Cell surface marker studies in a patient with cutaneous multilobated T-cell lymphoma

The phenotypic profile of atypical cells from a patient with cutaneous multilobated T-cell lymphoma was investigated using a multiparameter approach including evaluation of membrane markers, cytochemistry, and functional activity. Retroviral sequence restriction analysis was also used to investigate the presence of human T-cell leukaemia/lymphoma virus type I (HTLV-I) in atypical cells infiltrating the skin and in otherwise normal peripheral blood lymphocytes. The atypical cells appeared to belong to the T-lineage demonstrating OKT11 positivity, E-rosette formation, tartrate-sensitive acid phosphatase and beta-glucuronidase activity, and consistent negativity for cytoplasmic and/or surface monoclonal immunoglobulins. However, they failed to stain for other T-lymphocyte-associated antigens, such as those defined by OKT3, OKT4, OKT6, OKT8, OKT9, OKT10, Leu-2a and Leu-3a monoclonal antibodies, and did not express a definite alpha-naphthyl-acetate esterase pattern. Additional studies including phagocytosis tests and a series of monoclonal antibodies against phagocytic and natural killer cell associated antigens were all negative. No HTLV-I related sequences were found in either the cells infiltrating the skin or in circulating lymphocytes. To our knowledge, in previously reported cases of cutaneous multilobated cell lymphoma a clear T-lymphocyte phenotypic profile was demonstrated. Our present data indicate that this is not always necessarily the case. The peculiar phenotype we found might represent a transitional state between different T-cell subsets or an as yet unrecognized phenotype of a neoplastic T-lymphocyte which lacks a normal counterpart.