CD20+ T-cell Lymphoma

Abstract

Rare cases of CD20+ T-cell lymphoma (TCL) have been reported, but the clinicopathologic spectrum of this disorder is not known. We identified 9 cases of CD20+ TCL diagnosed at our institution and 26 additional cases through a search of the English language literature. Among current cases, there were 7 men (ages 71 to 81, median 75 y) and 2 women (ages 36 and 37 y). Five patients presented with predominantly nodal disease (localized in 3 and widespread in 2 cases) and 4 patients presented with purely extranodal disease involving the parotid glands, skin, or small intestine. CD20 was uniformly and strongly expressed in 5 cases and dimly expressed or present on a subset of neoplastic cells in 4 cases. The proportion of CD20+ T cells changed over time in 3 cases. Three cases fulfilled diagnostic criteria for clinicopathologically defined subtypes of TCL (2 mycosis fungoides; 1 enteropathy-type TCL), whereas 6 were peripheral TCL unspecified with variable cytomorphology, T-cell immunophenotype, and sites of involvement. In 8 of 9 cases, a clonal T-cell population was identified by molecular genetic analysis. Among 8 cases with clinical follow-up, 5 behaved aggressively with death from disease within 3 years of diagnosis in 4 cases (median survival: 11 mo, range: 1 to 35 mo), and recurrent disease at 10 months in 1 case; 1 patient died of an EBV+ B-cell lymphoma (BCL) 66 months after the original diagnosis; in the remaining 2 cases, patients were alive and undergoing treatment (follow-up: 4 and 18 mo). Historical cases showed similar clinicopathologic variability. CD20+ TCL is rare, and clinically and pathologically heterogeneous. When CD20 expression is present in TCL, it may be dimmer than that of normal B cells, suggesting neoplastic transformation of a normal CD20dim+ T-cell subset. Cases of CD20+ TCL in which the proportion of CD20+ cells changes over time may reflect aberrant expression of CD20, possibly as an activation marker, by neoplastic T cells. CD20+ TCL may cause diagnostic difficulty, particularly in cases that clinically and pathologically mimic BCL. Knowledge of the unusual phenomenon of CD20 expression in TCL, in conjunction with careful morphologic analysis, the use of a panel of antibodies, and molecular genetic studies, is important in avoiding a misdiagnosis of BCL.

B-cell Lymphomas With Concurrent IGH-BCL2 and MYC Rearrangements Are Aggressive Neoplasms With Clinical and Pathologic Features Distinct From Burkitt Lymphoma and Diffuse Large B-cell Lymphoma

“…Formalin- or B+-fixed, paraffin-embedded tissues from diagnostic biopsies of DHL cases and BL control cases were characterized by immunohistochemistry using previously described methods (44) with some or all of the following antibodies, if not already performed at the time of diagnosis: CD20 (L26 epitope, prediluted, Ventana Medical Systems, Tucson, AZ), CD79a (prediluted, Ventana), Pax5 (prediluted, Ventana), Bcl6 (1:10 dilution, Dako, Carpinteria, CA), CD10 (prediluted, Ventana), Bcl2 (clone 124, prediluted, Ventana), Mum1/IRF4 (1:20 dilution, Dako), Ki-67 (clone 30-9, prediluted, Ventana), terminal deoxynucleotidyl transferase (TdT, prediluted, Ventana). One case that lacked Bcl2 protein expression using clone 124 (targeting amino acids 41-54) was subsequently analyzed using clone C-2 (targeting amino acids 1-205) (Santa Cruz Biotechnology, Santa Cruz, CA).…”

“…One case that lacked Bcl2 protein expression using clone 124 (targeting amino acids 41-54) was subsequently analyzed using clone C-2 (targeting amino acids 1-205) (Santa Cruz Biotechnology, Santa Cruz, CA). In situ hybridization for EBV-encoded RNA (INFORM EBER Probe, Ventana) was performed as previously described (44). …”

CD20 Positive T Cell Lymphoma Involvement of Skin

“…Although the role of the CD20 antigen in T cell lymphomas has yet to be determined, the majority of CD20 positive T cell lymphoma cases have been reported as peripheral T cell lymphoma not otherwise specified11,21,22. We believe that a comprehensive study on the pathogenesis of CD20 positive T cell lymphoma and follow-up of more cases will result in a re-classification of this disease as a new disease entity.…”

“…CD20 positive T cell lymphoma is extremely rare and fewer than 40 cases have been reported11-15. A review of the literature revealed that the majority of the reported cases involved the lymph node and extranodal involvement was uncommon.…”

“…A review of the literature revealed that the majority of the reported cases involved the lymph node and extranodal involvement was uncommon. CD20 positive T cell lymphoma with only skin involvement accounts for 6/35 cases (17%) where the skin involvement manifests as cutaneous plaques, nodules, or erythematous patches11.…”