Clinicopathologic study of CD56 (NCAM)-positive angiocentric lymphoma occurring in sites other than the upper and lower respiratory tract.

The expression of the neural cell adhesion molecule (NCAM) (CD56, NKH-1) is a rare phenomenon in malignant lymphoma. Recently, several authors, including our group, described the clinicopathologic, phenotypic, and genotypic features of NCAM-positive tumors as a unique subgroup within a larger category of hematolymphoid malignancies. Ten cases of CD56+ angiocentric lymphoma occurring in sites other than the upper aerodigestive tract were studied for evaluating their characteristics. The disease occurred in six men and four women varying from 24 to 85 years (mean age, 53 years) who often exhibited a striking predilection for extranodal sites of involvement, such as the skin, gastrointestinal tract, and muscle, usually in the absence of peripheral lymphadenopathy. Although the cytologic appearances and immunophenotypic profile varied from case to case, these tumors often exhibited azurophilic granules, an angiocentric growth pattern, and surface CD3-, T-cell receptor (TCR) antigens-, and CD56+ phenotype without B-cell phenotype, except for a single case of CD3+, TCR alpha/beta+, and CD56+ phenotype. Genotype investigation exhibited germline configuration of the TCR beta and gamma chain genes and the immunoglobulin heavy chain gene in all five cases of surface CD3- phenotype examined, whereas the case of CD3+ phenotype showed rearrangement of TCR beta. They seem to constitute a distinct entity of the lineage spectrum spanning from natural killer (NK) cell to NK-like T cell.