Cutaneous T-cell lymphoma, multilobated type, expressing membrane differentiation antigens of precursor T-lymphocytes.

Monoclonal antibodies to human T-cell membrane antigens were used to evaluate the immunological phenotype of the tumour cells in two cases of a recently described cutaneous T-cell lymphoma of 'multilobated' type. In one case the distinctive abnormal blast cells expressed positivity for OKT6, anti-HTAI, OKT4 and Leu-3a, and showed binding capacity for peanut agglutinin (PNA). These are properties normally displayed by immature cortical thymocytes. The antigen expression of the abnormal blast cells in the other case was OKT3, Leu-I, OKT4, Leu-3a in the absence of PNA-binding; these properties bear more resemblance to more mature T-inducer/helper cells. When combined with consideration of the morphological aspects we suggest that in both cases the abnormal cells represented precursor T-lymphocytes.