CD5-CD56+ T-cell receptor silent peripheral T-cell lymphomas are natural killer cell lymphomas [see comments]

Abstract

Non-Hodgkin's lymphomas are divided into B- and T-cell neoplasms. The existence and the clinical relevance of lymphomas derived from the third lymphocyte lineage, ie, natural killer (NK) cells are still controversial. NK cells are lymphocytes that mediate cytotoxicity without prior sensitization. NK cells also have phenotypic and genotypic characteristics: they express the NK-related antigen CD56, T- cell markers such as CD2 and CD7, but do not express CD5 and T-cell receptor (TCR) proteins, and their TCR locus is not rearranged. Therefore, if NK cell lymphomas exist, they should express some T-cell markers, but not alpha beta or gamma delta TCR proteins. Such lymphomas are actually called TCR silent peripheral T cell lymphomas (PTCL). To detect and characterize NK cell lymphomas, we investigated the immunophenotype and immunogenotype of 35 patients with TCR silent PTCL. The first group included 16 patients with a lymphoma of CD5-CD56+ phenotype, which is identical to normal NK cells. These patients had either a nasal/nasopharyngeal lymphoma (11 cases) or a lymphoma with predominant non-nasal/non-nodal initial involvement (five cases). Eight of the nine cases for which immunogenotypic data were available lacked clonal rearrangement of the TCR gamma genes. Thus, these tumors are likely to be NK cell lymphomas. The second group of 15 cases had a CD5+ phenotype (14 were CD56-, and 1 was CD56+) and clonal rearrangement of TCR gamma genes, indicating that they were true PTCL with unproductive TCR rearrangement. The four remaining cases were CD5- CD56- lymphomas and disclosed either a clonal (two cases) or no clonal (two cases) rearrangements of the TCR gamma genes. Altogether these findings show that CD5-CD56+ so-called “TCR silent PTCL” bear the immunophenotype and immunogenotype of normal NK cells and display peculiar clinical features distinct from true PTCL.

Chromosome aberrations are restricted to the CD56+, CD3− tumour cell population in natural killer cell lymphomas: a combined immunophenotyping and FISH study

“…These results were in agreement with pathological and immunohistochemical findings (Sheridan et al, 1988;Emile et al, 1996;Jaffe, 1996). Although the morphology of tumour cells of NK-cell lymphomas is heterogenous, the tumour cells consistently express CD56, CD2, cytoplasmic CD3, but not surface CD3.…”

Lymphomatous features of aggressive NK cell leukaemia/lymphoma with massive necrosis, haemophagocytosis and EB virus infection

“…Previous reports have mentioned that few NK cell lymphoma cases included nodal involvement, 40,59 but our own showed nodal involvement in three of four patients. All cases with lymph node proliferation revealed a sinusoidal pattern of involvement.…”

Cutaneous presentation of nasal/nasal type T/NK cell lymphoma: clinicopathological findings of four cases

“…In addition, tumours were recognized in other extranodal sites, and the provisional term 'nasal-type' T/NK cell lymphoma was recommended. Recently, Emile et al 18 gave support to the concept that 'nasal and nasal-type T/NK cell lymphoma' is a distinct entity and provided further evidence for a derivation from NK cells, rather than from T cells. Macon et al 19 described six cases of lymphoma that they propose are derived from a unique subset of T cells, the NK-like or NK1þ T cells.…”

“…Interestingly, Jaffe et al 17 described rare cases that may present in the skin or soft tissue and relapse in the nose. In our review of the literature between 1983 and 1996, we found only 17 clear cases, 3,7,8,11,18,[21][22][23][24][25][26][27][28] of peripheral T-cell lymphoma with skin as well as nose metastasis. In six cases, 7,18,23,27,28 the lymphoma clearly proceeded from the skin.…”