CD20 Positive T Cell Lymphoma Involvement of Skin

Abstract

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.

Keywords: CD20; T cell lymphoma; T cell receptor gene arrangement.

Fig. 1

Variably sized multiple crusted erythematous masses on the face, neck (A & B), and Left forearm (C).

Fig. 2

Diffuse and pandermal lymphocytic infiltration without epidermal involvement (A: H&E, ×40). The round tumor cells were small to medium sized with vesicular nuclei and prominent nucleoli and had a relatively monotonous appearance (B: H&E, ×400).

Fig. 3

Analysis of CD3 (A), CD4 (B), CD5 (C), UCHL-1 (D), CD20 (E), and for aCD79a (F) and bcl-2 (G) (immunoperoxidase stain, ×400).

Fig. 4

T cell receptor gamma gene rearrangement showed monoclononality at around 200 bp in the present and previous biopsy specimens (A, B), but immunoglobulin heavy chain gene rearrangement showed no monoclonality in either specimen (C, D).

Fig. 5

The immunophenotypic evaluation performed on a neck lymph node excised at the biopsy performed in 2005, was strongly positive for CD20 (A, ×400) and weakly reactive with UCHL-1 (B, ×400) in the cytoplasm of atypical lymphocytes.

Fig. 6

Immunophenotypic evaluation from a neck lymph node excised in 2005 was positive for CD3 (A, ×400) and CD4 (B, ×400) and negative for CD30 (C, ×400).

Fig. 7

The patient underwent ifosfamide, methotrexate, VP-16 (etoposide), and prednisolone chemotherapy and achieved partial remission with a decrease in mass size (A & B: face, neck, C: Left forearm).