DIFFERENCES IN CLINICAL BEHAVIOR AND IMMUNOPHENOTYPE BETWEEN PRIMARY CUTANEOUS AND PRIMARY NODAL ANAPLASTIC LARGE-CELL LYMPHOMA OF T-CELL OR NULL-CELL PHENOTYPE

The histological, immunophenotypic and clinical features of 19 primary cutaneous anaplastic large cell lymphomas (cutaneous ALCL) were compa red with those of 18 primary nodal anaplastic large cell lymphomas (no dal ALCL) of T-cell or null cell type. Although cutaneous ALCL and nod al ALCL had identical morphological features, differences in surface m arker expression and clinical behaviour were found. Immunophenotypical differences concerned the expression of epithelial membrane antigen ( 82% of the nodal ALCL were positive v. none of the cutaneous ALCL) and the cutaneous lymphocyte antigen (HECA-4 5 2), a possible skin-homing receptor on cutaneous T-lymphocytes (most tumour cells in 44% of cuta neous ALCL cases were positive, whereas nodal ALCL showed expression o f HECA-4 52 on only few tumour cells (< 2 5%) in 18% of cases tested). Loss of T-cell markers was more pronounced for nodal ALCL. Patients w ith cutaneous ALCL were generally older (median 61 years) than patient s with nodal ALCL (median 24 years) and, in contrast to the latter gro up, did not show bimodal age distribution. Survival after 4 years, usi ng lymphoma-related death as an end-point, differed significantly betw een cutaneous ALCL and nodal ALCL; 92% for cutaneous ALCL and 65% for nodal ALCL (P=0.04). The better survival of cutaneous ALCL patients co uld not be ascribed to differences in age, stage or initial mode of tr eatment. These data indicate that differences in immunophenotype and c linical behaviour exist between morphologically identical primary cuta neous and primary node-based ALCL. They indicate that the primary site is an important prognostic factor in predicting the clinical outcome of ALCL.