we present a case of peripheral T cell lymphoma coexpressing CD20 and T cell markers with a demonstrable TCR gene rearrangement, in a patient who had been misdiagnosed as having B cell type lymphoma 4 years previously. We hypothesize that in this case initially circulating normal CD20+ T cell subsets underwent neoplastic transformation and CD20 positive T cell lymphoma subsequently developed in the lymph node, and then recurred in the skin due to systemic disease or metastasized from the nodal disease.